Testers or Instruments Electronic Circuits, beginning with T

Tester or Instrumentation Circuits, Page 13
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Last Updated on: Friday, March 12, 2010 12:07 PM

Circuits Designed by Dave Johnson, P.E. :

TEMPERATURE SENSOR WITH 4 TO 20mA CURRENT LOOP
I designed a circuit similar to this one years ago to accurately measure the air temperature inside a building 1000s of feet from a control room. The circuit uses the very robust current loop method. It uses a highly accurate semiconductor temperature sensor and an equally accurate voltage reference. The circuit includes a diode bridge, so it is polarity independent. By using the component values indicated, the circuit should not require calibration. It has a range from –40F to +120F and an accuracy of plus or minus one degree F.

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Talking Voltmeter - Ever needed to measure a voltage without taking your eye off something? If so, then this is the project for you! The Orton Talking Voltmeter takes a voltage measurement in the range 0-5 Volts and then reads it out to you to two decimal places (i.e. to 10mV resolution). The design illustrates the use of the 10 bit ADC in the PIC, .....(added 04/04/04)

Tamper-Resistant Watt-Hour Energy Meter - AN-563 Analog Devices Application Notes (app note added 6/06) Based on ADE7751 and Two Current Sensors

Tamper-Resistant Watt-Hour Energy Meter Based on the AD7751 - AN-574 Analog Devices Application Notes (app note added 6/06) With a Current Transformer and a Low Resistant Shunt

TC64X/TC64XB Evaluation Kit for Fan Speed Controllers - This is a complete evaluation board for evaluation and prototyping brushless DC fan control circuits using the TC642, TC646, TC647, TC648, and TC649 BDC fan controllers. (app note added 3/05)

TC74 Demo Board for Tiny Serial Digital Thermal Sensor - This allows the user to evaluate the functionality of the tiny TC74 thermal sensor and perform comparative evaluations against other thermal management solutions. Easy-to-use software provides a visual representation of temperature profile and can be interfaced with any PC. (app note added 3/05)

Technique Measures Small Capacitance - 09/01/97 EDN-Design Ideas: (design idea added 3/03)

Tektronix 535A oscilloscope schematic - (circuit added 07/07/07)

Telematics Box - (application / block diagram added 6/07)

Telephone Test Circuit with Audio Mixer - get Telephone audio to mixer or send audio to Telephone (added 5/02)

Temperature / Light Brightness Meter with LCD - Circuit measures the temperature and ambient brightness of the surrounding environment at the location it is placed. The data from the ADC is the calculated and displayed on the LCD. The main CPU unit on board the device is the PIC16F873. ….(electronic schematic added 11/08)

Temperature controller has take back half convergence algorithm - 09/15/05 EDN-Design Ideas: Enhanced closed-loop control balances stability, responsiveness.....(design idea added 9/08)

Temperature Monitor - (electronic schematic / circuit added 4/02)

Temperature monitor measures three thermal zones - 12/11/03 EDN-Design Ideas: You can use an ADT7461 single-channel temperature monitor; an ADG708 low-voltage, low-leakage CMOS 8-to-1 multiplexer; and three standard 2N3906 pnp transistors to measure the temperature of three separate remote thermal zones (Figure 1). Multiplexers have resistance, RON, associated with them;.....(design idea added 1/05)

Temperature Sensor with 4 to 20ma Current Loop - I designed a circuit similar to this one years ago to accurately measure the air temperature inside a building 1000s of feet from a control room. The circuit uses the very robust current loop method. It uses a highly accurate semiconductor temperature sensor and an equally accurate voltage reference. The circuit includes a diode bridge, so it is polarity independent. By using the component values indicated, the circuit should not require calibration. It has a range from –40F to +120F and an accuracy of plus or minus one degree F. ….(designed by David A. Johnson)

Temperature to period circuit provides linearization of thermistor response - 11/10/05 EDN-Design Ideas: Highly accurate pulsewidth varies with temperature.....(design idea added 9/08)

Test Batteries Without a Voltmeter - 03/15/01 EDN-Design Ideas:.....(design idea added 11/05)

Test timer - The output goes high for a fixed period of time when power to a unit under test (UUT) is turned on, and again when it is turned off. It was used with a magnetic sensor to test the spin-up and spin-down time of a gyroscope. Designed by Andrew R. Morris (added 6/06)

Test Video A/D Converters Under Dynamic Conditions - AN-297-Analog Device Application Notes (app note added 6/06)

Tester Checks Christmas Tree Lights - 12/23/99 EDN-Design Ideas:.....(design idea added 3/03)

Testing and Troubleshooting Digital RF Communications Receiver Designs - Aligent Application Note (app note added 04/05/06)

Testing CDMA Base Station Amplifiers - Aligent Application Note (app note added 6/07)

Testing inductors at application frequencies - Coilcraft RF Magnetics Application Notes -(added 6/06)

Testing Linearity of the LTC2400 24-Bit No Latency Delta SigmaTM A/D Converter Help from the Nineteenth Century - Design Solutions 11 Design Notes (Linear Technology) (app note added 2/06)

Testing of COP400 Family Devices - National Semiconductor Application Note (app note added 2/06)

The experimenter’s pot - Digital Potentiometer - ….(design added 08/08)

Thermal Techniques in Measurement and Control Circuitry - AN5 Linear Technology 6 applications utilizing thermally based circuits are detailed. Included are a 50MHz RMS to DC converter, and anemometer, a liquid flow meter and others. A general discussion of thermodynamic considerations involved in circuitry is also presented.

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