Electronic Circuits and electronic circuits, electronic schematics plus an extensive resource for hobbyists, inventors and engineers

DiscoverCircuits.com, has 45,000+ electronic circuits, cross-referenced into 500+ categories.
We have searched the web to help you find quick solutions & design ideas.

Got Designs?
Please eMail
if you want me to link to and/or post your original design
NOTE:  We make every effort to link to original material posted by the designer. 
Please contact us if our link is not to your site!  Thanks.

Tester or Measurement (Instrument) Circuits

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

Last Updated: November 22, 2021 03:00 PM
Circuits Designed by Dave Johnson, P.E. :
Temperature Sensor MOSFET -  Recently I was asked by a company to discover why one of their products failed to operate properly in cold temperatures.  Two n-channel MOSFETs and a few resistors are wired to form a flip/flop latch circuit.  Each time the pushbutton switch is pressed, the circuit changes state and remains in that state until another activation of the switch.. . . Circuit by David A. Johnson P.E.-December, 2010

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-778-8407

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

T3SE - Type 3 (charge rate controlled) Solar Engines

Tablet Reminder that Uses Watch Module -  This device is used as a reminder to take medicine every day.  This device actually contains a crystal watch and a 4001 quad 2-input NOR gate with two of the gates (IC 1a & IC 1b) wired as an RS flipflop.  The watch is set to "tablet time", usually mornings, when an alarm is activated with a high signal fed via diode D1 which sets the RS flipflop and enables the oscillator comprising gates IC 1c & IC 1d. __ Designed by Rasim Kucalovic

Tachometer -  A tachometer is an instrument that measures the rotational speed of a shaft or disk in a motor or other machine.  Here we present the basic version of the tachometer that shows the revolutions per second (RPS) on a digital display.   __ Designed by Najib Ghatte

Tachometer -  A simple tachometer circuit using one NPN transistor.   __ Designed by Jose Pino

Tachometer -  Here is a simple circuit that can be used as a tachometer.  The circuit is basically a frequency to current converter which converts the incoming signal into a proportional current to drive the meter.  The deflection on the ammeter will __ Designed by Jose Pino

Tachometer Demodulator Has Fast Response Time -  12/07/95 EDN Design Ideas:   When a tachometer is a critical part of overspeed-shutdown circuitry, the response time of conventional demodulators may be too long.  The circuit in the block diagram in Figure 1 provide as updated speed data.  The circuit provide as corrections for variations in excitation amplitude and frequency Design by Ed Guenther, Tektronix Redmond, OR

Tachometer for Bikes  -  Here are some instructions how to connect the Tachometer version iI to a single cylinder.   __ Designed by Jose Pino

Tachometer/RPM -  Easy to build using only a few components.  With some modifications, it can be used in an automovil.  This Tachometer uses a PIC  16F628.   __ Designed by Jose Pino

Tachometer/RPM II -  This is an improved version of the Tachometer created specially to measure up to 9, 999 RPM.  Uses a PIC  16F628.   __ Designed by Jose Pino

Tack a log taper onto a digital potentiometer -  01/20/00 EDN Design Ideas:  it's sometimes convenient to have digital control of the volume level in an audio system.  The use of multiplying DACs (MDACs) is problematic because of the switching noise of the ladder network.  This noise comes from the bit switches injecting charge into the signal when they turn on and off.  Audio Design by Hank Zumbahlen, Analog Devices, Campbell, CA

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 , as well as pulse width modulation (PWM) for analogue output.  This project also illustrates how to squeeze every last word of program memory out of a PIC !  Sound samples consume almost all of the on-chip flash memory, and even that was after some pretty brutal trimming of the samples and a drop in resolution to seven bits.  Even after all that, the samples are about as brief as you can get without becoming unrecognisable __ Contact Karen's Microprocessor Projects

Taming of the slew -  09/25/03  EDN Technical Article: Deriving a slew-rate-measurement approach requires understanding slew rate's relationship to amplifier Dynamics. Design by Jim Williams, EDN's most revered contributor, passed away in June 2011 after a stroke.  He was 63.

