Wednesday, December 10, 2014

Digital Insulation Tester

This is a photograph of a 20 Tera Ohm Insulation Tester I made around 20 Years Back. It had even Polarization Index for Transformer Insulation.

Digital Insulation Tester

The Product above is made with two circuits below.
A regulated, low ripple, high voltage of very low current capability is applied by instrument on a DUT (device under test). The leakage current in nA or pA (picoamps, nanoamps) is measured and readout, The Innovation i did was to measure the current in Vref and not Vin of ICL7107, this made the 1/x computation.

Insulation Tester or Tera Ohm Meter with Polarization Index

Also using the ICL7650 Chopper Stabilized amplifier must be done as shown in data sheets with grounded guard rings. pA will leak on the PCB itself if layout is not done keeping this in mind.

Sunday, December 07, 2014

DMM or Digital Multi Meter

Digital Multi Meter - New Year Resolutions
  1. I will not drop the DMM from a height of 4 feet.
  2. I will not Test Live Powered equipment in the Ohms Mode.
  3. I shall not Measure Mains Voltage in The Current Mode.
  4. I shall get it calibrated once a year or at least once a decade.
  5. I shall not use it in High Energy Measurements.
  6. I will try my best not to give it to my best friend.
  7. I can remember Red is Positive and Black is negative.
  8. I will wear shoes and stand on a block of wood while i test.
  9. I shall not operate the rotary range switch at high speeds.
  10. I shall replace the probes-cables-connectors on wear-tear.
  11. I shall not accidentally keep the hot-iron near the DMM or leads.
  12. I shall not keep DMM on tall table and pull it with the leads.
DMM - How it Looks ... shown is from Fluke Electronics

DMM or Digital Multi Meter

How To Learn Electronics :

Theory must be studied once and referred to, again and again as you do practicals. One is by building DIY projects and then modifying them. Also Repair of equipment, troubleshooting, testing and calibrating. Then you know how components behave and real life limitations. Now design and engineer a product and test it at customer site. do a pilot production and test with more clients. Now you will learn to think based on practical applications.

"with hard work and innovation you can do it ! "  Solderman Talks 1702 AD

- Solderman Talks 1702 AD

Tutorials on Basics and Instrumentation Electronics


More About DMM

Thursday, December 04, 2014

Transformers Series and Parallel Connections.

Series and Parallel Transformers

Series and Parallel Connections in transformers. Observe the Dot-Polarity. When windings are in parallel the current capacity doubles. When windings are in series the voltage doubles. Wrong dot polarity in series connection just cancels the voltage and a small residual imbalance voltage remains. If wrong polarity connection is done in parallel, then a short circuit or overload may occur.

Basic Electrical Circuits

Series and Parallel Transformers
Center Tap Transformer

This is when you need to build a symmetrical dual supply like +12V and -12V supply for an opamp design.
This is also good for a two diode full wave rectifier. But when you make a dual supply use a bridge and the center tap is ground. If you use just two diodes then one winding may be loaded more than other. That may not be good for long term transformer life. The core may get magnetized.

Center Tap Transformer

Thursday, November 13, 2014

Types of Switches in Electronics

Switches are electromechanical devices. The are used to control the path of current or energy flow. Power switches are used to turn on and off loads. The contacts should be robust and have immunity to sparking and corrosion. Switches for signals need to be gold plated for low contact resistance and within a sealed enclosure.

Types of Switches in Electronics

A Neon bulb should have a resistor is series to make a Neon Lamp. All specs in designer viewpoint.

Switch contacts and fuse contacts can spark badly and cause fire hazards, periodic examination, service and replacement may be necessary. The sparking also causes spikes, emi, along with inductors or coils or even long wires that are wound up in the path of current. This effect damages smps and electronic systems in its path, if not adequately protected.

The low signal switches do not have the above problem. Then.. switches that need to control microamps of current and battery contacts of portable electronics that consume micro power have a unique problem. A thin oxide layer on the contacts or thermometric emfs due to electroplating defects can cause bizarre effects. These contacts must be immune form the environment, sealed, gold plated and clean. Even a little ammonia gets close to the contacts could cause problems in signal and power switches.

Water, sunlight, corrosive fluids and exposed or heating electromechanical contacts  in connectors and switches are a designer and service engineering challenge.

Thursday, November 06, 2014

Aaron Cake Electronics

Aaron Cake  has many electronic circuits and other electronics information in his archive that is online since the 90s. Antique electronics and Parallel Port Programming.

Aaron Cake Electronics

Aaron Cake Electronics

The Schematic Symbol Reference, How To Solder and Desolder helped many electronic beginners in building their Projects. This was a valuable resource in those days even though it appears common today. The internet was used to genuinely share useful learning and ideas.

Tuesday, November 04, 2014

Circuit Land - Tony Van Roon

Tony van Roon VA3AVR has built Circuit Land. This site is as old as the html web internet, means 1995. Earlier it was a part of a Canadian University Site, when i discovered it in late niceties..

Schematics, Hobby Projects, Tesla, Marconi, 555, Metal Detecting, Electronics-Tutorials and a lot more..

Circuit Land - Tony Van Roon

Circuit Land - Tony Van Roon

Highlights -
  • Morse Code Practice Keyer,
  • Constant Current Charger
  • Touch Activated Alarm System
  • Miniature FM Transmitter
  • Continuity Tester, Smart
Tutorials on Photosensitive Devices, Transistor Tutorial, 12 parts, Opamp and Digital Tutors. Compeonet Testing Methods. Basics of Batter Charging, LEDs and Relays too.

Thursday, October 23, 2014

Design of a ADC Interface

(Summary) This is in continuation of the thread called "Design of a Thermocouple Amplifier" doc00023.html which is in the same section .

This is just a formatted-edited email thread exported from Eudora from my mailbox using the content concentrator. The circuits below were made by TF a student, This thread has been put online to share information.

The part under "From: delabs" are my writing. there may be some mistakes and broken links.

Datasheets -  AD590 from Analog Devices - - MCP3002 from microchip.com

Circuits Drawn by the Student.

1. ADC Circuit.



2. Power Supply Circuit.

 Power Supply Circuit.
From: TF

Now I will start working on the CTC and the ADC part.

From: delabs

Now it looks ok, use bases for all ICs, which ADC you are using ? Try to look at LTC1298 a 12 bit 2 channel, look at link below....

8051SBC V1.0 - Microprocessor learning board demonstrates exemplary design of 8-bit singleboard computer. More peripheral and easy to adapt to be a dedicated controller.

Read the Full page - Design of a ADC Interface for Microcontroller. - Fulll

Sunday, October 19, 2014

Design of a Thermocouple Amplifier.

