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Probe Circuits
#'s - L      M - Z

 

Last Updated: October 24, 2017 02:55 PM

Circuits Designed by Dave Johnson, P.E. :
X100 Scope Probe - Often a typical X10 oscilloscope probe will produce large measurement errors and will influence the circuit operation.  To reduce the effect such a probe has on the circuit, I reach for my X100 scope probe, with its 100M impedance.  This probe is a commercially made device but if you want to make one, it is not hard to do.. . . Circuit by David A. Johnson P.E.-May, 2010

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:

Magnetic-field probe requires few components-  12/15/06  EDN Design Ideas:  Hall-effect sensor and DMM explore stray fields __ Circuit Design by Sandeep M Satav and VV Rama Sarma, EMI-EMC Centre, RCI, Hyderabad, India

Making Differential Probes-  For sensing audio signal voltages across devices that are not ground referenced__ Liberty Instruments, Inc

Modified Scope Probe Tests Surface Mount Assemblies-  09/25/97 EDN Design Ideas:  The small sizes and pad areas of surface-mount components make them difficult to probe.  Typically, when you use an oscilloscope probe, it is difficult to keep the probe tip and ground bayonet from slipping off the pad areas of the surface-mount devices.  The modified oscilloscope probe __ Circuit Design by Robert Buono, Mahwah, NJ

Precision Audio Frequency Peak Detection Probe -  This is a handy companion for a digital voltmeter.  Its allowed me to do a lot of things I used to use my oscilloscope for, and in addition it measures voltages to much greater precision.  Using an LM324 quad op amp, this peak detector provides 2% measurement accuracy on square waves from 5 Hz to 20 kHz. __ Designed by Dick Cappels

Precision Wideband Current Probe for LCD Backlight Measurement-  DN101 Design Notes__ Linear Technology/Analog Devices

Probe measures high frequencies-  01/18/96 EDN Design Ideas:  Measuring clocks and critical signals accurately is often inconvenient.  Normal 10x probes usually have about 10 pF of input capacitance, which can considerably affect the signal.  FET probes with 1 to 3 pF of input capacitance are expensive and often require an extra power supply or other special setup.  Unless ground leads are short (10 to 20 mm) , these leads introduce considerable distortion to most probes. __ Circuit Design by Glenn J Keller,  The 3DO Company, Redwood City, CA

Probing System Lets You Test Digital ICs-  06/20/12  EDN Design Ideas:  Build a test jig and a combination logic and stimulus injector probe. __ Circuit Design by Raju Baddi, Tata Institute of Fundamental Research, Pune, India

Probing the Limits Of LOGIC SYNTHESIS-  03/17/94 EDN Design Ideas:  Logic synthesis has freed designers from the complexities of gate-level design by converting RTL descriptions to optimized gate-level logic.  But ASIC, FPGA, and CPLD designers are still constrained by a dependence on silicon.  Designers will need to pay more-not less-attention to layout as silicon densities continue to increase. __ Circuit Design by -Ray Weiss, Technical Editor

Pulse Generator Verifies Test Setups-  05/26/94 EDN Design Ideas:  Verifying the rise-time limit of wideband test-equipment setups is a difficult task.  In particular, you must often know the "end-to-end" rise time of an oscilloscope/probe combination to ensure measurement integrity.  Fig1s circuit provide as an 800-psec pulse having rise __ Circuit Design by Jim Williams, EDN's most revered contributor, passed away in June 2011 after a stroke.  He was 63.

Pulse Reading Logic Probe-  This circuit uses LEDs to display logic states for high, low, rising pulse, and falling pulse, it is generally useful for debugging logic circuitry. __ Designed by G. Forrest Cook

RF Field Strength Probe-  This broadband probe has a small antenna ( about a 15 cm length of insulated wire).  Radio Frequency energy coupled to the antenna is detected and made available to drive millivolt level signals to the input of a DVM ( Digital Volt Meter).  Its battery powered for convenience with very low current drain and automatic shutdown for long battery life. __ Designed by Dick Cappels

Scope probe measures high frequencies-  01/18/96 EDN Design Ideas:  Measuring clocks and critical signals accurately is often inconvenient.  Normal 10x probes usually have about 10 pF of input capacitance, which can considerably affect the signal.  FET probes with 1 to 3 pF of input capacitance are expensive and often require an extra power supply or other special setup.  Unless ground leads are short (10 to 20 mm) , these leads introduce considerable distortion to most probes. __ Circuit Design by Glenn J Keller,  The 3DO Company, Redwood City, CA

Simple Circuit Diode Serves as a Sensor for a Thermal Probe-  02/16/12  EDN Design Ideas:  A two-transistor thermal probe can be used to diagnose circuit problems, such as hot components and thermal runaway. __ Circuit Design by Raju Baddi, Tata Institute of Fundamental Research, Pune, India

Simple Circuit Logic Probe uses Bicolor LED-  03/13/98 EDN Ideas - (   FILE has several circuits, scroll to this one) A project posed the challenge of replacing existing analog potentiometers (used to set brightness and contrast levels]in video monitors with digitally controlled potentiometers.  The different brands and models of monitors presented widely varying voltages across the potentiometers.  The design. __ Circuit Design by Mark Shill, Burr-Brown Corp, Tucson, AZ

Simple Circuit RF Probe-  Indispensable for any RF work.  Uses just 4 passive components __ Designed by Rod Elliott  ESP

