Multimeter Shunt
The current range in multimeters, particularly the more inexpensive ones, is restricted by the load limits of the internal...
5-Range Linear-Scale Ohmmeter
Rx is inserted in the feedback path of IC1. A known reference current is selected from reference voltage gene...
Low-Ohms Adapter
The circuit consists of a 5-V regulator, constant-current source Dl, D2, and Ql, and op amp gain stage Ul. Power is provid...
Digital Led Voltmeter
The voltage to be measured is digitized in an analog-to-digital (A/D) converter and then displayed in three decimal d...
Synchronous System
The circuit uses a synchronous-detection scheme to measure low-level resistances. Other low-resis-tance-measuring circui...
Capacitor Esr Measurer
The equivalent series resistance (ESR) of a capacitor can be measured using this circuit and an ac voltmeter. Ul fun...
Digital Tachometer Counter
This circuit produces a readout for the digital tachometer circuit. IC9 is a 3-digit LED display driver, counter...
Digital Vom Phase Meter
The phase-angle meter will work with either analog or digital inputs. A DVM is used as a readout device. The output...
Microfarad Counter
This circuit measures capacitance by the time it takes an unknown capacitor to reach 6.32 V (10 V 63% or 1RC time const...
Simple Diode Curve Tracer
Suitable for matching diodes or examining VII characteristics of two terminal devices (diodes, etc.), this circui...
B-Field Measurer
This circuit develops an output voltage that is proportional to the magnetic induction, B, flowing through its probe"s coi...
Meter Tester
This unit uses switches and resistors to provide a number of current ranges. It allows you to test most of the meters availabl...
Sensitive Swr Meter
Using a toroidal pickup coil around the center conductor of a coaxial cable, this circuit can be used to measure the SW...
Four-Trace Oscilloscope Adapter
This simple adapter uses an oscillator (567) to drive a counter (U2) and switch (U3) that selects the outpu...
Magnetic Field Meter
Using a pickup coil to drive an amplifier (IC3A-B-C-D), this meter circuit can be directly calibrated in field-intensi...
Simple Capacitor Tester
An LM3909 LED flasher is used as an oscillator, and the capacitor connected to the terminals determines frequency. ...
Duty-Cycle Measurer
An Intersil 7101 31/2-digit A/D converter is used to display the duty cycle of a pulse train as a percentage. The frequ...
Oscilloscope Preamp
In many oscilloscopes, the most sensitive range is 2 to 5 mV, although it is often possible to improve this to 1 to 2 m...
Ac/Dc Indicator
By using two switching transistors and two LEDs, this circuit can distinguish low-level ac and dc signals. If the red LED i...
Frequency-Ratio Monitoring Circuit
This circuit produces an output frequency that is linearly proportional to the ratio of two input freque...