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Tester or Measurement (Instrument) Circuits

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Last Updated: November 29, 2017 05:38 AM

Circuits Designed by Dave Johnson, P.E. :
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  • UL Ground Resistance Tester -  UL requires that an electrical system using a metal chassis earth ground connection have a resistance of less than 0. 1 ohms. This resistance must be tested with actual line current in excess or 10 Amps. The circuit shown uses a couple of LEDs to indicate if in fact the resistance is less than 0. 1 ohms - modified on July 10, 2006 . . . [Circuit by Dave Johnson P.E.,  04/28/01]

  • Ultra Low Power detects Clear Fluid -  Using an ultra low power technique, this circuit detects when a clear fluid is inside a piece of clear plastic tubing. It can be used for fluid level control and monitoring . . . [Hobby Circuit designed by David Johnson P.E.,  10/22/05] 

  • Ultra Low Power Human Finger Detector -  The circuit below seems to work well and averages a current drain of only 10 microamps from a lithium cell. It uses a single CA4013 dual D flip/flop. One section is wired as a pulse generator. It applies 10us 10ma pulses to a LED inside a slotted optical sensor at a rate of about 50Hz. The phototransistor in the second half of the sensor detects the pulses and sends a pulse to the data input of the second flip/flop in the 4013 package. If there is nothing between the LED and the phototransistor, the inverting output of the 4013 remains low.  . . . [Circuit Solution by Dave Johnson P.E.,  05/02/06]

  • Under/Over Voltage Alarm on AC Line -  Power lines, which deviate much beyond normal voltages can damage expensive electronic equipment. The circuit below sounds an alarm whenever the line voltage is higher or lower than normal. I set the alarm limits at about +-15% from standard levels . . . [Circuit by Dave Johnson P.E.,  03/29/09]

  • Unplugged Power Cord Alarm -  Many medical devices, such a portable X-ray and ultrasound equipment, carry their own batteries. However, the frantic pace of some hospital emergency rooms might cause the device to be shoved off into a corner without being plugged back into an AC power source to recharge their batteries. So, I designed this circuit to emit an audible alarm whenever the device’s power cord was unplugged from the wall for a period of time . . . [Circuit by David Johnson P.E.,  07/08/00]

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Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:
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U.S. Navy TV-3/U Tube Tester manual -  . . . 

 

UJT Test -  This testing procedure is for use with a digital multimeter in the OHM's test-range. The UJT is a solid-state 3-terminal (TO-18 case) emiconductor. UJT's are used in pulse/timing, oscillator, sensing, and thyristor triggering circuits. The most common one being probably the 2N2646 from Motorola. . . .  [Tony van Roon's circuit]

 

UL Ground Resistance Tester -  UL requires that an electrical system using a metal chassis earth ground connection have a resistance of less than 0. 1 ohms. This resistance must be tested with actual line current in excess or 10 Amps. The circuit shown uses a couple of LEDs to indicate if in fact the resistance is less than 0. 1 ohms - modified on July 10, 2006 . . . [Circuit by Dave Johnson P.E.,  04/28/01]

 

Ultra High Sensitive Probe -  This circuit is so sensitive it will detect mains hum. Simply move it across any wall and it will detect where the mains cable is located. It has a gain of about 200 × 200 × 200 = 8, 000, 000 and will also detect. . .  [Izhar Fareed-Circuit Designer]

 

Ultra Low Power detects Clear Fluid -  Using an ultra low power technique, this circuit detects when a clear fluid is inside a piece of clear plastic tubing. It can be used for fluid level control and monitoring . . . [Hobby Circuit designed by David Johnson P.E.,  10/22/05]

 

Ultra Low Power Human Finger Detector -  The circuit below seems to work well and averages a current drain of only 10 microamps from a lithium cell. It uses a single CA4013 dual D flip/flop. One section is wired as a pulse generator. It applies 10us 10ma pulses to a LED inside a slotted optical sensor at a rate of about 50Hz. The phototransistor in the second half of the sensor detects the pulses and sends a pulse to the data input of the second flip/flop in the 4013 package. If there is nothing between the LED and the phototransistor, the inverting output of the 4013 remains low.  . . . [Circuit Solution by Dave Johnson P.E.,  05/02/06]

 

Ultra Low Power LCD Indicator -  This circuit serves as an ultra-low power replacement for multiple LED on-off indicators. It also has the advantage of being easy to read in full daylight. With the parts shown, it is possible to display four bits of information. . . .  [G. Forrest Cook]

 

Ultraprecise Current Sensing with LTC6102 -  Very low input offset allows using low value resistors while maintaining high measurement resolution. Using low value also reduces power losses and temperature rise. . . .  [Linear Technology App Note - , Jul 2, 2012]

 

Ultra-simple Voltage Probe -  . . .  [Designer's name not included]

 

Ultrasonic Range Meter -  On these pages, I will introduce the Ultrasonic Range Meter with PIC16F873.As for the range meter which doesn't use PIC, refer to "Ultrasonic Range Meter". I created the PCB pattern for this circuit using EAGLE CAD. With this circuit, the following features of PIC16F873 are used. . . .  [Seiichi Inoue's Web Site]

 

Under/Over Voltage Alarm on AC Line -  Power lines, which deviate much beyond normal voltages can damage expensive electronic equipment. The circuit below sounds an alarm whenever the line voltage is higher or lower than normal. I set the alarm limits at about +-15% from standard levels . . . [Circuit by Dave Johnson P.E.,  03/29/09]

 

Understanding and selecting RMS voltmeters -  05/11/00  EDN Technical Article: Failing to verify ac-voltmeter accuracy before conducting rms-noise measurements may cause highly misleading results. . .  [by Jim Williams and Todd Owen, Jim Williams, EDN's most revered contributor-At 63 years of age, Williams passed away in June 2011 after a stroke.]