Super Probe, 16 functions with very few parts-  The Superprobe project was designed to see how much could be done with a PIC chip and just a few parts.  The image at the right shows the capacitance measuring mode.  This device is designed around a PIC16F870, a 4 digit LED display module and very little else.  [img:eb8cceb438]http://www.  circuit dB.  com/download.  php?fileID=135[/img:eb8cceb438] [i:eb8cceb438]Note: I have received a lot of inquiries on this project.  To date, several have been duplicated world-wide.  Many have been constructed in other types of cases.  As long as the circuit is wired as shown, and the object code ( below) is__

Switchable RF Probe/Watt Meter for the FM Transmitters-  This unique project is one of the most trusted homemade test instruments to have, once you get your FM transmitter up and running ! ! !This simple little device is capable of finding your FM transmitters' __ Designed by braincambre500 @ yahoo.com

The Curious C-Beeper-  The Curious C-Beeper uses the two-transistor flasher in conjunction with a Darlington transistor to make a most unusual capacitance beeper probe.  When a capacitor is touched to the probe, the probe beeps at a frequency that varies with capacitance.  The frequency change is so steep with capacitance that tiny capacitors may be precisely matched or an exact fixed value may be selected to replace a trimmer in a prototype.  If the user has reasonably moist skin, simply holding one lead of the capacitor to be tested while touching the other lead to the probe is all that is necessary.  The user's body forms the other connection through the beeper's metal case. __ Contact:  Charles Wenzel of Wenzel Associates, Inc.

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

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

TTL pulse counter/logic probe-  When building and troubleshooting TTL circuits, I've used this thing more than just about any other tool.  I needed something that could detect whether a pulse was occurring on a signal line, and just as importantly, whether more than one pulse occurred or not. __ Designed by Frank Crivelli & Peter Crowcroft

TTL Pulse Reading Logic Probe-  This circuit uses LEDs to display logic states for high, low, rising pulse, and falling pulse, it is generally useful for debugging logic circuitry. __ Designed by G. Forrest Cook

TTL/CMOS Logic Probe1 with Pulse-  One of the most frustrating problems with experimenting is not be able to check the logic state of TTL or CMOS ic's without the use of a triggered oscilloscope. The schematic diagram above shows a simple and inexpensive way of building a 'Logic Probe' yourself. It will provide you with three visible indicators; "Logic 1" ( +, red led) , "Logic 0" ( -, green led) , and "Pulse" ( yellow led) __ Designed by Tony van Roon  VA3AVR

TTL/CMOS Logic Probe2-  This circuit uses the four 2 input NOR gates contained within the 4001 CMOS IC, and is primarily intended for testing CMOS circuits.  The probe derives its power from the supply of the circuit being tested.  The first gate, N1, has its inputs tied together so that it operates as an inverter, and it is biased by R1 so that roughly half the supply potential appears at its output __ Designed by Tony van Roon  VA3AVR

TTL/CMOS Logic Probe3-  A logic tester with an audible indicator can be handy when troubleshooting or testing a crowded circuit board.  It allows you to keep your eyes on the circuit, rather than on a LED on the tester.  The project described in this article is just such a tester.  It provides an audible indication of the logic level of the signal presented to its input __ Designed by Tony van Roon  VA3AVR

Ultra-Simple Circuit Voltage Probe-  Detects 1.8 to 230 Volts DC or AC Minimum parts counting.  Circuit diagram: Parts: D1 5 or 3mm.  Red LED D2 5 or 3mm.  Green or Yellow LED LP1 220V 6W Filament Lamp Bulb P1 Red Probe P2 Black Probe Device purpose: This circuit is not a novelty, but it __ Designed by Flavio Dellepiane

Versatile CMOS /TTL Logic & Clock Probe-  For fault diagnosis of any logic circuit, you need a probe that can test the logic level or existence of clock activity.  The circuit shown here can be used to test...__ Electronics Projects for You

Versatile Probe-  You can use this versatile probe for continuity testing and identification of transistor type and transformer windings.  The n-side or p-side of a transistor can be identified quickly in one go....__ Electronics Projects for You

Vibration Activated smart CRO probe-  This is a simple, low-cost, energy-saving and device-saving circuit for an electronics lab, service centre, electronics workshop, or wherever a CRO is in use.  Generally, in a repair station, a CRO is used for a very short time.  But in most cases, the user fails to switch off the CRO immediately after use.  The service engineer mostly concentrates on faults rather than noticing whether the CRO is on or off. A vibration sensor turns the CRO off when the probe is idle for a specified amount of time.__ Electronics Projects for You

Voltage Probe-  This circuit is not a novelty, but it proved so useful, simple and cheap that it is worth building.  When the positive ( Red) probe is connected to a DC positive voltage and the Black probe to the negative, the Red LED will illuminate.  Reversing polarities the Green LED will illuminate.  Connecting the probes to an AC source both LEDs will go on. __ Contact Flavio Dellepiane, fladello @ tin.it

White LED Light Probe for Inspection-  This circuit is useful for inspecting narrow spaces like the inside of the CPUs, monitors, PCB modules and other electronic devices.  The light source is a pencil-thin tube with ultra-bright white...__ Electronics Projects for You

X100 Scope Probe-  Often a typical X10 oscilloscope probe will produce large measurement errors and will influence the circuit operation.  To reduce the effect such a probe has on the circuit, I reach for my X100 scope probe, with its 100M impedance.  This probe is a commercially made device but if you want to make one, it is not hard to do.. . . Circuit by David A. Johnson P.E.-May, 2010


Probe Circuits:  #'s - L      M - Z

 


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