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Tester or Measurement (Instrument) Circuits

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Last Updated: November 22, 2021 02:42 PM
Circuits Designed by Dave Johnson, P.E. :

Piezoelectric Vibration Sensor Activates Switch -  An inexpensive piezo device is used as a motion sensing device for this motion alarm. . . Circuit by Dave Johnson P.E.-July, 2006

Piezoelectric Water Flowing Indicator -  The vibrations associated with water flowing through a pipe are picked up by an inexpensive piezo wafer.  The signal from the wafer is first boosted by a micropower transistor amplifier and then fed to an ultra low power voltage comparator . . . Hobby Circuit designed by David Johnson P.E.-July, 2009

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:

Philips GM 7633/01 Cartomatic III tube Tester schematic -  vintage television (schematic)  __ Designed by Frank Pocnet

Philips PW 4029 regulated power supply schematic -  vintage television (schematic)  __ Designed by Frank Pocnet

Phone Busy Indicator -  Simple busy indicator, does not meet regulations of many countries because this circuit draws excessive continuous current from the ph1-line even when not active and this can cause problems with Telephone system.   __ Designed by Aaron Cake

Phone Line Polarity Checker -  Do you suspect your broadband speed (DSL) is slower than it should be? it could be as simple as incorrect polarity in your phone wall socket.  Build this very cheap, very simple device to find out whether you need to change your wiring! __ SiliconChip

Phone-line-voltage Monitor meets FCC specs -  19-Aug-04 EDN Design Ideas:  When you design equipment that interfaces to a phone line, it is often desirable to be able to monitor the dc voltage on the line.  This ability can be useful, for example, to determine whether a line is in use before attempting to go off-hook and possibly interrupting somebody's phone call.  FCC regulations place strict limits on the amount of leakage current an on-hook device can draw from a ph Design by Brad Peeters, Theta Engineering, Costa Mesa, CA

Photo Meter Assesses Ambient Light -  10/15/12  EDN Design Ideas:  When most PN-junction diodes are reverse biased, they will produce a small photovoltaic output as the light level is increased.  Most PN-junction diodes can be used as photodiodes.  While not optimized for this application, they do work.  When the diode is reverse biased, it will produce a small photovoltaic output as the light level is increased.  LEDs are particularly suited for this task because their housings are transparent Design by Raju Baddi

Photo Tour of a Bird Wattmeter Element -  Ever wonder what's inside one of those elements?  __ Designed by Robert W. Meister WA1MIK

Photoelectric-FET Optocoupler as a Linear Voltage-Controlled Potentiometer -  01/19/12 EDN Design Ideas:  The circuit takes advantage of an identical photo-FET as a feedback element.  You can use a photoelectric FET as a variable resistor or a potentiometer in combination with a fixed resistor.  The H11F3M photoelectric FET has an isolation voltage of 7.5 kV, enabling you to safely control highvoltage circuit parameters.  The nonlinear-transfer characteristics of these devices are problematic, however (Figure 1).  To correct the nonlinearity, using a simple feedback mechanism as a potentiometer yields a linear response (Figure 2).  This circuit uses two photoelectric FETs—one for feedback and the other for applications requiring an isolated potentiometer.  You connect the inputs of the two photoelectric FETs in series to ensure the same amount of current for the input LEDs.   Design by Sajjad Haidar, University of British Columbia, Vancouver, BC, Canada

Photometer -  An illuminance of 100 to 1000 lux is required for reading and doing close work without eye-strain.  Specular illumination or bright sunlight provides 50, 000 lux, while twilight or dim light provides ...__ Electronics Projects for You

Photoresistor Provides Negative Feedback to an Op Amp, Producing a Linear Response -  05/27/10 EDN Design Ideas:  A photoresistor, as part of an optocoupler, provide as negative feedback to an op amp, producing a linear response - AGC (automatic-gain-control] amplifiers use the nonlinear characteristics of control devices.  The magnitude of the real component in some of their differential parameters changes depending on variations in their dc operating points.  A typical example is the VA characteristic of a silicon PN junction, which results in the differential conductance directly proportional to the passing dc current (Reference 1].  in this form of control, the main problem is the control element's nonlinear transfer characteristic, which causes Design by Julius Foit and Jan Novak, Czech Technical University, Prague, Czech Republic