Tan Timer -  Six timing positions suited to different skin types Timing affected by sunlight intensity Circuit diagram: Parts: R1 47K 1/4W Resistor R2 1M 1/4W Resistor R3, R5 120K 1/4W Resistors R4 Photo resistor (any type) C1, C3 10µF 25V Electrolytic __ Contact IQ Technologies

Tank Water Level Indicator -  A little over five years ago, before water became a "cause celebre", we published a design for a simple tank water level indicator.  Now, with thousands of home water tanks being installed every year (and prompted by many requests for such a project) , we thought it time to resurrect the idea, albeit with a couple of tweaks.__ SiliconChip

TDR cable reflection tester (Time Domain Reflectometer) -  Brief description of operation: Pulse source for time domain reflecometry;  Circuit protection: Output is short circuit proof;  Circuit complexity: Simple one IC construction, can be built on small piece of veroboard;  Circuit performance: Works very well with cables from 5 meters to 500 meters (no longer cables tested, should work for up to kilometers according the original article)  __ Designed by Tomi Engdahl

TDR Test System-WA0PIA -  Schematic only __ Designed by va3iul

TDS/PPM Meter for measuring of the AM ount of salts in a solution -  TDS is the measuring of the amount of salts in a solution.  For alot of applications the amount of salt is indicitive of the levels of other stuff in a solution.  TDS/PPM meters sold for gardening and aquariums figure the amount of salt in Parts Per Million by measuring the Electrical Conductivity of the solution under test.  So a PPM/TDS meter is a EC meter that converts the EC value into PPM values.  There are alot of descriptions online about why and how to measure PPM/TDS or EC so google for them if you want alot more details. __ Designed by isabellal @ tcniso . Net

Technique Measures Small Capacitance -  09/01/97 EDN Design Ideas:  A simple technique (Figure 1) can measure small capacitance, such as the capacitance of a scope probe (Figure 3a) , a 10-pF capacitor (Figure 3b) , and a pc-board trace (Figure 3c).  The idea is to use a ramp generator and an oscilloscope (Figure 1a) to measure the delay in the ramp that corresponds to the capacitance.  Equations provide the best explanation of how the technique works.  For the circuit in Figure 1b, which drI ves channel 2 of the oscilloscope,  Design by Rich Kochis and Joe Eccher, Hewlett-Packard, Greeley, CO

Telephone Call Meter using Calculator & Cob -  in this circuit, a simple calculator, in conjunction with a COB (chip-onboard) from an analogue quartz clock, is used to make a telephone call meter.  The calculator enables conversion of STD/...__ Electronics Projects for You

Telephone line Monitor -  if you feel that somebody is tampering with your telephone line you might find this little circuit useful.  it detects if there is another telephone connected to the line, if there is a short or an open line.  Sound and a flashing light will tell you which is the current situation.  The speaker is practically cut out during a normal conversation thus preserving privacy, only the LED will flash occasionally.  The circuit does not require any battery and takes the supply from the telephone line itself __ Contact IQ Technologies

Telephone Test with Audio Mixer -  I have used this type of circuits for quick testing of telephone equipment.  This is a quick hack that does not exactly resemble the characteristics of the real telephone network, but is enough for this kind if applications.  if you want better simulation, change the resistor to 600 ohm and increase the power supply voltage.  And by the way you can also feed signals to telephone if you connect the circuit output wires to small amplifier output.   __ Designed by Tomi Engdahl

TempBug-- Internet-Connected Thermometer -  26-Jun-14 -Design News:   Last January, we had some trouble with the heat in my office -- specifically, the kind of trouble wherein the heat is not on, you turn it up, and it is still not on.  This went on for more than a few days and finally ended a day or two after we got an email announcing that the heat was broken and __  Gadget Freak-Case #257