(summary) This is just a formatted-edited email thread exported from Eudora from my mailbox using the content concentrator. The circuit above was made by TF a student, This thread for circuit above has been put online to share information. The part under "From: delabs" are my writing. there may be some mistakes and broken links.


1) Reg diagram STC1000A :
Is the reference voltage REF used for cold temperature compensation ?
2) What is the function of q1 and q2 transistors ? Are they also BEL100N ?
3) What is the function of VR2 ?
4) What is the function of P2 , P1 ?
5) How can I calculate the voltage at the output IC2A?
6) Is is possible for you to send me a circuit explanantion which will help me to understand all the circuit operations ?

Design of a Thermocouple Amplifier.
The circuit stc1000a.pdf is here name is "temperature controller, j and k input, pdf"

From: TF

REF is pin no 13 in header of the connector CON1 of board STC1000A. The CON1 of STC1000A is plugged into CON1 of STC1000B main board. it goes to Stable Reference LM336 2.5 IC2 of STC1000B, the entire STC1000x series is a set. RT1 is for cold junction compensation, see how to build it in dact0006.pdf .

Q1 and Q2 are BC547 small signal NPN, The act like crude attenuators with the resistor networks. This circuit is to linearize the output, study other circuits in my page you will understand. When the analog voltage becomes a bit more than 1% off from a line the switch can be put on. You can even use things like CD4066 and other analog switches but it will increment the cost. IC2D is just a differential opamp circuit see theory.

This amp switches the transistors to linearize output at an area determined by VR2. P1 and P2 are for 'zero' cold junction and 'full scale' calibration, these are given in the theory section. IC2A is a buffer there is nothing to calculate, read the theory here you have to study many of the links i post and also many other links to other sites, that will help you more.

delabs

Read the Full Page - Design of a Thermocouple Amplifier Full

Sunday, October 05, 2014

Testing Points and Pilot Production

Some Pilot Production And testing points when building electronic Projects.  These are also important while prototyping and Bread-boarding. These are things that i used to keep telling youngsters when they are new in manufacturing. This was when i was running my own firm making industrial equipment and instruments.

I used to even give this and some other pages around in printed format, it was composed with word on windows 3.11. Then i realized it has to instructed at every incident by example. Reading does not help unless someone is passionate and enthusiastic about learning.

Tutorials on Basics and Instrumentation

Testing Points and Pilot Production

Components
  • Use 1% MFR 100 ppm resistors for all analog instrumentation.
  • Use plastic or-and multilayer capacitors as ceramics are leaky.
  • Product should have minimum number of fasteners.
Assembly
  1. Nuts, Bolts and screws locked with adhesive so that they do not slip and the product falls apart.
  2. Potentiometers should move smoothly and not get twisted, strained or locked due to cabinets.
  3. Use Strain relief for wires and strip the wire and solder properly where required.
  4. Strip with a stripper do not use your teeth., Twist all the strands Tin the tip of the wire.
  5. After Tweaking and setting presets or trimpot lock it with paint or varnish.
  6. Big Components should have large pads and separate mechanical fixing to PCB.
  7. Acrylic and plastic can get blurred or deformed with some solvents.
Testing
Do assembly of the card with a tested assembled 3D reference. Even after all the care if the card does not work, then after full assembly do visual inspection in this order First keep both the cards one reference and the other manufactured under a bright light.
  • Compare resistor color patterns one by one.
  • Compare Electrolytic capacitors physical appearance and POLARITY.
  • Verify values of plastic and ceramic capacitors.
  • Cross-check Diode sizes and POLARITY. Verify Zener values.
  • Check IC and Regulator POLARITY and Exact type number / brand
  • Check Transistor, MOSFET, LED, POLARITY. and verify display type No. and Polarity .
  • Check for connector patterns and polarity and switches etc.
  • Reverse the card and Check for solder bridges between close pins .
  • Reverse card and Check for hairline shorts and solder streaks due to bad PCB processing or Soldering.
  • Reverse card and check for hairline cuts or pads lifted off card.
  • Closely observe for dry solders on big electrical parts (L and TX) a dry solder will cover the pin and will be dull in shine.
  • before calibration allow for product to warm up for 15 mts.
If all the components were subject to incoming inspection and testing. If still unit does not work remove power and do cold check comparison with reference unit in DMM 200K R range, if still problem persists continue with power on testing and solve by DMM or scope tests.

Danger ! when DMM is in Ohms Mode, Even if one probe touches 230 V, DMM is Gone, so take extra care while doing this. test probe.

delabs Technologies

First written and printed offline in the Nineties. Word on Windows 3,11 with Epson 24 Pin Dot Matrix Printer., updated 2014.

Electronic Tables and Charts

How to Test Verify the Testing Methods Itself

Testing and Evaluation tools must have dynamic decoys added into the device under test DUT or the batch under test. In a Conveyor system, identifiable (RFID) decoys must be artificially introduced every 100 pieces. This will constantly counter check the Testing system and in not a One time operation. The decoys should be defective or have a fault, a little above threshold. This is caught by the testing system. Even when the testing system ages or goes out of calibration, this method can raise a alarm.

Even in software and text/data processing; this method ensures database quality and software program integrity.

Wednesday, September 10, 2014

Electronics Work Culture and Discipline

Systematic and Meticulous work has its own Rewards. An Engineers Notebook or a Hobby Experiments Log Book can go a long way in making a Cauliflower out of every Cabbage. (The credits of the Vegetable Analogy goes to Mark Twain)

1. Keep Work Place Clean.

Clean Tables and shelves every day before closing office, Put Cut leads and Solder shots in a separate cup to be accumulated and disposed later as these are toxic. In this cup other irritants like staple pins can be added and these can be clubbed in a month and disposed off as one metallic bulk for recycling. Never bring coffee or food to work area, Keep a waste paper basket on your side.

2. Work carefully to avoid injury

When cutting leads hold the lead in the hand and cut or it will fly all over the place. A piece like that may land on another equipment and cause shorts or it may go right into your eyes and cause blindness. Lead and Iso propyl alcohol and other Chemicals may be dangerous for health if handled carelessly. Do not use fingers, and teeth as tools it is bound to cause a injury to repent a lifetime. Be extra careful with 230V AC and more so with 440V 1 tr 2mA thru your heart and a weak streak of luck may be the last experience you ever had. Do not press your Luck too hard.

Electronics Work Culture and Discipline

3. Protect Desk or table surface.

If you are cutting something let it not leave marks on table, even adhesive stains should not deface table, use a asbestos, Bakelite, fiberglass, hardboard surface which can be disposed once in a way. Before working put two layers of news paper on the table this prevents table from getting spoilt while soldering and newspapers being hygroscopic (water absorbent) they provide a natural antistatic surface to protect CMOS Ics and are nonconductors for any Live PCB kept on the paper.