PIC based digital voltmeter (DVM) -  This project will describe how to make a simple digital voltmeter (DVM) using a PIC 16F688 microcontroller.  The range of this DVM is 0-20V, but you can easily increase or decrease the range of input voltage as your requirements after you understand the voltage scaling method described in this project.  The PIC  micro reads the input voltage through one of the 8 analog channels and convert it to a 10-bit digital number using the internal ADC __ Contact Raj Bhatt & Shawon Shahryiar

PIC Frequency Counter -  Programmable frequency meter with PIC 16F84 and UPB1505 prescaler __ Designed by YO5OFH, Csaba Gajdos

PIC Logic Probe with Pulser -  This project is a combinationLogic Probe and Logic Pulser.  it is capable of testing all sorts of digital and microcomputer projects.  You will find it extremely handy when designing a project as the golden rule is totest everything in steps and stages during the design-and-construction process.  if you are not sure how a Logic Probe or Pulser works __ Designed by Prepared Colin Mitchell

PIC NiCad Battery Charger -  This cheap and easy to build NIC d/NiMH Battery Charger is suitable for automatically charging a wide range of batteries for many applications.  Proper chargers are usually expensive and cheap chargers supplied with the original equipment often incorrectly charge the cells and dramatically shorten their life __ Designed by Peter Hayles

PIC RJ-45 Cable Tester -  This RJ-45 cable tester automatically checks cable continuity and tests the connection configuration.  Each of the eight connections is checked independently and short-circuits are detected.  The circuit can be built using either a PIC 16C62B or a PIC 16F72must register on this site __ Designed by Published in Elecktor July/Aug, 2010

PIC16F84 Debugging Terminal -  Build a simple 9600 BAUD 8n1 LCD terminal for debugging and testing the projects having RS232C output __ Designed by M Asim Khan  asimkhan @ sat.net.pk

PIC16F84A 3.5GHz LCD Frequency Counter -  This Auto Ranging PIC 16F84A Frequency counter counts up to 35-40Mhz and has two separate input BNC connectors.  A pre-scale chip from Nec/CEL may be added with Divide by 256 counters to achieve 3.5GHZ frequency measurements.  __ 

PIC16F84A Gas Detector using GH-312 SENSOR -  This is a gas detecting circuit capable of sensing many different types of gases.   The sensor used is the GH-312 and from the datasheet it is capable of sensing gases like smoke, liquefied gas, butane and propane, Methane, alcohol, hydrogen, etc.__ 

PIC16F877 APRS Weather Station -  Weather Station is PIC 16F877A based and has a 4x20 LCD, a data logger output and accepts 1Wire wind instrument.  it has a built-in APRS TNC.  Connect it to your portable rig thru a DiN5 connector and you have a true portable weather station.  __ 

PIC16f877a-Based Temperature Monitoring System -  Temperature monitoring and control is important in industry environments.  Sensors are widely used for measurement of temperature.  Usually, a temperature sensor converts the temperature into an equivalent voltage output.  IC LM35...__ Electronics Projects for You

PicAXE Ionization Chamber -  This simple radiation detector uses a PicAXE-08M microprocessor to measure the voltage drift rate on an ionization chamber's sense wire, eliminating the need for a high-value resistor.  An electrometer-grade JFET is used to buffer the voltage on a sense wire inside the chamber, and a PicAXE microprocessor measures the rate of change of that voltage, periodically discharging the wire through the JFET's gate-source junction.  This unorthodox way of discharging the ion chamber wire eliminates the need for a special, low-leakage switch, and takes advantage of the PicAXE's ability to use the same pin as an analog input or a digital output.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

PIC-DAS, a PIC based Data Acquisition System -  The PIC  DAS was designed to fill a very real need which I always have in the Lab, which is: "How do I quickly read some data or control some hardware when the whole system isn't available?" I solved this with the PIC  DAS a PIC  based data acquisition system.  The PIC  DAS contains a PIC  Microcontroller __ Designed by Steve Hageman

Picoammeter with 4 ranges  -  This circuit uses a CA3420 BiMOS op amp to form a picoammeter with 4 ranges.  The exceptionally low input current (typically 0.2pA) makes the CA3420 highly suited for use in a picoammeter circuit.  input transient protection is provided by the 1 megohm resistor in series with the input.  The 10 megohm resistor connected to pin 2 decouples the potentially high input capacitance often associated with lower current circuits and reduces the tendency for the circuit to oscillate under these conditions.  The 10k potentiometer is used for null offset. __ Contact IQ Technologies

Picoampere Leakage Tester

Pictures of My Pulse-1 & 2 Metal Detector Project -  These Detectors have been Built by Various Persons, And I included their Comments on it's performance.   __ Designed by G.L. Chemelec

