• 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.

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  (added 2/06)

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 / (added 3/03) 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, .....

Electromagnetic field detector:  (electronic design added 11/06)

Electromagnetic Field Detector:  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 #3:  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 estimate the frequency of the field by plugging in headphones. It can detect any field from 50Hz to 100kHz, making it highly versatile and a worthwhile addition to any hobbyist's workbench. (added 10/05)

High impedance FET probe extends RF Spectrum analyzer's usable range:  02/05/2004  EDN-Design Ideas  In low-noise analog circuits, a high-gain amplifier serves at the input to increase the SNR. The input signal level determines the input-stage gain; low-level signals require the highest gain. It is also standard practice in low-noise analog-signal processing to make the circuit's bandwidth as narrow as possible to pass only the useful input-signal spectrum. (added 10/05)

Logic Probe #1:  (electronic (schematic / circuit added 4/02)

Logic Probe #2:  with probe (added 4/02)

Logic Probe #3:  with probe, CMOS (added 5/05)

Logic Probe #5:  (circuit added 9/04)

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

Logic Probe with Pulse:  (circuit / schematic added 6/05)

Logic Probe with Pulse CMOS:  (circuit / schematic added 6/05)

Logic Probe(3) Audible TTL/CMOS:  (circuit added 9/04)

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

Make a simple PC based frequency meter:  04/29/99 EDN-Design Ideas / (added 11/05) 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 of timebase T. If this timebase is 1 sec, the frequency of the input signal equals the number of IRQ7 interrupts in 1 sec....

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

Modified Scope Probe Tests SurfaceMount Assemblies:  09/25/97 EDN-Design Ideas / (added 3/03)  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 in Figure 1 makes it easy to probe such assemblies and obtain reliable measurements. The technique works with most oscilloscope probes. Remove the probe cap, exposing the probe tip and ground "collar." Cut a 4-in. piece of 30-AWG, single-strand, Kynar-insulated wire (the type that engineering labs almost universally use to make jumper modifications)....

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

Precision Audio Frequency Peak Detection Probe :  for use with a digital voltmeter (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 / (added 05/02) 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 and fall times shorter than250 psec. The pulses amplitude is10V, and the circuits source impedance is50 Ohm.....

Pulse Reading Logic Probe #2:  (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 / (added 09/05) 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 power supply or other special setup. Unless ground leads are short (10 to 20 mm), these leads introduce considerable distortion to most probes.

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

This Technical Brief Describes How to Use the PIC16C72 Picmaster(R) Emulator Probe for PIC12C67x Emulation.:  Microchip Application Note Published 27-Mar-98   (app note added 6/06)

Triangle and Squarewave Generator:  (design added 8/03)

TTL Pulse Reading Logic Probe:  (circuit / schematic design added 6/06)

Ultra-simple Voltage probe:  (electronic circuit added 4/05)