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Tester or Measurement (Instrument) Circuits

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


Last Updated: October 24, 2017 02:55 PM
Circuits Designed by Dave Johnson, P.E. :

Time to Dust -  I have used the circuit below for many different applications, which require ultra low power drain.  it uses a single CA4013 flip/flop.  One section forms a pulse generator.  The generator produces 100uS pulses at a rate of about 1 per second . . . Hobby Circuit designed by Dave Johnson P.E.-May, 2006

Timer for Darkroom Camera Shutter -  This circuit was designed to control a film exposure shutter for a darkroom.  it has 8 time steps ranging from 0.35 seconds to 4 seconds.  it is activated by a foot switch and draws power from an external 12-volt DC supply . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Transistor-Switch Detects Audio Signal -  For some audio systems it is desirable to have an automatic switch circuit turn on other devices, such as an amplifier, if an audio signal is detected on one line.  The hobby circuit below will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.  The switch could be used to turn on a relay, routing the signal to where it is needed.  A single 3v lithium cell will power the electronic circuit for about 5 years . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747


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

Time to Dust -  I have used the circuit below for many different applications, which require ultra low power drain.  it uses a single CA4013 flip/flop.  One section forms a pulse generator.  The generator produces 100uS pulses at a rate of about 1 per second . . . Hobby Circuit designed by Dave Johnson P.E.-May, 2006

Timer for Darkroom Camera Shutter -  This circuit was designed to control a film exposure shutter for a darkroom.  it has 8 time steps ranging from 0.35 seconds to 4 seconds.  it is activated by a foot switch and draws power from an external 12-volt DC supply . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Timer warns when pills are due -  05/10/01 EDN Design Ideas:  Some people need to take medication at precise, regular intervals.  When you're in a hospital, a medical staff is present to ensure that you take your medication on time.    __ Circuit Design by J Terrade

Tiny Dew Sensor -  Dew (condensed moisture) adversely affects the normal performance of sensitive electronic devices.  A low-cost circuit described here can be used to switch off any gadget automatically in case of excessive humidity. At...__ Electronics Projects for You

Tiny EEG interface schematic -  Schematic Only__ 

Tiny pH Meter -  This tiny pH-meter is very tiny: 11cm2 including the PSU circuit!  I built it for the College Saint Pierre a few years ago.  it is based on a circuit developped at the Facultes Notre-Dame de la Paix, Namur, Belgium.  I modified several components to allow a smaller power supply__ 

Tiny Pulser -  The author repeatedly needed several different digital signals for testing his circuits, and a simple function generator did not provide a satisfactory solution.  He quickly developed a design for a pulse generator.  must register on this site __ Designed by Published in Elecktor July/Aug, 2010

Tiny twisted-paIR transmission line solves test-fixture woes -  112/06/05 EDN Design Ideas:  Commonly available wire fits in tight spots __ Circuit Design by Glen Chenier, Allen, TX

TinyScope-Simple Circuit all-valve 1-Inch CRT oscilloscope -  This oscilloscope uses a 1-inch diameter Mullard DH3-91 CRT.  Some nice pictures of the DH3-91 are here.  I found it at a car boot sale, priced £1.  i'm ashamed to say I didn't recognise what it was: I only bought it because it looked wierd and interesting!  ian did the main design and prototype work on the 'scope, then I rebuilt it with a PSU and front panel controls, and packaged it nicely.  Click here to read about ian's prototype.  The size of this oscilloscope is 164 x 83 x 83mm (6.5 x 3.25 x 3.25 inches). __ Designed by Hans Summers

TL431 Battery Voltage Monitor -  Monitor the voltage of a battery or battery bank using an TL431 (aka LM431) shunt regulator.   __ Designed by REUK-Renewable Energy UK website

TMP275 digital sensor thermometer -  I recently ordered some samples from TI , which included the TMP275 digital sensor.  The sensor has some nice features which I quote from it’s datasheet: The TMP275 __ Designed by Florin in DIY

Tomato Can Lightning Detector -  Schematic + info + pictures __ Designed by Lennie Zink

Trace voltage-current curves on your PC -  10/11/01 EDN Design Ideas:  Some years ago, one of the fundamental electronic instruments was the laboratory curve tracer.  A CRT display would sweep out terminal behavior (current versus voltage] from which you could derive mathematical models.  Classic present __ Circuit Design by Clayton Grantham, National Semiconductor, Tucson, AZ

Track multisite temperatures on your PC -  04/18/02  EDN Design Ideas:  The low-cost circuit in Figure 1 allows you to track four remote temperatures with thermistor sensors through the parallel port on your PC.  This four-zone thermometer instrument has a temperature range of –40 to +90°C and a resolution of better than ±1°C.  You can calibrate its accuracy to within 1°C over a 0 to 50°C span and within 3°C over a –40 to +90°C span.  Thermistors are low-cost, passive, rugged components, making them a good choice for temperature sensing.  The signal-conditioning hardware in Figure 1 performs a simple voltage division to partially linearize the thermistors.   __ Circuit Design by Clayton Grantham