4. Use tools and equipment's in a gentle manner.

When you use weller Iron use it as a heat transfer tool never use it for prying or crimping leads or just pressing use pliers or other tools for that.

5. Document what you do and vice versa.

Have a register in which you can make records of what you did to solve a problem or what you learnt while making an equipment this information is valuable for the company to develop production methods and also useful to your team to solve a similar problem. Share abilities and skills with fellow employees but don't share your company's technology and database with any other company. When you leave a company use only the abilities and skills in that broad area to evolve as a professional.

delabs notes - 80s and 90s

Tuesday, September 09, 2014

Fluid or Water Level Indicator with Reed Relays

This is a way by which you can monitor the level of fluids like water in a tank. Based on data from the sensor you can control things like solenoids or motors as required or even turn on a buzzer, hooter or annunciator in a control panel.

Fluid or Water Level Indicator with Reed Relays
Description.

Look at the picture on the right, the float can be a Styrofoam type with a couple of ceramic magnets stuck inside. The float must move freely up and down a long plastic pipe of around 10 mm dia. If the fluid is not water but a solvent then design a non-soluble float or coat the float you made with something like an epoxy resin.
Then you need to assemble a small circuit within the long plastic pipe. Many reed relays with a chain of resistors in series has to be inserted in the pipe. The resistor and the glass reed relays should be in different levels of the pipe where you need an alarm or indication. Seal the pipe hermetically at both ends with epoxy resin after taking out a shielded cable of just 2 wires + 1 ground shield.
When the fluid level changes, the float moves up or down with it, when the float moves over a section of pipe where the reed relay is mounted, the magnets on the float make the reed operate and the resistance of the sensor changes.

The resistance is measured and the alarm can be operated as you like. The advantage of this arrangement is the electric circuit does not come in contact with the fluid, no sparking risk.

Reed Relay. It was invented by Dr. W. B. Ellwood at Bell Labs in 1936. Contacts are in a sealed glass tube filled with inert gas like in a bulb, so they do not corrode. It is faster than regular relays and as no spring is used it has a longer mechanicalreed relay life. The two contacts are ferromagnetic blades plated with rhodium. When you take a magnet close by, the contacts touch each other. You can also put the reed in a coil, then when you energize the coil the reed operates. Used in telecommunication.OKI is one manufacturer of this type of component.

Design and Caution.

When you drive inductive loads you have to use RC snubbers, freewheeling diodes, varistors or zeners. when you drive lamps the cold current is high so use thermistors. The Reed relay is best used in telecom and instrumentation and avoided in power electronics. It can handle high RF frequency as the path of current is straight and footprint small.

Here is a Circuit to Build and Learn this Concepts -

Fluid or Water Level with Reed Relays

"When you use the DMM or digital multimeter, try not to use it for high voltages and currents, use Solderman Talks 1702external shunts and attenuators instead. If you try to measure 230V AC in the Ohms mode or in the Current mode with the probe in the current socket then you will see fumes in your DMM and a hole in your pocket !!" 

- Solderman Talks 1702

Saturday, September 06, 2014

Thermocouples and RTD Tables

The easiest way to measure temperature is with a glass diode like 1N4148 or a metal Transistor like 2N2222. These have a small temperature range, probably -5 to +120 is possible, but non-linear. A copper coil or any metal wire or even a wirewound resistor can work as temperature sensor but the thermal inertia makes it sluggish. IC semiconductor based sensors like LM335 and AD590 are easy to work with and pretty accurate. In industrial environment many types of Thermocouples, Pt-100 RTD and Optical Infra-Red Temperature measurements are used.

Input Levels for Thermocouples and RTD Pt-100. And the ways it has to be used. Thermocouples are selected on the basis on how they are mounted or fixed, the environment, the temperature range that is measured and finally the price you can afford for a particular application. Sometimes mechanical wear or chemical environments may eat away the sensors, so a cost-effective solution has to be evolved.

One customer wanted a special Pt-PtRh very high temperature sensor for molten aluminum. It was very difficult and costly to even arrive at a solution. So a non-contact infra-red sensor may save lot of time-money and even reduce risk of injury.

Thermocouples and RTD Tables

For J, K, and T Thermocouple Read "Temperature" + Room Temperature for mV shown applied to equipment, eg....

If Room Temperature is 25 Deg C and mv applied is 10.777 for J Type STC1000 then reading should be 200 + RT = 225 deg C. The mV shown are for Reference Junction at 0 Deg C.

It would be better if you refer links below, The above table i made long ago, then a Scan with OCR later formatting. It could have errors.

Read More

Monday, August 18, 2014

Binary and Hex Numbers

Computers understand numbers and logic, as most are digital computers. The Binary Hexadecimal System is the way the numbers or logical commands are instructed to the computer. All input devices or sensors must finally talk this language to the CPU, and all outputs and actuators must be able to understand this numbers to do their job.

Binary and Hex Numbers

A bimetallic thermostat is like a simple mechanical computer. Where the bimetal response is the sensor input, the contacts are the output to actuator and the bimetal thermal behavior is of the nature of intelligence. Similarly we have opamps which can be real-time complex analog computers. And the Living Being are like biologicals robot which have all the things - a control systems, computers, sensors and actuators, even probably a wireless network. :-)

Binary Numbers
  • Bit is 0 or 1 ... one digit ... 0 could be 0 volts and 1 five volts.
  • Nibble is four bits, 4 digits, like 0010 , in hex a nibble is 0 to F.
  • Byte is eight bits, 8 digits, like 1100 0010 , in hex 00 to FF.
  • BCD binary coded decimal is binary code for numbers 0 to 9.
  • Learn more by reading asciicat here. Download and use.
Computer Science and of computer programming, while emphasizing the development and analysis of common data structures and algorithms.

CS152, Fundamentals of Computer Science II, and Programming Languages.

A Tutorial on Binary Numbers

Samuel A. Rebelsky
  • Basic Concepts Behind the Binary System
  • Binary Addition
  • Binary Multiplication
  • Binary Division
  • Conversion from Decimal to Binary
  • Negation in the Binary System
A Tutorial on Binary Numbers

Sunday, August 17, 2014

Resistor Color Code

The Resistors Value has to be Deciphered by understanding the well kept Secret Color Code that is known only to Makers, Ham Radio, and Engineers.

The Resistor have colored painted bands, makes electronic populated PCBs look attractive, but that was not the real purpose. It was an early innovation in what is called now Ergonomics of the Workplace. In other words it makes you spot values easily and also their magnitude.

If you find a black resistor on the PCB with no color stripes, it means it has burnt up and would have values less than 10K. You have to research the design to arrive at the value of that blown device.

