Archive for the ‘Test & Measurement Circuits’ Category

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 ICL8038 are high linearity, high level outputs, simultaneous sine, square, triangle wave outputs, low external parts count, high temperature stability etc. The working of ICL8038 is as follows. The external timing capacitor (C2 in the circuit diagram) is charged and discharged using two internal current…

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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 built in short circuit protection. Lm 1458 has a wide supply voltage range and it is available in 8 pin mini DIP package. Description. Four opamps (2 from each IC) is used in the function generator circuit. First opamp IC 1a is wired as an…

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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 inside the IC is a dual slope type with differential inputs. The IC has an internal timing circuitry and hold function. When the hold function is enables, the output IC latches itself to the present state. CA3161 is a monolithic BCD to seven segment converter IC….

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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 0.01uF to 0.1uF can be measured using this circuit. The capacitance to be measured is connected between pin 2 of the IC and ground. The output voltage available across resistor R2 will be proportional to the Cx and it will be displayed by the meter….

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Frequency to voltage converter using LM331

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 makes the IC well suitable for the applications mentioned above. Here the LM331 is wired as a frequency to voltage converter which converts the input frequency into a proportional voltage which is extremely linear to the input frequency. The frequency to voltage conversion is attained by differentiating the input frequency using capacitor C3 and resistor R7 and…

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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 inside the IC, only three are used here and they are used as NOT gates by shorting their input terminals. Gates U1a, U1b, resistor R1 and capacitor C1 forms a square wave oscillator. The frequency of this oscillator can be adjusted by using R1. The…

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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 dissipation is less than 10mW and the display stability is very high. The working of this electronic circuit is very simple. The voltage to be measured is converted into a digital equivalent by the ADC inside the IC and then this digital equivalent is decoded…

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F to V Converter

F to V Converter Circuit using LM555 Timer CircuitsToday.com has introduced an online store to buy books that provide the basics and applications of 555 timer IC. There are 3 books in store. You can buy them after reading our reviews. You can know more by clicking here:- 3 Great Books to Learn 555 Timer Circuits and Projects 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…

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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 is in the audio frequency range, it can be heard through the head phone Z1.There is also a meter arrangement for accurate measuring of the signal strength. Transistor Q1 performs additional amplification on the picked signal in order to drive the meter. Circuit diagram. Notes….

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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 is wired as a buffer to increase the current gain. Circuit diagram. Notes. The circuit can be assembled on a Vero board. The IC must be mounted on a holder. Use 5V DC for powering the circuit. The input AC voltage should not exceed 10V…

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