Track Your Distance Through A Bicycle Odometer -  Just like cars that measures the distance it can travel, you can also do it with your bicycles.  We usually keep track of our mileage to see how far our strength can go but would it be of great use if we track it because we are maintaining a workout everyday considering the calories we__ 

Tracking Generator for a HP8569 Spectrum Analyzer -  Construction overview of a low-cost tracking generator for a HP8569-series spectrum analyzer.  __ Green Bay Professional Packet Radio

Traffic Controller -  This simple traffic controller can be used to teach children rudiments of traffic rules.  The circuit (shown in Fig.1) uses readily available components.  it mainly comprises rectifier diodes (1N4001) , a 5V...__ Electronics Projects for You

Tranistorized Dip Meter -  This dip meters use 2SC2369 transistor for RF Oscillator and 2SC458 for AM Tone Oscillator.  VR 10 K potentiometer is a linear type it adjust the working voltage of the RF oscillator part from 0~9 Volt DC,  -Contact hk @ ardiwinata.net

Transcutaneous Electrical Nerve Stimulator (TENS) -  A Transcutaneous Electrical Nerve Stimulation (TENS) device is, put bluntly, a machine for giving electric shocks.  The author was prescribed such a device on loan by his orthopaedic specialist.  The unit has a large number of programmes, of which he used only one.  Measuring the signals at the output of the device in this mode revealed damped oscillations at a frequency of approximately 2.5 kHz, with a repetition rate of approximately 100 Hz __ Designed by Klaus Rohwer - © Elektor Electronics Magazine

Transformerless Power Supply -  I have received a few emails asking for a transformerless power supply.  Here is such a supply.  This supply uses no heavy step down transformer and has an extremely low parts count.  The circuit can be built very small and can supply small currents for small projects.  The major downfall of this supply is that it is not isolated from the AC line and can only supply small currents __ Designed by Aaron Cake

Transformerless Power Supply -  Simple, low cost and easy to build power supply.  ideal for applications that doesn't require too much power. (5/28/2006)  __ Designed by Jose Pino

Transformerless Power Supply -  Power Supply Circuits:  This circuit will supply up to about 20mA at 12 volts.  it uses capacitive reactance instead of resistance - so it doesn't generate very much heat.  The circuit was designed to provide a cheap, compact power supply for CMOS logic circuits that require only a few milliamps.  The logic circuits were then used to control mains equipment, using an optically-isolated TRIAC. __ Designed by Ron J.

Transient load gives power systems a workout -  EDN Design Ideas:  02/02/2015    Verify power supply performance with this transient load generator __ Circuit Design by Mike Rose

Transient Test Correctly Models Nonlinear Part -  11/23/94 EDN Design Ideas:  Many versions of Spice include an ac analysis that calculates frequency response by linearizing the circuit model at its dc-bias point.  This analysis can be useful for linear, small-signal phenomena.  However, it loses validity for large signals' nonlinear analyses. __ Circuit Design by Ron Jesme, Alliant Techsystems, Hopkins, MN

Transistor & FVCs Make Linear Anemometer -  09/26/96 EDN Design Ideas:  The basic operation of this front-end sensor is identical to that of the earlier circuit.  Q1 is the self-heated airflow sensor; Q2 senses ambient temperature.  Zero-adjust resistor R2 sets the zero-airflow quiescen __ Circuit Design by W Stephen Woodward, University of North Carolina, Chapel Hill, NC

Transistor Forms RS-232C Digital Thermometer -  05/09/96 EDN Design Ideas:  An ordinary transistor can serve as an uncalibrated temperature sensor (Figure 1) for an accurate, PC-compatible thermometer.  Unadjusted accuracy is more than0.5°:C over the -50 to +50°C range, and the only limitation on resolution is the time devoted to measurement acquisition __ Circuit Design by WS Woodward, University of North Carolina—Chapel Hill

Transistor junction monitors remote temperature -  06/22/00 EDN Design Ideas:  The circuit in Figure 1 uses a regular, general-purpose transistor as the sensing element and a thermal-diode monitor IC to measure temperature.  The ADM1021 usually connects to an on-chip thermal diode on a CPU die itself, but in this application the sensor connects to a regulator low-cost discrete npn transistor, the 2N3904 __ Circuit Design by Matt Smith, Analog Devices, Limerick, Ireland

Transistor junctions monitor temperature zones -  12/31/69 EDN Design Ideas:   A simple circuit uses transistor junctions to monitor multiple temperature zones.  The temperature sensors are ordinary, general-purpose, low-cost, diode-connected transistors.  The well-known diode equation VBE = (kT/q) 'ln (IC  /iS) shows that there is a temperature dependency of approximately 2.2 mV/°C for a base-emitter junction.   __ Circuit Design by Matt Smith, Analog Devices, Limerick, Ireland

Transistor Polarity Checker -  Presented here is a simple circuit that will help you figure out whether a transistor is npn or pnp type.  if the transistor under test is npn, red LED will blink....__ Electronics Projects for You