1st band - 1st digit - Yellow = 4

2nd band - 2nd digit - Violet = 7

3rd band - Red = 2 -- number of zeros that follow -- means 4700 ohms -- 4.7 kilo ohms or 4k7

Resistor Color Code

For 4 banded ones, MFR 1% first 3 bands represent first three digits, and fourth band stands for the number of zeros that follow. 4.7k will be Yw Vt Bk Bn.

Right End Band is for tolerance

Brown Band 1% -- MFR Metal Film Resistor is used in Instrumentation Electronics.

Gold Band 5% -- CFR Carbon Film Resistor is common for Consumer Electronics.

Silver Stripe is 10%

Read more at my Basic Electrical Circuits

Thursday, August 14, 2014

Exponents - Giga Tera Pico Nano

In the Metric System you will encounter prefixes for numbers. In electronics, right from resistors to hard disks these units are used. So you have to have in your memory, at least the ones below, so that you place the correct value of cap or inductor in your circuit.

See SI Units or Metric Units to read more about these. R, C and L values are given these prefixes.

We have resistors like 10 Tera Ohms of Glass Surface Resistance to 1 Micro Ohms of a Small Copper Wire Resistance.

1 Pico Farad of Capacitance of two Large PCB Tracks in a Multi Layer PCB to 10 Milli Farad of a Huge Electrolytic Power Supply Filter.

Then Lastly 10 Nano Henrys Inductance of the Twisted Connector Cables in a Computer and 1 Henry of a Powerful Choke that can kickback 10 Kilo Volts when a 10 Amps current thru it is broken.

Exponents
Tera 1000,000,000,000 1.e+12
Giga 1000,000,000 1.e+9
Mega 1000,000 1.e+6
Kilo 1000 1.e+3
units 1 1.e+0
milli 1 / 1000 1.e-3
micro 1 / 1000,000 1.e-6
nano 1 / 1000,000,000 1.e-9
pico 1 / 1000,000,000,000 1.e-12

Electronic Tables and Charts

Electronics is Fun, is it Not.

 Just Google 0.1% or 1000/1e6 or 1000/1000000 ....answer in the calculator that pops up is same. Read "Parts Per Million - PPM" as used in Resistors. 1000 ppm is 0.1%.

Most MFR Resistors have a Temperature Coefficient of 100 ppm/°C.  Read more at ­ Resistance - Ask The Applications Engineer. 100ppm is like 0.01%.

0.01% is close to the resolution of a 4-1/2 Digit Voltmeter. 100.00 is the reading you will see for 100 Volts. Imagine the front end attenuator in that voltmeter is Standard MFR and a "Hot" Voltage Regulator is leaning on it, (you wanted to make your pcb compact)  The last digit will be Spinning like a Ferris Wheel. Are we understanding Instrumentation!

Read - Accuracy, precision & resolution

Parts Per Million - PPM

Wednesday, July 23, 2014

Product Development Fundamentals

A. Product Design Sections :
  1. Electronic Engineering - Circuit Design, PCB Design, EDA. 
  2. Mechanical Engineering - CAD, Tool and Die Design, Enclosure 
  3. Software Engineering Firmware - PC ware, CASE, emulators 
B. Methods of Product Design :
  1. Design Automation. - Design and Simulation with Computer. 
  2. Computer Aided Design - Design on Computer, Breadboard test. 
  3. Conventional Design. - Paper design with Breadboard test 
Circuit Design Service of delabs  - Product and Circuit design. Consulting tech service.

Product Development Fundamentals



C. Criteria of Product Design :
  1. Ergonomics - User friendly Interface of controls, display, etc..
  2. EMI / RFI Ext.- Immunity to external electrical disturbance.
  3. EMI / RFI Int. - Reduction of Internal electrical noise generation.
  4. Input Cost - Selecting Cost effective components and methods.
  5. Product Safety - Eliminating shock hazard, fire hazard or stress.
  6. Corrosion res.- Resistance to Chemical Fumes, brine, gases etc..
  7. Reliability - Long Life reliability engineering, MTBF, stability.
  8. Serviceability - Accessibility - Maintenance and repairs, Self test.
  9. Vibration - Enclosure / Components to be vibration resistant .
  10. Ease of Manufacture.- Manufacture ease and provision for test and Calibration..
  11. PC Interface - RS232, GPIB, etc. for PC Control and recording.
  12. Upgrade Ease - Options, Software change, Hardware upgrades.
  13. Quality - Design, Components, Production methods.
  14. Accuracy - Specifications of performance and its stability.
  15. Misuse-Abuse - Rugged design both electrically and mechanically.
D. Criteria of Circuit Design :
  1. Technologies - Time proven technology and Standard Parts. 
  2. Reliability - Component Selection and Design Methods. 
  3. Modular - Allow for incremental upgrades and Service. 
  4. Safety Margins - Overrating for Voltage, threshold, speed, etc.. 
  5. Testability  - Test Points, Isolating Jumpers, self test mode. 
  6. Isolation - High voltage isolation, User safety, grounding. 
  7. Thermal Limits - Dissipation Limit, Heatsinks, Shutdown, Size. 
  8. Protections - Fuses, Current Limit, Zeners, Varistors, Alarm. 
  9. Power economy - CMOS Designs, LCD Designs, SMPS, Portable. 
  10. Electrical Parts - Connector selection, Relays, Switches, PCB. 
  11. Precision - Accuracy, Resolution, Drift, Thermal stability.
EE Design Library - Electronic Product Design Resource.

Tuesday, July 15, 2014

Talking Electronics - Colin Mitchell

An e-magazine for newcomers and everyone who likes to be involved with electronics., aimed at teaching electronics from the beginning with courses, tests and interactive questions.

Talking Electronics - Colin Mitchell

The thrust of the course is for you to be able to design your own circuits and eventually move into the wonderful world of electronics as a career.

Talking Electronics - Colin Mitchell

"There are many different types of power supplies, including batteries, plug packs, switch-mode supplies and a basic transformer and bridge"

The Power Supply - Basic Electronics

"However the simplest power supply consist of a transformer, one or more diodes and a large filter capacitor (electrolytic)."

Thursday, July 10, 2014

Play-Hookey - Online Classroom

This Website is intended for those intrepid individuals who, for whatever reason, find themselves looking for a less than formal approach to useful education in a number of technical fields.

