Test & Measurement Circuits

Audio Circuits, Test & Measurement Circuits

Audio oscillator circuit

ICL 8038 waveform generator. ICL8038 is a monolithic waveform generator IC that can produce sine, square and triangular waveforms with very little distortion. The frequency can be programmed from 0.001Hz to 300 KHz using external timing capacitor and resistor. Frequency modulation and sweeping can be attained by using an external voltage. Other features of the […]

Test & Measurement Circuits

Simple function generator circuit

LM1458 Simple Function Generator. A simple function generator circuit using LM1458 is known here. LM1458 is a dual general purpose operational amplifier. The two opamps inside LM1458 has a common bias network, power supply line and are independent of each other in operation. The LM1458 does not require an external frequency compensation circuit and has

Industrial Circuits, Test & Measurement Circuits

Digital thermometer circuit

Digital thermometer circuit. CA3162, CA3161 & LM35. A simple digital thermometer circuit with out a micro controller and having a seven segment LED read out is shown here. The circuit is based on three ICs: CA3162, CA3161 and LM35. CA3162 is a monolithic analogue to digital (A/D) converter that has BCD output. The A/D converter

Test & Measurement Circuits

Capacitance meter using LM2917

Description. The circuit diagram of a simple capacitance meter using IC LM2917 is shown here. The LM2917 is a high gain monolithic frequency to voltage converter IC from National Semiconductors. Even though the main application of LM2917 is in tachometers, it can be also used for a variety of applications like this. Capacitance values from

Conversion Circuits, Test & Measurement Circuits

Frequency to voltage converter using LM331

Making a frequency to voltage converter – All you need to know Description LM331 is basically a precision voltage to frequency converter from National Semiconductors. The IC has a hand full of applications like analog to digital conversion, long term integration, voltage to frequency conversion, frequency to voltage conversion. Wide dynamic range and excellent linearity

Test & Measurement Circuits

LED based transistor tester

Description. Here is the circuit of a very simple transistor tester which used two LEDs for displaying the condition of a transistor. Both PNP as well as NPN transistors can be tested using this circuit. Quad 2 input CMOS NAND gate IC CD4011B is the heart of the circuit. Out of the four NAND gates

Test & Measurement Circuits

Digital voltmeter using ICL7107

Description. The circuit given here is of a very useful and accurate digital voltmeter with LED display using the ICL7107 from Intersil. The ICL7107 is a high performance, low power, 3.5 digit analog to digital converter. The IC includes internal circuitry for seven segment decoders, display drivers, reference voltage source and a clock. The power

Automotive Circuits, Test & Measurement Circuits

F to V Converter

F to V Converter Circuit using LM555 Timer Description. Here is a very simple circuit diagram of a frequency to voltage (F to V) converter. Such a circuit finds numerous applications in projects like digital frequency meters, tachometers etc. The circuit is mainly based on a LM555 timer IC. The IC is wired in mono

Test & Measurement Circuits

Sensitive electromagnetic field sensor.

Description. This is the circuit diagram of a very sensitive electromagnetic field sensor which can sense electromagnetic field from 40Hz to 140Hz. The low noise opamp LF351 and associated components forms the pick-up section. 1uH coil L1 is used for sensing the field and the IC1 performs the necessary amplification. If the picked electromagnetic field

Test & Measurement Circuits

Peak detector circuit using LM393

Description. This is the circuit diagram of a very simple and cheap peak detector circuit. This circuit operates from 5V DC and can detect signals up to 150 KHz. Dual comparator IC LM393 is the heart of this circuit. First comparator IC1a is used for detecting the peak of the input signal. Second comparator IC1b

Test & Measurement Circuits

How to test a relay

This article shows you how to test a relay. A relay will usually have a coil, pole terminal and a set of contacts. The set of contacts that are open when the relay is not energized are called normally open (N/O) contacts and the set of contacts that are closed when the relay is not

