Solderman Basic Electronics

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Wednesday, January 30, 2008

Sequential Timer - Pressure Switch

This was built in a 96 X 96 Cabinet. It takes the process thru three timer delays and the pressure is measured after a certain stage and at a setpoint the process, job or DUT passes or Fails. It could be stress, strain or load testing on object.

Sequential Timer

User Manual - Sequential Timer - Pressure Switch

Related Resources
Simple Sequential Circuit -State Machine - This lab will implement a stopwatch mainly based on a finite state machine (FSM). Other parts contain display, timer, counter, etc...

Synchronous switching of multiple electrical devices - An electronic timer consisting of CMOS integrated circuits is described that synchronously switches multiple electrical devices on and off..

Monday, January 21, 2008

Interfacing Microcontrollers

At Beyond Logic and Embedded Processor Control you will find interesting information on interfacing.

Real World variables are analog values, like the temperature of the Human Body. There may be Yes-No or digital events too, like the Water Level of a Tank or Door Close-Open. The former is measured by a Thermocouple and the Latter with a Proximity Switch.

These values from the sensors have to be Quickly converted to a digital form and fed to the the uC by an interrupt or cyclic polling of ports. The "How Quickly" determines How "Real Time" you system response is.

An analog value in instrumentation has to be at least 12 bit wide resolution, which is like 3-1/2, and the
The ICL7135 4-1/2 gives +/- 20,000 counts at full scale, nearly 14bit wide data. This can be interfaced both in serial and parallel data links. The serial method is used when optical isolation is required from the sensor to control circuits. If the sensor is measuring the temperature of a Transformer, an optical isolation is absolutely required.


delabs Technologies 06:48 20-Apr-07

Embedded Process Control

Microcontrollers are versatile for process control instrumentation, The Instruments need to be small and power efficient, they have to be immune to electrically noisy environments.

When such a instrument is mounted closed to big machines, it has to be resistant to vibration failure due to harmonics. When it is used in ships or chemical industries, they need to be corrosion resistant. This makes Industrial Instruments a challenge to design, as the reliability is next only to Medical and Military instrumentation.

In applications like data loggers, scanners and PID Controllers Microcontrollers are inevitable. The analog and digital counterparts that were built years back were difficult to maintain and very big in size. With a uC a 48*48 1/16 - DIN PID Box is possible, as shown here Newport Autotune PID.

Modular Automation like PLC uses many uCs. There are Multiplexers, Analog and digital modules controlled by uC. Modern Computer based SCADA have wireless interfaces and transmitters using uC based intelligent circuits.

delabs Technologies 06:48 20-Apr-07