Play-Hookey - Online Classroom

Digital logic is at the core of all digital computers, and yet it is entirely based on three fundamental operations, designated AND, OR, and NOT. See how it's possible in these pages…..
These pages now include coverage of the major logic families as well as some practical experiments that you can perform with real components to see for yourself how they work.
  • DC Electronic Theory.
  • AC Electronic Theory.
  • Op Amps and Analog Circuits.
  • Take a look at optics.
  • What's inside these semiconductors?
Line Clock - Play-Hookey

Line Clock - Play-Hookey

"In many digital circuits, we need a regular and continuous train of pulses to control the timing of various circuits. In some cases, we want two separate pulse trains, one the inverse of the other. In other cases, we may want two square wave pulse trains in quadrature...."

(An Excellent Interactive Resource, Technically Accurate, Electronics Edutainment - delabs)

Tuesday, June 10, 2014

Electronic Product Production.

a. PCB Assembly.

First Inspect PCB for hairline shorts and cuts and also traces of unwanted copper in the edges and repair them. Also Check if all Drill holes & Slots are proper size and PCB is Fitting in its Place properly, This is because Drilling and Filing should not be done after assembly as it causes serious reliability problems.

Second populate all the resistors, Jumpers, Diodes and Ceramic Capacitors these are tough components. Then Insert all Transistors, LEDs, Displays, Electrolytic Capacitors and IC s (Bases), Here care should be taken not to overheat any component as it may damage them. Lastly Solder Connectors, Relays, Coils and Transformers which may require a high wattage Iron, and Mechanical Reinforcements.

Electronic Product Production - delabs Technologies

b. Precautions during Production.
  • Observe Polarity for Diodes, El-caps, Connectors, etc.
  • Make sure of Pin 1 for IC s, Regulators, Transistors and Mosfets before insertion.
  • Avoid bases for ICs in production as these fail on use.
  • Make use of Electrostatic protection for CMOS devices.
  • When Cutting Leads use protective Goggles and do it in a separate place as the cut leads fly all over the place.
  • Use Iso Propyl Alcohol (IPA) as de-greasing agent on PCB.
  • Water & Detergent wash is very good but only if coils, Transformers, Relays are hermetically sealed- Impregnated.
Use a Lacquer-Varnish or RTV rubber coat on both sides of PCB including on the components to prevent corrosion and also it helps maintain accuracy-precision.

Lead is a kind of poison, use gloves or wash hands with soap after work is over. Flux, IPA, Thinner Fumes can cause respiratory health problems. Work in a ventilated area use Exhaust Fans and Open Windows. Dispose of Metal, Plastic and Chemical waste separately and well packed as these can contaminate the environment and also cause Injury.

Published online around - Nov 1999

Thursday, June 05, 2014

Amps-n-Volts Notes Corrected Improved

I have corrected, enhanced. moderated my design notes from my earlier Amps-n-Volts News Letter. My knowledge is limited to my experience, observation, perception, learning and beliefs, but i have to express my views freely. These posts are mirrored at Soldermans Basics.

Amps-n-Volts eMag

Near 2001 i started sharing my learning and experience in Electronics Engineering on Blogs and Newsletters. One of the Successful eMag and electronic email magazine ran for five years. I lost interest later in the email mag, and this magazine just morphed into a dozen or more Tech Blogs that run today. From the feedback i got, it has helped engineers and enthusiasts worldwide in Electronic Product Design.

Amps-n-Volts Notes Corrected Improved
  • Before you open a PC remove power, telephone modem and LAN cables else finger and screwdriver in wrong place can zap chips.
  • The products that survive the infant mortality time of say first six months will last quite long.
  • NTSC is like 320 x 240 pixels, which is TV, which is lower than your computer's 800 x 600.
  • When a microwave oven is turned on, a big spike is caused in the power line due to heavy inrush current on start up, Even pumps and motors cause such short time surges. This causes tripping of electrical protection circuits.
  • When a tree branch falls on the high voltage overhead electrical lines, they spark violently and supply trips.
  • Big or tall trucks go in small roads they may snap all low level cable or telephone wires on their way.
  • Do you need to turn on many equipments-machines all at once? do it one after an other sequentially or use a timer for delays. This is because at peak power demand time, turning on all can cause your fuse to blow or worse.
  • A battery that can be charged is best charged in CC constant current and CV constant voltage modes, that means both current and voltage have to be limited. When a battery is deep discharged many times it will age fast, and an empty battery will take huge currents so limit current. overcharging a battery will killit. After a voltage level is reached it should only trickle charge in mA and a battery has to be cut off on overload or before deep discharge
  • The Lead acid battery breathes a lot, so keep them in a well ventilated open space but rain proof. Use sealed maintenance free battery when possible, these are safer.
  • Teflon tape can be used to make leak proof pneumatic or hydraulic connections if junctions are leaking.
  • The current thru a 3mm or 5mm LED (light emitting diode) should not exceed 20mA, 15mA is quite good.
  • In a circuit swap all PNP and NPN , reverse all diodes and el-caps, reverse the supplies and input polarities, most of the circuit may still work like they did before.
  • A sharp bend in a PCB track is a huge inductance (say 1nH ) when it comes to RF. it may radiate or reflect, it may even act like an antenna and pick up RF from the SMPS, Motor or Cellphones nearby.
  • Persistence of vison around 16 frames a second (60mS) hence very fast events not seen .
Some of these points may be repeated and some not relevant in the present technical engineering scenario. As issues may have been set right, years back.

Amps-n-Volts Archive

Instrumentation Notes

Design Notes

Production Notes

Monday, June 02, 2014

Radio Electronics Magazine

Recently i found a collection of those mags at Archive.org ......

Radio Electronics Magazine at The Internet Archive

Radio-Electronics was an American electronics magazine that was published under various titles from 1929 to 2003.You can Read them all here ...

Radio Electronics Magazine at Archive.org

Hugo Gernsback, sometimes called The Father of Science Fiction, started it as Radio-Craft in July 1929. The title was changed to Radio-Electronics in October 1948 and again to Electronics Now in July 1992. In January 2000 it was merged with Gernsback's Popular Electronics to become Poptronics.

Radio Electronics Magazine at SWTPC
Gernsback Publications ceased operations in December 2002 and the January 2003 issue was the last.

Over the years, Radio-Electronics featured audio, radio, television and computer technology. The most notable articles were the TV Typewriter (September 1973)[1] and the Mark-8 computer (July 1974). These two issues are considered milestones in the home computer revolution.

Radio Electronics Magazine at SWTPC

Radio-Electronics was aimed at electronics' professionals such as radio and TV repairmen. And they were men, the tag line on the cover was "For Men with Ideas in Electronics".

Friday, May 16, 2014

DIY Computing on Raspberry Pi

Raspberry Pi is a Miniature Computer that can Interface with a Display Device like TV and a keyboard.

Raspberry Pi - ARM with Linux Nano Computer

Raspberry Pi - ARM with Linux Nano Computer

Learning Programming with DIY Computing

We now also have a tiny ARM SoC mini computer called Raspberry PI which helps you know how a computer works. Browse the Internet on your TV or learn coding in many programming languages.