Test & Measurement Circuits

Wind meter

Description. Here is a very simple wind meter (anemometer) circuit. I can’t guarantee much on the accuracy of this circuit but it circuit works quite fine. You can measure wind speeds up to 75m/s using this circuit. The transistors Q1 and Q2 are used for sensing the wind. The relationship between thermal impedance of the

Test & Measurement Circuits

Zener diode tester

Description. Here is a very simple circuit that can be used for testing Zener diodes. The IC1 NE555 is wired as an astable multivibrator and the output of the IC is stepped up to a high voltage AC using the transformer T1.The unloaded AC voltage will be around 120V. The AC voltage is rectified by

Test & Measurement Circuits

Transistor tester circuit

This article discusses various circuits that can be used to test a Transistor, both NPN and PNP. We have structured this article into two circuits. If you have any doubts about any section please ask through comments. 1. Transistor Tester built using Transistors 2. Simple Transistor Tester (Contains both Circuit Diagram and PCB Lay Out)

Test & Measurement Circuits

Quartz crystal tester circuit

Description. This a very simple and inexpensive circuit that can be used to test quartz crystals.Here a Colpitts oscillator is wired used the transistor T1.When the crystal is connected between terminals A and B the circuit will produce high frequency oscillation.The oscillations will be generated only if the crystal is a good one.The diode OA91

Test & Measurement Circuits

High impedance DC voltmeter.

Description. A high impedance DC voltmeter using a uA741 IC is shown here. The operational amplifier is used as a non-inverting DC amplifier in which the negative feedback is through a DC meter requiring 1mA for full scale deflection. Since R6 is 100 Ohms, the meter will show full scale reading when the DC input

Audio Circuits, Test & Measurement Circuits

Audio clipping indicator circuit

Description. This circuit can be used to identify whether there is a clipping in a particular wave form. Clipping is a phenomenon in which the amplitude of a particular waveform drops before it reaches the expected limit. This circuit glows an LED as an indication if the signal under test has clipping. The circuit is

Audio Circuits, Test & Measurement Circuits

Signal tracer circuit.

Description. A high gain amplifier circuit that can be operated from a battery pack of 6 or 9 volt battery pack is shown here.The IC1 uA 741 is wired as a high gain non-inverting amplifier and its output is amplified by a pair of complementary transistors (Q1 & Q2) to drive the speaker.The negative feedback

Signal Conditioners, Test & Measurement Circuits

Schmitt trigger circuit using IC uA 741

Description. A Schmitt trigger circuit shows two distinct signal input levels for turning the circuit ON and OFF. The difference between the Von and Voff voltages called hysteresis Schmitt triggers are useful in converting slowly rising waveforms into fast rising ones and in relay like application. The circuit shown here uses a 741 with positive

Test & Measurement Circuits

Micro ampere meter circuit using uA 741

Description. The micro ampere meter shown here is basically a DC millivolt meter.The circuit gives full scale deflection for 0.1V input.The current to be measured is passed through a known resistance R and the voltage drop across it is measured.Here the IC 1 uA 741 op-amp is wired as a non inverting amplifier. Circuit diagram

Test & Measurement Circuits

Voltage follower circuit

Description. An AC coupled unity gain  gain voltage follower operating on a single supply is shown here.The voltage divider network of R1 and R2 provides a DC voltage equal to half the supply voltage to the non-inverting input of the 741.The output DC voltage therefore stands at half the supply voltage.The output signal swings above

Test & Measurement Circuits

555 Tester circuit

Description. NE555 is an IC which is widely used in timers and control circuits. A circuit for independent testing this IC is given here. Here the NE555 is wired as an astable multivibrator. When the push button switch S1 is pressed the LEDs D1 & D2 will flash alternatively. That is when output is high

Audio Circuits, Test & Measurement Circuits

Sound pressure meter

Description. Here is a simple circuit that can be used to check the sound levels.The sound pressure meter is vey useful in setting up home theater systems , if you need to test the sound pressure of each channels on different positions in the room. The circuit is nothing but a non- inverting amplifier based

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