Friday, March 28, 2008

Digital Count-Up Timer Gadget

Here is is Digital Timer Learning Gadget. The buttons make a sound and Light up internal LED lamps. Power On-Off control, Digital Timer; Start, Reset Scroll and Select are the controls. This will simulate the operation of a microcontroller based digital timer.

Project Page programmable-digital-timer



Press The Power on-off for a soft start, this is to prevent the inrush current from stressing the javascript components. Then it goes to a display test. The Start button can run or stop timer by toggling. The reset will Bring timer to 0000, format is min-sec.

Set by pressing select to get a marker over orange digit, Use Scroll to set number. Press Start to start timer, Start to be off to set again. The buzzer will turn on when Time elapsed matches time set. and the alarm relay trips. And a Flashing Annunciator signals end of process. Now Reset will start process again and stop flashing LED.
Digital Count-Up Timer Gadget

To use this like a regular instrument, you need a small portable hand-held computer with browser. Fix that in a Cabinet by filing or grinding it to size and wire the relays and supply. :-)

Wednesday, March 26, 2008

Learn Digital Logic Gates Operation

The Gate is a digital component that is used to compute an output for certain inputs, the inputs and outputs have two states high-1 and low- 0. Let us assume high is 5V and low is 0V (like in CMOS). On a high level the LED will light up and on a low level the LED is off. Now let us see what Logic means.

Screenshot of Widget

Learn Digital Logic Gates Operation

Digital Logic Gates
Gates are what make many of ICs, the two popular families are the 40xx CMOS and the 74xx TTL . Now 40xx come in 74HCT40xx flavors which approach the quality of an ideal gate. Entire circuits with Gates can also be also be burnt into PLDs, FPGAs and CPLDs just like you burn your CDROM. Gates can also be implemented in assembly language which a microcontroller like 8051 will understand and execute.

Hardware gate circuit will operate in real time, nano seconds delay will be there due to propagation delay, gate capacitance and FET switching times etc. Software or microcontroller gates code working will depend on both propagation delay and the CPU clock speed.

digital-tutors - project page.

Gates can be combined to make combinational or sequential logic circuits. combinational circuits are a complex network of gates interconnected to evaluate a pattern of output for patterns of input. Sequential circuits use memory elements hence output patterns depend both on input patterns and the memory of history of events. An example of combinational logic circuit is a seven segment display decoder CD4511 and and example for a sequential logic circuit is CD4029 up-down counter.

The CD40xx CMOS family can work at even 3V-9V-12V DC and consume low power. The speed is not as fast as 74xx TTL family. It is good for simple portable battery powered circuits. The 74HCTxx series is good for low power and high speed but will work at 5V. When you have problems interfacing CMOS and TTL use 74HCTxx family.

Tuesday, March 04, 2008

Megger or Insulation Tester

When a customer finds a Tera Ohm Meter expensive, Suggest a low cost scaled-down model to suit his need. These types are useful for people sub-contracting Telecom Equipment Manufacturing.

Even if we have Developed a High Precision System we cannot sell it in a Market that needs an Affordable Instrument with lower Specs. Three Types of the same Product for Three levels of Affordability and Field of Application. Get the idea?

Insulation Tester

Test and Measurement Instruments

This probably went upto 500V and 100V with a Toggle Switch and measured upto 1 Giga Ohm or 1000 Mega Ohms. The test voltage would be applied on the Switch, Connector or Magnetics to measure the leakage current in its insulation.

The leakage current would be converted to voltage, clamped with diodes and fed to the Vref of a 7107 which displayed the Insulation Resistance by doing a 1/x. Normally we use Vin to measure the voltage, in this instrument the Vin holds the Reference.

Monday, March 03, 2008

Heater for Heating Chambers

This was a Heater which was custom built for a CRT manufacturer, It is comprised of many Tubular finned heaters. And probably a big fan that worked at high temperatures. This was used in a Heating Chamber which aged or tested CRT monitors. It had a temperature controller, a remote indicator.

CRT Chamber Heater

Industrial Automation & Process Control

Multi Zone Temperature Controller

This is a Multi Zone Temperature Control panel used in Plastic Extrusion Moulding. We made many of these and it helped us learn cable management techniques. The panel is a standard way it was built and some of the merits were the selection of panel components and wiring expertise.

Multi Zone Temperature Controller

Hobby DIY Garage