(These ARM based devices power many of the small portable electronics we see today.)

Model B is the higher-spec variant of the Raspberry Pi, with 512 MB of RAM, two USB ports and a 100mb Ethernet port. It’s our most popular model: you can use it to learn about computing; to power real-world projects

The Raspberry Pi is a low cost mini computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse. It is a capable little device that enables people of all ages to explore computing,

Learn on Gadget Hacks and Making Things

A Typical Hardware Hobby Enthusiast is a Hacker when he starts learning, it is sometimes given the name of reverse engineering in another context. The Hardware Hobby Freelance hacker is better off, he is doing it for Learning and Education. Students should be given new and challenging projects in well equipped labs, to augment their skills and make them productive in their jobs from day one.

Hobby Projects - Insulation tester, LED Circuits, Meters.

Hobby DIY Electronics and Making Things at delabs

We all learn by breaking up things, to see how it works, then Fix things around Home etc. Later Create and Innovate perhaps, thats the way to go. To Invent something someday.

Circuit Diagrams Archives Reference

Here are some people doing just that, inspire you to create useful things for your Home. We should never become over dependent on others for everything, this will erode our knowledge base, skills and freedom.

Silicon Chip - Electronics Hobby DIY Magazine, Projects to Build and Kits too.

Nuts and Volts - Aimed at the electronics hobbyist, with articles covering amateur radio, cellular. communications.

Monday, May 05, 2014

UPS Power Inverter and DC to AC

Learn about Power flow, Sags, Dips, Phase rotation, Harmonics, Flicker and more!

Power Quality Teaching Toy

Power Quality Teaching Toy

Standards

CBEMA - Computer Business Equipment Manufacturer's Association adopted curve IEEE Standard 446 (orange book) curve. Recommended Practice for Emergency and Standby power systems for Industrial and Commercial Application."
  • Wave form Sine wave THD (total harmonic distortion) maximum 5%.
  • 3 Phase system phase imbalance of voltage 3% - 6%.
  • Frequency stability 60  +/- 0.5Hz.
  • Output Voltage +6% Max. -13% Min. from Nominal Value.
  • Voltage can fall to 0V but should recover in 0.5 Cycles.
  • On turn on Voltage should reach steady state within two seconds.
  • Upto 200% over Nominal Voltage should be tolerated for 100uS. ( Transients, spikes and Inductive Kickbacks come in this)
  • Upto 30% over Nominal Voltage should be tolerated for 0.5S.
ANSI - American National Standards Institute

"Standard Voltage Ratings for Electrical power systems & Equipment"
  • Steady State Variations +/- 5% of Nominal Voltage. T
  • Three Phase Voltage Imbalance 5% Max..
  • Standard Frequency 60Hz.
Glossary
  • Frequency 60Hz Hz is Hertz.
  • One Cycle = 20mS (milliseconds) one full sine wave.
  • Max - Maximum
  • Min - Minimum
  • uS - micro seconds, S - seconds.
Cause of Transients
  1. Switching Loads Simultaneously (inductive loads).
  2. Power factor correction capacitors and devices.
  3. Lightning strikes (enhanced by earth faults).
  4. Line Inductance (inductive kickback, resonance).
  5. DC and AC Drives for Motors.
  6. Rectifiers with large filters and stray inductance.

CBEMA Guideline
The CBEMA guideline, created by the Computer Business Equipment Manufacturers Association is a realistic, at-the-equipment, maximum allowable voltage that equipment can withstand, without damage or upset.

Tuesday, April 29, 2014

Ohms Law - Amps Volts Watts Relation

The most important Electrical Law is the Ohms Law, a proper understanding of which can help you make many designs. Troubleshooting Home Appliances or understanding Household Wiring is easy if you master this.

Ohms Law

Volts is analogous to the pressure of a water in an Overhead Tank. The water head or height is like Voltage. The Pipe diameter and bends are like wire and its resistance, a water tap like a wirewound potentiometer. The rate of water flowing from the tap is like the flow of electric current in a wire.

Ohm's Law - Watlow Electric The one i used to use, This would be in the back of the handbook.

The water drops are similar to units of charge, the quantity of water filled in a bucket is like the amount of charge stored in a small capacitor. The Underground Sump can be compared to a Big capacitor. The evaporation of water is like leakage of charge thru the dielectric in a cap. If you use the running water to power a home made paddle wheel turbine; This is like simulating an electric motor or heater in a water circuit, the rotary power got, can be analogous to the heater's watts..

Ohms Law - Amps Volts Watts Relation

By Dmvstar (Own work) [CC-BY-SA-3.0], via Wikimedia Commons

Thursday, April 17, 2014

Genrad - General Radio - Instrumentation

History and accomplishments of the General Radio Company, one of America’s first equipment manufacturers for the radio and electronics industry.

General Radio Historical Society

Founded in Cambridge, Massachusetts in 1915, GR provided the tools and instruments that allowed the electronics industry to burgeon into today’s giant that fills our lives with radio, TV, computers, cell phones, DVDs and all the other electronic products in our homes, businesses and automobiles.

Type 608 Oscillator

Type 608 Oscillator - Genrad

The GR 608 was the world’s first R-C oscillator, announced in April of 1939. It was designed by H. H. Scott who worked for GR at that time. It used a separate twin-tee R-C network for each frequency which was selected by a push button.

General Radio Experimenter

This pioneer publication first appeared in June 1926 and became the model for many others to follow (most notably the HP Journal). It began with engineers talking to radio amateur customers and gradually changed to engineers talking to other engineers, who might also be customers.

GenRad 1863 Megohmmeter

GenRad 1863 Megohmmeter

The GenRad 1863 Megohmmeter is the choice for production and inspection tests on devices with resistances up to 20 Tohms. The GenRad 1863 will measure resistance at any of five test voltages of: 50V, 100V, 200V, 250V, and 500 VDC. Compared to the GenRad 1864, which has adjustable test voltages from 10V to 1090V, this unit has fewer controls, and is the more economical of the two models.

General Radio - GR

GR had an interesting philosophy of making instruments that were more modular than HP offerings. On the left is the popular HP 608 signal generator, which covered from 10 to 480 MHz in one unit. It had a zillion tubes, weighed a ton, and cost thousands.

Wednesday, April 16, 2014

Electrical Safety and Clean Energy Systems

This is an educative and important guide for Electrical Equipment Safety. This can be also applied partially to Power Electronics and Home Energy Systems. Electronic Equipment also have to be maintained by Calibrating them and protecting them from environmental parameters like dust, grime, direct sunlight, moisture, humidity, sea wind (brine), corrosive fumes and chemicals. They should not be even placed near machines like a big lathe, sub-sonic or low frequency vibrations.

