TESTERS and METERS cisrcuits
Audio MilliVoltmeter
The meter presented here has a very wide frequency range, and uses a switched attenuator for range adjustment. The attenuator uses the 30-10-3 sequence, which provides 10dB steps between ranges.
3 Channel Spectrum Analyzer
-This3 channel15 LED spectrum analyzer can be used as an addition to any audio amp project. It produces fantastic displays on3-LED bars that can be individually adjusted for any particular frequency range.
Pink Noise Generator for Audio Testing
For audio testing, a pink noise source is an invaluable tool. It is essentially a flat frequency response noise source, and will quickly show any anomolies in speaker systems, room acoustics and crossover networks.
Self Oscillating Amplifier for Distortion Testing
allows the home constructor to make quite accurate measurements, without having to spend a lot of money on a low distortion oscillator
-As a piece of test equipment, an audio oscillator has to be considered essential for anyone working in with hi-fi gear.
Most circuits use bypass capacitors and can deliver substandard performance if the capacitors have poor pulse characteristics. Few if any articles cover how to test bypass capacitors for pulse characteristics. The circuit in Figure 1 tests these characteristics.
-The Femto Capacitance Meter measures in the low femtofarad area having a resolution of 10 femtofarads (fF). The meter has six ranges allowing a maximum measurement of 4 microfarads.
-Design Ideas / It's often necessary to know the acidity of a solution to control a process. Even inexpensive pH meters can be relatively costly, and many of the inexpensive models have no output that you can readily connect to a computer interface. A simple solution to this problem is to attach a pH probe to a high-impedance input of an op amp and read the output with a digital voltmeter
-The circuit tracer in Figure 1 is a handy tool for finding connectivity paths on a pc board. Because the sense voltage you use to measure the path is lower than a transistor's VBE voltage, you can use the design in circuits containing semiconductor elements without affecting the measurement. The tracer's output takes the form of audio tones
-There are a number of ways to measure distortion, none of which is perfect. Probably the best is a spectrum analyser, which shows the individual harmonics and their amplitudes. These are too expensive for the likes of you and me (well, me, anyway) and the next best thing is featured here.
Zener Diode Tester
-Using a single 555 Timer IC and a small transformer to generate a high voltage, this circuit will test zener diodes of voltage ratings up to 50VDC. The 555 timer is used in the astable mode, the output at pin3 drives a small audio transformer such as the LT700.
Phantom Power Battery Test Circuit
this instrument will light if the battery voltage is over 42V
OpAmp Design & Test Board
Opamps are wonderful little building blocks, but quickly building a test circuit is a real pain. This board is for testing ideas using OpAmp
Electromagnetic Field 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.
Versatile Zener Diode Tester
The circuit of a versatile zener diode tester presented here enables you to verify the specified breakdown
voltage and tolerance values.
Light Pollution Meter
LED brightness control circuit and a multimeter to compare light levels to LED level.
LED Audio VU Meter
This project is also an essential part of the expandable analyser to be published soon and one meter circuit is used for each frequency band. There are many other uses for a simple LED VU meter. They are ideal as power meters on amplifiers, can be used with mixers
VU Meter
5 led VU meter, in PDF format, includes circuit board,
Transmission line tests 1 kW device using only 100W
A 13.56-MHz, ISM (industrial, scientific, and medical)-band RF-measurement device had the test requirement of a 50-hour, 1-kW burn-in. The device under test needed to be simultaneously stressed at an RF potential and RF current equivalent to 1 kW, but the only spare RF source at hand was a 100W RF generator
Simple Square Wave Oscillator
-A very basic square wave generator using a CMOS 4011 NAND gate.
Logic Probe
-A single CMOS 4011 IC makes this handy logic probe. Displays high, low and pulsing outputs.
Function Generator
-A function generator using the ICL8038 integrated circuit. Is has four ranges and capable of sine, square and triangle outputs.
MilliGauss Meter by Rev Tomas Scarborough
-The circuit provides an easy yet reliable way to detect the intensity of a.c. (or e.l.f.) fields around the home or workplace. It is doubly effective because it does not merely detect the electromagnetic radiation emitted by electrical appliances, but the electromagnetic energy actually absorbed by the body.
Transistor tester fits into your pocket
It can be helpful to rapidly and easily determine the polarity (npn or pnp) and function of a transistor. The pocket-transistor tester is ideal for quickly testing without regard to such parameters as gain and frequency response. You connect the transistor, or device under test, between the collectors, T, of an astable multivibrator.
Transistor Spot Checker
The simple transistor spot checker is one of the most handy gadgets on the experimenter's workbench, especially if said experimenter has numerous surplus transistors with unknown histories or mysterious "in-house" part numbers.
Multi Wire Cable Tester
A multi wire cable tester with a separate LED for each wire. Will show open circuits, short circuits, reversals, earth faults, continuity and all with four IC's. Designed initially for my intercom, but can be used with alarm wiring, CAT 5 cables and more.
Connection Tester
-A low resistance ( 0.25 - 4 ohm) continuity tester for checking soldered joints and connections.
Sine Wave Generator
-A classic Wien Bridge oscillator using an Op-Amp covering a frequency range of 15 to 150kHz in four switched steps.
Two Crystal Test Circuits
Two simple test circuits to check operation of quartz crystals.
Bench Amplifier
A small 325mW amplifier with a voltage gain of 200 that can be used as a bench amplifier, signal tracer or used to amplify the output from personal radios, etc.
Simple emulator speeds testing
Designing and testing embedded hardware can be frustrating if you have to rely on somebody else's perhaps-unready firmware to test your hardware. Often, hardware is ready for testing before debugging and system firm-ware are available from software developers.
Simple tester checks LCDs
The circuit is a simple configuration to test the performance of an LCD. The circuit produces biphase square waves with negligible dc content.
Telephone Test Circuit
this type of circuit is for quick testing of telephone equipment.
Signal Injector and Tracer
A simple test circuit to fault find audio and radio equipment. Can be used to inject a square wave signal, rich in harmonics, or used with headphones as an audio tracer.
Beat Balance Metal Detector by Rev Thomas Scarborough
A Beat Balance Metal Detector made from discrete components.
Coil Coupled Operation Metal Detector by Rev Thomas Scarborough
-A Coil Coupled Operation Metal Detector made from readily obtainable components and using an ordinary medium receiver as a detector.
Off Line Telephone Tester
Here is a circuit of an off-line Telephone tester which does not require any Telephone line for testing a Telephone instrument. The circuit is so simple that it can be easily assembled even by a novice having very little knowledge of electronics.
Low Frequency Oscillator
-A low frequency test oscillator for testing tone controls and experimenting.
EMF Probe Version 2
-An electromagnetic field probe designed to detect changing electric and magnetic fields. The probe has switchable gain, a frequency response up to 400kHz and independent audio and meter monitoring.
Infrared Remote Control Tester
Here’s a simple, low-cost, and easyto- construct infrared remote control tester. The tester is built around
an easily available infrared receiver module
Full Featured Transistor Tester
The design featured here provides the ability to test the Gain at various collector currents up to 5A Breakdown voltage
ESR Meter
Digital / Standard Phone Line Tester
make sure that the line is suitable for modem use and your PCMCIA does not damage if you plug it in
Femto Capacitance Meter
This meter measures into the low femtofarad area. Measuring in the femto area allows the smallest capacitors to be measured with precision.
Frequency & Capacitance Meter
Infrared Remote Control Tester 2
A simple IR receiver to facilitate in testing of Infra Red Remote Control handsets.