Probe Circuits free electronic circuit links

Probe Circuits
Last Updated on: Monday, October 26, 2009 04:53 AM

Circuits Designed by Dave Johnson, P.E. :

BROAD BAND 5MHz OPTICAL FIBER RECEIVER
This circuit is a simple broad band light detector that uses a very inexpensive IC and a PIN photodiode that is packaged for use with plastic optical fibers. It has a bandwidth from 1KHz to over 5MHz. It is great for experimenting with various modulated light sources.

BROAD BAND 2MHz OPTICAL FIBER RECEIVER
If you need more sensitivity than the above circuit this circuit provides about ten times more gain. It too is designed around an inexpensive plastic optical fiber detector.

BROAD BAND 50MHz OPTICAL FIBER RECEIVER VERSION A
If the above circuit it still too slow, you can try this circuit. What it lacks in sensitivity it makes up for in speed. The circuit attaches a plastic fiber optic PIN photodiode assembly to a small box containing a small 3v battery and a standard BNC plug. When the box is plugged into to the input of an oscilloscope with a 50-ohm termination resistor, it can detect light pulse frequencies beyond 100MHz.

LIGHT RECEIVER WORKS FROM 1KHz TO OVER 70MHz
This circuit uses one tiny C-MOS inverter IC to form a modulated light receiver with a very fast response. It is designed around a PIN photo diode that is packaged for use with plastic optical fibers. It can be used as an optical fiber receiver. By using the open end of the optical fiber it can "sniff" out any modulated light signals.

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

A Precision Wideband Current Probe for LCD Backlight Measurement - DN101 Design Notes (Linear Technology) (app note added 1/06)

AN 1404: The Truth About the Fidelity of High Bandwidth Voltage Probes 5988-6515EN - Aligent Application Note (app note added 6/07)

Audible Logic Probe - The probe uses 2 IC's and a handful of components to indicate the state of the input on 3 LEDs while the piezo gives an audible indication of the state of the line. The input is connected to two inverters in the 4049 IC. The top one is held above mid-rail via the 1M trim pot while the bottom one is held below mid rail by the 1M/220k voltage divider....(electronic design added 06/07/08)

Audible Logic Probe - When testing circuits with a logic probe, it is sometimes difficult to watch the LEDS on the probe to determine the logic state. With this probe the logic states are audible. This probe is designed for TTL circuits only but could be modified for CMOS. The way ….(added 08/08/08)

Broad Band 2MHz Optical Fiber Receiver - If you need more sensitivity than the above circuit this circuit provides about ten times more gain. It too is designed around an inexpensive plastic optical fiber detector. ….(designed by David A. Johnson)

Broad Band 50mhz Optical Fiber Receiver Version A - If the above circuit it still too slow, you can try this circuit. What it lacks in sensitivity it makes up for in speed. The circuit attaches a plastic fiber optic PIN photodiode assembly to a small box containing a small 3v battery and a standard BNC plug. When the box is plugged into to the input of an oscilloscope with a 50-ohm termination resistor, it can detect light pulse frequencies beyond 100MHz. ….(designed by David A. Johnson)

Broad Band 5mhz Optical Fiber Receiver - This circuit is a simple broad band light detector that uses a very inexpensive IC and a PIN photodiode that is packaged for use with plastic optical fibers. It has a bandwidth from 1KHz to over 5MHz. It is great for experimenting with various modulated light sources. ….(designed by David A. Johnson)

CDV700 Geiger Counter Probe Rebuilding - (electronic design added 6/07)

CMOS Logic Probe (Tony van Roon) - with probe, CMOS (Tony van Roon's electronic design added 5/05)

Designing High-Speed Digital Systems for Logic Analyzer Probing - Agilent Application Note (added 6/06)

Designing RF Probe - make your self simple and highly useful RF probe. An essential tool for every home brewer. . (added 9/04)

Differential Scope Probe Delivers 6GHz Bandwidth to the Screen - 02/20/03 EDN-Design Ideas: With digital scopes that offer 6-GHz bandwidth suddenly almost commonplace and with industry participants now recognizing differential signaling as all but essential for sending multigigahertz signals across pc boards and backplanes, you shouldn't be surprised at the proliferation of ultrawideband, active,.....(design idea added 9/03)

Electromagnetic field detector (mitedu) - This circuit is sensitive to low frequency electromagnetic radiation and will detect for example hidden wiring or the field that encompasses a transformer. Pickup is by a radial type inductor, used as a probe which responds well to low frequency changing magnetic and electric fields. Ordinary headphones are used to for detection. The field that surrounds a transformer is heard as a50 or 60Hz buzz. (added 5/02)

Electromagnetic field detector (tomi.geo) - This lovely circuit is a real gem! Easy to assemble and more sensitive than many commercial devices available. It's based around an LF351 low-noise operational amplifier and a 1mF choke acting as the sensor. Unlike most other simple EMF detectors, this one has a meter output for accurate reading, but alternatively, you can also roughly....(added 10/05)