Transistor quickly wakes sleeping LDO -  09/01/98 EDN Design Ideas:  NOTE:     FILE
has many circuits, scroll down.  Portable systems, such as telephone handsets, make extensive use of low-dropout (LDO) regulators.  These components provide noise-sensitive parts with a stable power-supply line.  When a telephone enters standby mode, most of the circuits go to sleep by disabling the LDO's outputs.  Operating current thus drops to a minimal level.  When a user starts to dial a number, the LDO receives an enable signal and immediately delivers the nominal operating voltage.  Unfortunately, most low-noise LDOs use a bypass capacitor that briefly loads the internal reference voltage upon wake-up. __ Circuit Design by Christophe Basso, Motorola Semiconductor, Toulouse, France

Transistor Spot Checker -  The simple transistor spot checker is one of the most handy gadgets on the experimenter's workbench, especially if said experimenter has numerous surplus transistors with unknown histories or mysterious "in-house" part numbers.  A quick check can confirm that the problem lies elsewhere when a new circuit fails to function properly or help jog the memory on whether a 2N2905 is NPN or PNP without a trip to the data book.  The following schematic is of a tester I made about 30 years ago. (Yes, they had transistors back then.)  __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Transistor Tester -  You can test both npn and pnp transistors using this circuit.  The circuit indicates whether the transistor is good, open or shorted through two light-emitting diodes (LEDs). The circuit comprises two NE555...__ Electronics Projects for You

Transistor Tester -  You can test both npn and pnp transistors using this circuit.  The circuit indicates whether the transistor is good, open or shorted through two light-emitting diodes (LEDs).   __ Contact IQ Technologies

Transistor Tester -  This simple circuit has helped me out on many occasions.  it is able to check transistors, in the circuit, down to 40 ohms across the collector-base or base-emitter junctions.  it can also check the output power transistors on __ Designed by Randy Linscott

Transistor Tester & Signal injector -  There have been a lot of transistor tester circuits in recent electronics magazines, but this one is different.  it has more features and includes a signal injector so you can test audio sections of radios and the front end of FM transmitters etc __ Contact Collin Mitchell

Transistor tester fits into your pocket -  20-Dec-01 EDN Design Ideas:  it can be heLPFul to rapidly and easily determine the polarity (npn or pnp] and function of a transistor.  The pocket-transistor tester in Figure 1 is ideal for quickly testing without regard to such parameters as gain and frequency response.  You connect the transistor, or device under test, between the collectors, T, of an astable multivibrator __ Circuit Design by Jean-Bernard Guiot, DCS AG, Allschwil, Switzerland

Transistor Tester Identifies Terminals -  03/17/11  EDN Design Ideas:  it also lets you determine if a transistor is an NPN or PNP type.   __ Circuit Design by Raju R Baddi, Tata Institute of Fundamental Research, Maharashtra, India

Transistor Trio Makes Vector Anemometer -  09/01/97 EDN Design Ideas:  A previously published Design idea (Reference 1] uses a heated transistor as an airspeed-to-frequency converter.  Because it uses only one transistor, the circuit cannot determine the direction of airflow.  Alternatively,  __ Circuit Design by W Stephen Woodward, Chemistry Department, University of North Carolina--Chapel Hill

Transistor & FVCs Make Linear Anemometer -  09/26/96 EDN Design Ideas:  The basic operation of this front-end sensor is identical to that of the earlier circuit.  Q1 is the self-heated airflow sensor; Q2 senses ambient temperature.  Zero-adjust resistor R2 sets the zero-airflow quiescen __ Circuit Design by Steve Woodward

Transistorised Logic Probe for Ttl -  A logic probe is a handheld pen-like probe used for analysing and troubleshooting the logical states '0' or '1' of a digital circuit.  While most logic probes are powered by the...__ Electronics Projects for You

Transistors offer thermal protection for controller -  07/19/01 EDN Design Ideas:  When a switch-mode power-supply controller, such as On Semiconductor's NCP1200, operates at a high ambient temperature, you should protect the entire power supply against lethal thermal runaway.  The NCP1200 operates directly from the power mains without an auxiliary winding; therefore, the die in the IC dissipates power (Figure 1)  __ Circuit Design by Christopher Basso, On Semiconductor, Toulouse, France

Transistor-Switch Detects Audio Signal -  For some audio systems it is desirable to have an automatic switch circuit turn on other devices, such as an amplifier, if an audio signal is detected on one line.  The hobby circuit below will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.  The switch could be used to turn on a relay, routing the signal to where it is needed.  A single 3v lithium cell will power the electronic circuit for about 5 years . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

Transition Counter Gauges Thermal Stability -  01/04/96 EDN Design Ideas:  The transition count of Figure 1is an easy way to determine if the temperature in a heater is stable.  The stable state maximizes the transitions.  This circuit works like a digital filter with controlled frequencies and is simpler than many other analog- and digital-circuit alternatives __ Circuit Design by Jose Luis Arce, Tecnosuma Havana, Cuba

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

 


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