PID Temperature Controller -  What's a PiD controller? PiD stands for "proportional integral differential" and relates to a process which seeks to continuously correct the error between a measured variable and a desired setting by calculating an appropriate correction process.  in practice, it can largely avoid the large overshoots and undershoots that occur in simple temerature control systems.__ SiliconChip

Piezo crystal Monitors liquid level -  03/30/00 EDN Design Ideas:  The simple and inexpensive circuit in Figure 1 monitors the liquid level in a container.  The piezo crystal, carefully mounted at the bottom surface of the container, receives it activation from the 74HCT14 hex Schmitt trigger.  The.   PDF contains multiple circuits, please scroll to find this one Design by J Jayapandian, IGCAR, Tamil Nadu, India

Piezoelectric Vibration Sensor Activates Switch -  An inexpensive piezo device is used as a motion sensing device for this motion alarm. . . Circuit by Dave Johnson P.E.-July, 2006

Piezoelectric Water Flowing Indicator -  The vibrations associated with water flowing through a pipe are picked up by an inexpensive piezo wafer.  The signal from the wafer is first boosted by a micropower transistor amplifier and then fed to an ultra low power voltage comparator . . . Hobby Circuit designed by David Johnson P.E.-July, 2009

Pills Reminder -  4 - 6 - 8 - 12 - 24 - 48 hours setting; LED or Beep Alert - 9V Battery Supply __ Contact Flavio Dellepiane, fladello @ tin.it

Pills reminder Alarm using CMOS logic gates -  A Pills Reminder is a device that operates a flashing LED (and/or a beeper) at a fixed hour interval.  A choice of time-intervals as wide as possible is available with this circuit, namely 4, 6, 8, 12, 24 and 48 hours.  At first you must choose the hour interval by switching SW1 to the desired value, then apply power by means of SW2.  After the hour delay chosen has elapsed the LED will start flashing at 2Hz, i.e.  two times per second__ Learning Electronics

Pink Noise Generator for Audio Testing -  For loudspeaker and room acoustics testing ( __ Designed by Rod Elliott  ESP

PIR Camera -  A simple automatic motion-detection Digital Camera.   __ Contact Collin Mitchell

Plant Moisture Monitor -  Originally intended to monitor the moisture in a potted plant, this moisture monitor really shines as a Christmas tree stand water level monitor!  A fresh Christmas tree drinks water an annoying rate and bending down under the __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Plant watering timer -  it's time to automate the watering of your garden, balcony, or that azalea in your living room!  __ Designed by Manfred Mornhinweg

Plant Watering Watcher -  This circuit is intended to signal when a plant needs water.  A LED flashes at a low rate when the ground in the flower-pot is too dry, turning off when the moisture level is increasing.  Adjusting R2 will allow the user to adapt the sensitivity of the circuit for different grounds, pots and probe types.
__ Learning Electronics

Plant Watering Watcher -  A flashing LED signals the necessity to water a plant; Very low current consumption - 3V powered circuit __ Contact Flavio Dellepiane, fladello @ tin.it

Plants Watering Watcher 2 -  IC 1D is a CMOS Schmitt trigger oscillator at about 2KHz.  it starts and continues to oscillate with a supply down to 1.24V (the lowest output voltage of my LM317 variable power supply) or less;  IC 1A is an inverter;  IC 1B is a Schmitt trigger NAND gate.  its output is low only when both inputs are at, or higher than the upper Schmitt trigger threshold voltage.  With 47 ohms or less between the probes, an input is always low, so the output is always high. __ Contact IQ Technologies

Platinum RTD Digitizer Accurate within 1° Over 0°C to 100°C -  Platinum RTD Value is Linearly Converted to Period by LTC1799.  Logic and Second LTC1799 Clock Digitize Period into Output Data Bursts.  Bootstrapping Pin Capacitance is used to Permit Remotely Located Sensor.  __ Linear Technology/Analog Devices App Note, Apr 7th 2010

Platinum RTD Signal Conditioner with Curvature Correction -  The left stage forms a stable precision current source by establishing the reference voltage across a precision resistor, and about half of this current passes through the sensor.  The right OpAmp provides an amplification of the resistance difference between the sensor and a fixed precision resistor to generate a temperature__ Linear Technology/Analog Devices App Note, Jun 21, 2011

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

Pocket TENS Unit for Pain Relief -  Little Jim AM Transmitter__ SiliconChip

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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

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