Temperature & Voltage Measurement in a Single Chip LTC1392 -  DN106 Design Notes__ Linear Technology/Analog Devices

Temperature Alarm -  A simple op-amp circuit that will trigger a relay when a preset temperature is reached.  Please note that there is no hysteresis in this circuit, so that if the temperature changes rapidly, then the relay may switch rapidly.   __ Designed by Andy Collison

Temperature Candle Using LED -  LED based projects require a lot of skill and hence only experienced circuit designers try out these circuits.  But there are also a few circuits in this genre that can be done by amateur electronic hobbyists.  The temperature candle is one such circuit.  Read on to know more about this.  The hardware components that are__ 

Temperature Controled Fan -  This circuit controls very accurately a fan of any size.    Just adjust the associated resistors for a different type and you're all set.    The above circuit diagram is for a small cpu-fan, rated 12V at 12mA current.   __ Designed by Tony van Roon  VA3AVR

Temperature Controlled NiCad Charger -  This circuit is for a temperature controlled constant current battery charger.  it works with NIC D, NiMH , and other rechargeable cells.  The circuit works on the principle that most rechargeable batteries show an increase in temperature when the cells becomes fully charged.  Overcharging is one of the main causes of short cell life, hot cells pop their internal seals and vent out electrolyte.  As cells dry out, they lose capacity.  This circuit can quickly charge a rechargeable battery pack without any negative effects.  This circuit uses a 22VDC power supply, my version 2 circuit will run from a 12VDC supply such as a solar-powered or automobile power system. __ Designed by G. Forrest Cook

Temperature Controlled Ovens -  Here is a simple temperature controller suitable for a variety of purposes; it was designed to heat the copper float out of a toilet for a barometer!  __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Temperature Controller Drives Peltier Cooler -  06/08/95 EDN Design Ideas:  The circuit in "Peltier element controls itself, " by DmitriI Loukianov (EDN, October 27, 1994, pg 86) is elegant, but it suffers from two potential problems that could arise in some applications.  The first is possible switching-noise injection from capacitive and inductive coupling at the front end of a sensitive analog-signal-conditioning chain (for example, in a CCD-cooling application).  The second potential problem is Peltier-stack performance degradation from intermittent, fast-switching drive current.  At least one UK-based Peltier-cooler manufacturer recommends uninterrupted dc drive.    Design by Dr Trevor Preston, Cambridge, UK

Temperature controller has "take-back-half" convergence algorithm -  09/15/05 EDN Design Ideas:  Enhanced closed-loop control balances stability, responsiveness Design by W Stephen Woodward, University of North Carolina, Chapel Hill, NC

Temperature controller keeps IR Detector at 8şK -  01/07/99 EDN Design Ideas:  Sensitive infrared array detectors must operate at a low temperature to avoid thermally generated dark current throughout the photoconductive elements.  This requirement is particularly true for SiAs array detectors, which   Page includes several designs.  Scroll to find this one Design by Jerry Penegor, Space Sciences Laboratory, University of California—Berkeley

Temperature controller saves energy -  3-Feb-05 EDN Design Ideas:  Given the high cost of electrical power, replacing a conventional on/off temperature control with a proportional controller can often save energy and money.  Figure 1 shows a low-cost, high-efficiency, time-proportional temperature controller for a residential water heater.  An Analog Devices ADT14, IC 1, serves multiple functions as a temperature sensor, quad-setpoint, programmable analog tempe Design by Tito Smailagich, ENIC, Belgrade, Yugoslavia

Temperature Indicator-Cum-Controller -  Here is an easy-to-construct temperature indicator-cum-controller that can be interfaced with a heater’s coil to maintain the ambient room temperature.  The controller is based on Atmega8535 microcontroller, which makes it dynamic...__ Electronics Projects for You

Temperature Measurement -  Measures temperature via SMT160-30, shows it on LCD and communicates with RS232 (sends values of temperature to terminal __ 