Electrical Safety 1

Electrical Safety Testing Reference Guide

Electrical Safety is a Serious Issue Electrical Safety in the workplace is the most important job of an electrical worker. No matter how much training one has received or how much employers try to safeguard their workers, Electrical Safety is ultimately the responsibility of the electrical worker.

Electrical Safety 2

Electrical Safety Hazards Handbook

Power Studies, Arc-Flash Hazard Labeling, Data Gathering and Inspection, Engineering Services.

The steps to osha electrical safety

Electrical Design, Lighting and most important Earthing or Grounding. Good Reference Articles and Product Reviews.

Electrical Construction and Maintenancee Power Quality, National Electric Code, Construction, V/D/V, Ops, Equipment Rental Industry Resourc

Earthing or Grounding is something Audio Enthusiasts make a lot of fuss about. The Articles here about Balanced Power, Symmetrical Power Systems and Earthing throw light on ways to counter Audio Noise.

AC Power has the 50/60 Hz noise, now more AC noise can be picked up by poorly designed systems when so many gadgets around. These articles are also relevant for the instrumentation engineer. Dissonance is encountered when you build sensitive strain gauge based measurements or while measuring and transmitting micro-volts from a remote sensor to the dashboard/control panel.

Index of Technical Articles About Balanced Power

International leader in electromagnetic compatibility (EMC) and power quality (PQ). EMC Filters, RFI Suppression Chokes, Feedthrough Components.

Schaffner - electromagnetic compatibility

Schaffner - EMC/EMI components, harmonic filters & magnetic components.

Monday, March 17, 2014

Mitsubishi Electric Research Laboratories

MERL is the North American arm of the Corporate R&D of Mitsubishi. MERL conducts application-motivated basic research and advanced development in optimization, control and signal processing.

Mitsubishi Electric Research Laboratories

Mechatronics - Advanced control algorithms, system dynamics, modeling & performance analysis....

Digital Communications - High speed mobile communications, ubiquitous networking, reliable wireless...

Data Analytics - Predictive analytics (statistical machine learning, data analysis); decision analytics...

TR2003-35 Very Low-Cost Sensing and Communication Using Bidirectional LEDs

A novel microprocessor interface circuit is described which can alternately emit and detect light using only an LED, two digital I/O pins and a single current limiting resistor. This technique is first applied to create a smart illumination system that uses a single LED as both light source and sensor.

MERL - TR2003-35 Communication Using Bidirectional LED

Bidirectional communication with LEDs

These test boards use a simple protocol for data transfer which allows two unsynchronized devices to phase-lock to each other and exchange pulse-width- modulated data bidirectionally. A basic explanation of the protocol is that the two devices take turns flashing their LEDs at each other. A short flash indicates a 0 or SPACE state, and a long flash indicates a 1 or MARK state.

Saturday, March 15, 2014

Basics of Electronics

Basics of Electronics -

Electronics is the study of the antics of electrons, for that first a bit of static electricity which is the way non moving electrons behave.

Static Electricity -

Basics of Electronics
If you Rub a plastic comb or ruler on a dry cloth and hold it over very small bits of paper you will see the paper jump to the comb, this is electric charge an accumulation of electrons on the plastic comb which produced a field to attract the bits of paper.

Opposite charges attract each other, the comb now has negative charge pulls the bits of paper which is uncharged, and the comb loses its excess electrons to the bits of paper, the movement of electrons is current.

All Charged matter try to reach ground potential an uncharged state, which is the state of earth, earth is taken as zero potential.

Energy transforms from one form to another, when the comb was rubbed mechanical energy was changed to electric energy and the electric energy of the comb moved the paper, here electric energy changed back to mechanical energy.

When the comb was rubbed on the cloth friction caused vibration in the molecules of cloth, vibration causes heat which dislodges the electrons and these collect on the comb.

Same static electricity is the cause of lightning bolts and the crackling of your hair when you comb it on a dry day.
Insulators do not have free electrons but conductors have free electrons it is this reason the comb being an insulator could not stabilize its surface which had become charged, conductors like copper cannot get charged like this as electrons quickly distribute all over instead of accumulating on the surface. Conductors play an important role as they form the means to route the current formed by electrons to do work for us like lighting a bulb or running the Fan.
Electrons -
Like charges repel and unlike charges attract, This is because matter is assumed to be made of protons '+' , electrons '--' and neutrons '0' without charge. Protons could be absence of electrons or vice versa. What is important to remember is when stable matter is disturbed by friction, heat, light, other chemicals, even sound there is electrical activity which is interpreted in various ways even heat is an electrical activity a simple candle flame is also electrical activity, but we come out of that to study basic electronics which is the play of electrons in conductors, insulators and the most magical of them all the semiconductors.

The Ground that we walk on is made of mostly silicon dioxide or sand or quartz this silicon along with germanium and others are semiconductors, silicon forms most of the ICs in electronics. Selenium is another material but this is photoconductive, this is used in photocopying and printing. Gallium Arsenide is one other which is useful in high frequency components.

Most matters exhibit electrical properties piezoelectricity is one more, the long lasting gas lighter uses piezoelectricity (titanium derivative), these materials when hit generate electricity, this effect is used in record players (sapphire) to convert bumps on the record to electric voltages, batteries convert chemical energy to electric energy, and you know magnets produce electricity when moved over a conductor.

Conductors : Copper Cu , Aluminum Al, silver, gold, iron, tin, carbon, etc. .

Insulators : Wood, Glass, Ceramic, Mica, Sand, Paper, Cloth, Plastic. etc. .

Certain organic compounds are also conductors, and water with some electrolyte like salt is also a conductor but this is ionic or electrolytic conduction.

Wet wood or cloth with impurities can become very conductive and to some extent air itself becomes a bit conductive if humidity is very high. (RH relative humidity is high means the moisture content of air is high, very wet air).
DC and AC Current -
Current is the movement of electrons in a material, direct current is DC and alternating current is AC. If electrons move in a single direction it is DC.

Conventional Current flows from Positive point / terminal to a negative point / terminal.

{ the movement of electrons is opposite of this but don't bother about this was a bug fix done in those days :-) we all make mistakes }

A battery is the best example for a DC generator, The conventional current flows from higher potential + ve to lower -- ve, the water analogy of this is the + ve terminal is an overhead tank and the negative terminal is the ground tank the pipe carrying water is the conductor/wire and flow of water itself the current.

Positive + (red) and Negative -- (black) are called Polarities.
DC flows in a battery circuit as the battery by chemical reaction maintains one terminal with more electrons and the other with a shortage of electrons.