Electromagnetic Field Detector (zen22142) - This circuit is sensitive to low frequency electromagnetic radiation and will detect for example hidden wiring or the field that encompasses a transformer. Pickup is by a radial type inductor, used as a probe which responds well to low frequency changing magnetic and electric fields. Ordinary headphones are used to for detection. The field that surrounds a transformer is heard as a50 or 60Hz buzz. (added 5/02)

Electromagnetic Field Probe with Meter Output - This tester is designed to locate stray electromagnetic (EM) fields. It will easily detect both audio and RF signals up to frequencies of around 100 kHz. Note, however that this circuit is NOT a metal detector, but ...(electronic design added 6/07)

EMF Probe with Meter - An electromagnetic field probe designed to detect changing electric and magnetic fields. The probe has a meter output and headphone socket as well.
....(electronic design added 9/02)

High impedance FET probe extends RF spectrum analyzer's usable range - 07/21/05 EDN-Design Ideas: Diodes and guard traces suppress high-voltage static-discharge transients.....(design idea added 8/05)

IC & DMM form direct read out temperature probe - 09/01/06 EDN-Design Ideas: Simple circuit yields linear voltage-versus-temperature output.....(design ideadadded 05/06/07)

Isolated Probe - This probe allows connecting to such 'floating' circuits to a normal scope input. As seen in the circuit, it is based on using an optocoupler. The one shown in the diagram is a dual unit, but I had a pile of them here, so thats what I used. ….(design added 08/08))

Light Receiver works from 1kHz to over 70mhz - This circuit uses one tiny C-MOS inverter IC to form a modulated light receiver with a very fast response. It is designed around a PIN photo diode that is packaged for use with plastic optical fibers. It can be used as an optical fiber receiver. By using the open end of the optical fiber it can "sniff" out any modulated light signals. ….(designed by David A. Johnson)

Logic Chip Tester - (electronic Circuit diagram added 03/03/03)

Logic probe - (schematic / circuit added 2/07)

Logic Probe (Andy Collinson) - This logic probe uses a single CMOS IC and shows three logic conditions, High, Low and Pulsing. In addition if the probe input is neither hi or low (the high impedance state of tri-output logic ic's) then no LED's will light. Power from the logic probe is taken from the logic circui.....(electronic circuit added 7/03)

Logic Probe (Jose Pino) - An useful and easy to build Logic Probe with Pulse injector. An schematic of a "digital version" is included.

Logic Probe MkIIB - Essential for servicing all types of Digital circuits ….(diagram added 05/07)

Logic Probe uses Bicolor LED - 03/13/98 EDN-Design Ideas: 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.....(design idea added 03/03/03)

Logic Probe with Pulse - (Tony van Roon's electronic schematic / circuit added 4/02)

Logic Probe with Pulse CMOS - (Tony van Roon's schematic added 8/03)

Logic Probe3 Audible TTL/CMOS - (Tony van Roon's circuit added 9/04)

LOPIC Logic Probe with Pulser - (circuit added 9/04)

LTD-Low Cost Telemetering Device - (circuit added 6/07)

Magnetic field probe requires few components - 12/15/06 EDN-Design Ideas: (design idea added 05/06/07) Hall-effect sensor and DMM explore stray fields.

Make a simple PC based frequency meter - 04/29/99 EDN-Design Ideas: A simple, low cost, and precision frequency meter uses only two pins of a pc parallel port (Figure 1). The TTL-level periodic input signal with frequency fIN connects to the ACK pin of LPT1. This input produces an IRQ7 hardware interrupt on every rising edge (Figure 2). The software counts the number of IRQ7 interrupts in the time unit.....(design idea added 11/05)

Making Differential Probes - For sensing audio signal voltages across devices that are not ground referenced (added 6/06)

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.....(design idea added 3/03)

Oscilloscope Probing of PC133/Rambus Circuits - Pericom Semiconductor Application Note # 021 (app note added 2/05)

PIC16C72 PicmasterR Emulator Probe for PIC12C67x Emulation. - Microchip Application Note Published 27-Mar-98 (app note added 6/06)

Precision Wideband Current Probe for LCD Backlight Measurement - DN101 Design Notes (Linear Technology) (app note added 1/06)

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 provides an 800-psec pulse having rise.....(design idea added 05/02)

Pulse Reading Logic Probe solorb - (circuit / schematic design added 6/06)

RF Probe - Use this probe with any transmitter for tuning. Connect the probe at the output of each stage and tune till maximum DC voltage appear on Digital Voltmeter. (added 11/05)

Scope Probe Measures High Frequencies - 01/18/96 EDN-Design Ideas: Measuring clocks and critical signals accurately is often inconvenient. Normal 10× 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.....(design idea added 09/05)

Simple Logic Probe uses Bicolor LED - 03/13/98 EDN-Design Ideas: 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.....(design idea added 03/03/03)

Simple RF Probe - Indispensable for any RF work. Uses just 4 passive components (added 6/07)

Triangle Squarewave Generator - (design added 8/03)

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. (electronic design added 6/07)

Ultra-simple Voltage Probe - Detects 1.8 to 220 Volts DC or AC. Minimum parts counting. (electronic circuit added 06/07/08)