 

Universal frequency counter & voltage meter -  . . .  [by Aleksander Stare]

 

Universal IR Remote Control Tester -  This tester consists of two integrated remote control receivers whose outputs drive an LED to indicate when a suitable infrared signal is received. To cover all current infrared remote controls, one receiver (the TSOP1736) has maximum sensitivity to carriers at 36 kHz, the other (the TSOP1738) to carriers at 38 kHzmust register on this site. . .  [Published in Elecktor July/Aug, 2010]

 

Unplugged Power Cord Alarm -  Many medical devices, such a portable X-ray and ultrasound equipment, carry their own batteries. However, the frantic pace of some hospital emergency rooms might cause the device to be shoved off into a corner without being plugged back into an AC power source to recharge their batteries. So, I designed this circuit to emit an audible alarm whenever the device’s power cord was unplugged from the wall for a period of time . . . [Circuit by David Johnson P.E.,  07/08/00]

 

Unusual clock with AT89C2051 -  . . .  [by IQ Technologies Industry, unless otherwise noted online]

 

Use a heated diode as a Flow sensor -  12/23/13  EDN Design Idea   A hot diode senses air or fluid flow. . .  [by Raju Baddi

 

Use a PC's parallel port to program a clock source -  12/07/04  EDN Design Idea   This Design Idea shows how you can use Linear Technology's LTC6903 programmable oscillator as a clock source for direct-digital synthesis, data conversion, switched-capacitor filtering, clock, and voltage-controlled oscillator circuit. . .  [by William Grill, Honeywell BRGA, Lenexa, KS]

 

Use a switching-regulator controller to generate fast pulses -  04/13/06  EDN Design Idea    Switching-regulator-controller ICs can deliver gate-drive pulses with rise and fall times of less than 2 nsec, making them ideal candidates for laboratory pulse-generators. . .  [by Mitchell Lee, Linear Technology Corp]

 

Use A Transistor and An Ammeter to Measure Inductance -  04/05/12  EDN Design Idea   Bipolar junction transistors transfer a current from a lower-resistance emitter to a higher-resistance collector. You can use this property to measure inductance. . .  [by Raju Baddi, Tata Institute of Fundamental Research, Pune, India]

 

Use Air-Core-Coil Resistance to Estimate Inductance -  01/05/12    EDN Design Idea   If the coil is tightly wound you do not need the number of turns to calculate inductance. This Design Idea shows how to calculate the inductance of a multilayer air-core coil using only its dimensions and resistance. If you know the dimensions and the number of turns on an air-core coil, you can easily calculate the inductance. With the dimensions in millimeters, the inductance, L, in microhenries is a function of the square of the turns, as the following equation shows: L=0. 008×D2×N2/(3D+9h+10g), where D is the average diameter of the coil; h is the height of the coil; and g is the depth of the coil—all in millimeters (Figure 1). . .  [by Peter Demchenko, Vilnius, Lithuania]

 

Use op-amp injection for Bode analysis -  09/16/04  EDN Design Idea   Bode analysis is an excellent way to measure small-signal stability and loop response in power-supply designs. Bode analysis monitors gain and phase of a control loop. It performs this monitoring by breaking the feedback loop and. . .  [by Martin Galinski, Micrel Semiconductor, San Jose, CA]

 

Use RS-232C port to measure pressure -  08/01/97  EDN Design Idea   A simple circuit and accompanying software turn a pressure sensor into an accurate and cheap pressure digitizer that works with any PC's RS-232C COM port. Many manufacturers make micromachined silicon piezoresistive pressure sensors. . .  [by W Stephen Woodward, University of North Carolina--Chapel Hill]

 

Use Your Personal Computer for Measurement and Control -  Scroll to find this circuit. . .  [Analog Devices-Analog Dialogue by Mills, John]

 

Use your printer port as a high-current ammeter -  07/06/00 EDN Design Idea   With a few inexpensive components and INT1Ch, you can turn the printer port of your PC into a high-current ammeter. . .  [by K Suresh, Indira Gandhi Centre for Atomic Research, Kalpakkam, India]

 

Using Histogram Techniques to Measure A/D Converter Noise  -  Analog Devices-Analog Dialogue. . .  [by Ruscak, Steve and Singer, Larry]

 

Using Vector Modulation Analysis in the Integration, troubleshooting & Design of Digital RF Communications Systems -  Application Note. . .  [Aligent]

 

UTP Cable Tester -  . . . 

 

V/I Curve Tracer -  The V/I Curve Tracer is an indispensable tool for troubleshooting circuits and testing components. The circuit traces the current versus voltage curve for the component under test on an ordinary oscilloscope. The peak-to-peak test voltage. . .  [Copyright © 1998 Wenzel Associates, Inc.]

 

Vacuum Tube Grid Leak Detector: Needs an Amplifier -  . . . 

 

Vacuum Tube Plate Detector: Needs an Amplifier -  . . . 

 

VCR head amplifier tester -  . . . 

 

VCR Tuner Based RF Spectrum Analyzer Schematic -  . . . 

 

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Test Equipment:  #'s - A        B - D        E - G
H - L        M - O        P - S        T - Z


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