In AC the voltage or current alternates its direction periodically, in other words the polarities of the terminals change from + to -- and vice versa with respect to time.

Why AC ? this is a fundamental law of nature, from the macro movement of planets in the solar system to the micro movement of electrons in an atom there is a pattern called the sinusoidal waveform or sine graph or sine wave.

The movement of a pendulum is the best representation of a sine wave, when a magnet is rotated in a loop (coil) of wires or a coil is rotated in a magnetic field (near a magnet), the voltage that is generated is AC.

As rotation is the fundamental mechanical motion, it is also used to generate electricity which you use at home, AC power which is produced by moving magnets and coils of wire (generator) with the help of water power (hydroelectric waterfalls), steam, fossil fuel (petroleum,coal) driven machines, to nuclear plants.

"Sine graph is true even in the way civilizations have changed in history and to this day the life cycles of corporations, many believe when plotting a graph of profits or growth it is "up up and away" but the truth is that it is " up and down then round and round" !!"

- Solderman 1702

This is an old article i wrote, which may have errors or misconceptions, if you have any doubts verify with a Local Ham. If you want to study and learn the science yourself, then start here HyperPhysics.

Friday, March 07, 2014

Design of a Constant Current Source

This article will explain the way a simple transistor based current source is designed, this will give an idea on how some components can be used in a practical way to make the circuit do some function, the objective is not design but to become familiar with the basic ideas.

Tutorials on Basics and Instrumentation Electronics

Requirement.

We need a fixed current around 20mA for a voltage variation of 10V to 20V to drive a LED flasher circuit.
Component Selection. The transistor should handle 20V * 2 = 40V and a current of 20mA * 5 = 100mA. We have to overrate the components for long term reliability and make the design rugged. Chosen MPSA92 PNP-300V-500mA which is good for this job.

 Look at the pin details of MPSA92 in the bottom view given in the right of this page in its TO-92 package, it has a beta of 25 . The Power dissipation of MPSA92 can be upto 650mW , our requirement may be a max of 20V*20mA = 400mW which is just within limits.

Now we need a voltage reference a low cost voltage reference is a LED which has a 1.6V forward drop. As the circuit is a not an accurate one CFR 5% resistors are fine.

Circuit design.

The LED at 40mW will last long, some energy emits as heat and some as light. 40mW / 1.6V = 25mA. so let us choose 20mA max LED current as a thumb rule.

In this circuit the LED is used as a reference so to keep it cool a 2.2K is chosen. (20V - 1.6V) / 2.2K = 8.3mA on the high side and when voltage is 10V the current will be 3.8mA min. .

You should know that the LED forward drop can change with ambient light as it is photo sensitive and will vary with temperature.
Look at the circuit in the right, the LED has a forward drop of 1.6V which is applied across the resistor R4 and the base-emitter diode. That means 1V across R4 as a diode drop is around 0.6V. The base-emmiter now gets forward biased and a small base current Ib flows . The Ic or collector current is 1V / 50E = 20mA. The Ib = Ic / beta, That means 20mA / 25 = 0.8mA which flows thru R4 and R5.

The Load Resistor R6 represents the LED flasher circuit that consumes 20mA, even on short circuit of R6 the current is limited to 20mA.

When more current flows in R6 the voltage at emitter falls, the voltage at base is 20V - 1.6V =18.4V, and the voltage at emitter should be 18.4 + 0.6V = 19V for bias and Ibto flow. When Ic increases the Ib reduces to that extent as only to maintain emitter voltage at 19V, this way Ic is kept constant, if Ic reduces the voltage at emitter builds up to rise Ibwhich in turn builds up Ic. so we made a current regulator.

Circuit Improvement.

The circuit can be improved by using a zener in place of the LED or better still a temperature compensated reference like LM336.


The circuit on the right will be more stable, but still the forward drop on base-emmiter junction is temperature sensitive. The base current will also introduce an error, so you can get a 8 bit stability, that means around 255 counts on an A-D converter. If you need a more stable current source you should design with FET and opamps.
LM336-2.5 pdf details, It has a 2.5V drop. A LM336-5.0 pdf version is also available for 5V. these are from National Semiconductor.

Operating Current of LM336 is 400uA to 10mA, 20V The max. voltage 20V / 3.3K = 6mA. so within limits. Then you can compute the rest, wire it up to see if your design works.
"If all parts are working, connected in proper polarities and there are no dry solders and loose connections then any circuit well designed ought to work. "

- Solderman 1702



docc00009.html 21:46 01-Aug-04  delabs

Contents

Basic Electronics
Basics of Electronics
Product Production
Work Discipline
Testing Points
Learning Electronics
Electronics Theory

Production Notes
Prototype Fabrication
Electrical Circuits
Electromechanical


Library
Scots Guide Electronics
Engineering - Wikibooks
Design Lab - Jim Svoboda
DC Circuits UOG
Socratic Electronics
Blobz Guide Electric Circuits


Product Design
Product Development
Constant Current Source
Good Voltage Regulators
Insulation Resistance
Digital Insulation Tester
DN Schematic PCB 04
DN Product Design 07


Hobby Circuits
VU Meter Circuits
LED brightness control
555 Incredible Chip
Process Control
liquid level measurement
Thermocouples and RTD
Design ADC Interface uC
Thermocouple Amplifier
IA Instrumentation 02
Temperature on DMM
Optical Proximity Switch
Analog Mux - Data Acquisition


Test Measurement
Instrumentation Automation
NI Test and Measurement
DMM Digital Multi Meter
Oscilloscope in T&M
IA Automation 01
Build Instruments
Tektronix T&M Equipment
Educators Corner – Agilent


Power Electronics
UPS Background
Transformer Connections
DN Power Electronics 03
DN Power Electronics 02
Half Bridge Convertor SG3525


Embedded
Interfacing Microcontrollers
Embedded Process Control
80C31 8052 Microcontroller
Microprocessors and uC
Embedded Systems Design

Components
Good Voltage Regulators
Relays and Contactors
Potentiometers Trimpots
Prototype Boards Types
Types of Capacitors
Types of Switches
Resistors How they Work
Coils Transformers SMPS
Mains Transformers Types
DN Components Selection 05

Tutor Gadgets
Count-Up Timer
Digital Logic Gates
Electronics Tutors

History
Teaching Instruments
Charles Proteus Steinmetz
Muntzing a Circuit Design
Teralab Electronics projects
Historical Instruments


Tables, Charts, Videos
Binary and Hex
Resistor Color Code
Ohms Law
Giga, Tera, Pico, Nano
High Resistance Materials

Analog
School - Analog Design
DN Analog Basics 06
DN Op-Amps 01
TI Semiconductors