Temperature Measurement using the LTC1090/91/92 Series of Data Acquisition Systems -  DN5 Design Notes__ Linear Technology/Analog Devices

Temperature Monitor for Electronic Equipment -  As most electronics components’ characteristics vary with temperature, they are selected as per expected operating temperature range of the equipment.  So it is important that the equipment stays within the temperature...__ Electronics Projects for You

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; the channel matching and flatness of this resistance normally result in a varying temperature offset.  This system uses the ADT7461 temperature monitor, which can automatically cancel resistances in series with the external temperature sensors, allowing its use as a multichannel temperature monitor.   Design by Susan Pratt, Analog Devices, Limerick, Ireland

Temperature Monitor using 741 opamp -  A simple op-amp circuit that will trigger a relay when a preset temperature is reached.  Please note that there is no hysteresis in this circuit, so that if the temperature changes rapidly, then the relay may switch rapidly.   __ Designed by Andy Collison

Temperature Monitoring with an NTC Thermistor While Measuring Load Current & LTC4151 Supply Current -  The LTC4151 is a high side power monitor that operates over a wide voltage range of 7V to 80V.  in default operation mode, the onboard 12-bit ADC continuously measures high side current, input voltage and an external voltage.  Data is reported through the i2C interface when polled by a host.  The LTC4151 can also perform on-demand__ Linear Technology/Analog Devices App Note, Apr 26th 2010

Temperature Relay -  This simple temperature relay circuit can be used to signal a fire or setpoint for temperature monitoring function.  You need to adjust P1 so that T1′s base voltage is 0.5V smaller than the emitter voltage at a temperature a little bit lower than the desired triggering (switching) temperature.  if the temperature increases __ Designed by Popescu Marian

Temperature Sensitive Switch For Solar Collector -  This circuit can be used to turn the pump on and off when a solar collector is used to heat a swimming pool, for example.  This way the water in the collector has a chance to warm up significantly before it is pumped to the swimming pool.  A bonus is that the pump doesn’t need__ 

Temperature Sensor Control -  A basic circuit using Diodes to detect temperature differences __ Designed by G.L. Chemelec

Temperature Sensor Doesn't Discharge Battery -  08/01/96 EDN-Design ideas The circuit in Fig.1 is useful for precise, repetitive temperature control of small-volume objects.  it offers high resolution and effective isolation between the control lines and the power mains.  it generates no RFi, has adequate speed, and provide as a linear relationship between the digital-input code and the average thermal power supplied by the heater.  The circuit works by generating a programmable number of triggering pulses to a TRIAC connected in series with the heater Design by Jordan Dimitrov, N Poushkarov Institute of Soil Science and Agroecology, Sofia, Bulgaria

Temperature Sensor MOSFET -  Recently I was asked by a company to discover why one of their products failed to operate properly in cold temperatures.  Two n-channel MOSFETs and a few resistors are wired to form a flip/flop latch circuit.  Each time the pushbutton switch is pressed, the circuit changes state and remains in that state until another activation of the switch.. . . Circuit by David A. Johnson P.E.-December, 2010

Temperature Sensor Readout Unit -  This is the fully featured, jammed packed temperature readout unit.  I can measure temperature from up at 8 DS1820 digital temperature sensors all on the same 1-wire bus.  That's right only 3 wires are needed to go to all the temperature sensors, GND, VCC and 1-wire data.  All sensors will connect to the same cable!  Anyone who has used the DS1820's__ 

Got Designs?
Please eMail
if you want me to link to and/or post your original design Thanks.

      <<<         >>> 

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

HOME Schematics Index Hobby Corner Dave's Circuits Contact Info
Imagineering Ezine Dave Johnson, P.E. Faraday Touch Switches

 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |   Link to DiscoverCircuits.com  |  Privacy Policy

Copyright  January, 1998 - November, 2021     David A. Johnson  All Rights reserved. 

 COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED!