Electronic Circuits and Diagram-Electronics Projects and Design

Current amplifier and buffers. Buffer amplifier. Buffer amplifier is a circuit which transforms electrical impedance from one circuit to another.  The main purpose of a buffer is to prevent the loading of a preceding circuit by the succeeding one. For example, a sensor may have the capability to produce a voltage or current corresponding to a particular physical quantity it sense but it may not have the power to drive circuitry it is connected to. In such situations a buffer can be used. A buffer when connected between the sensor and the succeeding circuitry easily drives the circuitry in terms…

Transimpedance amplifier / current to voltage converter. The transimpedance amplifier is a circuit that converts current to a proportional voltage. It is also termed as current to voltage converter or simple I to V converter. The transimpedance amplifier has ideally zero input resistance and low output resistance. The transconductance amplifier has a lot of applications in day to day electronics. For example, converting to current detected by a photo diode into a proportional voltage, digital to analog converter (DAC) applications etc. Current to voltage converters are of two types, passive and active. Passive current to voltage converter. As the name…

Differential amplifier. Differential amplifier is a closed loop amplifier circuit which amplifies the difference between two signals. Such a circuit is very useful in instrumentation systems. Differential amplifiers have high common mode rejection ratio (CMRR) and high input impedance. Differential amplifiers can be made using one opamp or two opamps. Both of these configurations are explained here. Differential amplifier using one opamp. The circuit diagram of a differential amplifier using one opamp is shown below. R1 and R2 are the input resistors, Rf is the feedback resistor and RL is the load resistor. Derivation for voltage gain. Equation for the…

Voltage comparator circuit. Voltage comparator is a circuit which compares two voltages and switches the output to either high or low state depending upon which voltage is higher. A voltage comparator based on opamp is shown here. Fig1 shows a voltage comparator in inverting mode and Fig shows a voltage comparator in non inverting mode. Non inverting comparator. In non inverting comparator the reference voltage is applied to the inverting input and the voltage to be compared is applied to the non inverting input. Whenever the voltage to be compared (Vin) goes above the reference voltage , the output of…

Summing amplifier using opamp. Summing amplifier is a type operational amplifier circuit which can be used to sum signals. The sum of the input signal is amplified by a certain factor and made available at the output .Any number of input signal can be summed using an opamp. The circuit shown below is a three input summing amplifier in the inverting mode. In the circuit, the input signals Va,Vb,Vc are applied to the inverting input of the opamp through input resistors Ra,Rb,Rc. Any number of input signals can be applied to the inverting input in the above manner. Rf is…

Instrumentation amplifier using opamp. Instrumentation amplifier is a kind of differential amplifier with additional input buffer stages. The addition of input buffer stages makes it easy to match (impedance matching) the amplifier with the preceding stage. Instrumentation are commonly used in industrial test and measurement application. The instrumentation amplifier also has some useful features like low offset voltage, high CMRR (Common mode rejection ratio), high input resistance, high gain etc. The circuit diagram of a typical instrumentation amplifier using opamp is shown below. In the circuit diagram, opamps labelled A1 and A2 are the input buffers. Anyway the gain of…

Opamp inverting amplifier. An inverting amplifier using opamp is a type of amplifier using opamp where the output waveform will be phase opposite to the input waveform. The input waveform will be amplifier by the factor Av (voltage gain of the amplifier) in magnitude and its phase will be inverted. In the inverting amplifier circuit the signal to be amplified is applied to the inverting input of the opamp through the input resistance R1. Rf is the feedback resistor. Rf and Rin together determines the gain of the amplifier. Inverting operational amplifier gain can be expressed using the equation Av…

Integrator circuit. An integrator circuit is a circuit in which the input waveform. An integrator circuit based on opamp is shown in fig1. Such a circuit is also termed as an integrating amplifier. The circuit is somewhat similar to an opamp inverting amplifier but the feedback resistor Rf is replaced by a capacitor Cf. The circuit diagram of an opamp as an integrator is shown below. Opamp integrator circuit diagram. Equation for the instantaneous output voltage of the opamp integrator can be derived as follows. Applying Kirchoff’s current (KCL) at node V2 we get i1= iF + iB Since the…

Sample and hold circuit using op-amp As the name indicates , a sample and hold circuit is a circuit which samples an input signal and holds onto its last sampled value until the input is sampled again. Sample and hold circuits are commonly used in analogue to digital converts, communication circuits, PWM circuits etc. The circuit shown below is of a sample and hold circuit based on uA 741 opamp , n-channel E MOSFET BS170 and few passive components. Description As the name indicates , a sample and hold circuit is a circuit which samples an input signal and holds…

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 hysteris Schmitt triggers are useful in conbverting slowly rising waveforms into fast rising ones and in relay like application. The circuit shown here uses a 741 with positive feedback via R5,R6 and R7 for fast switching.Voltage dividers R8 and r9 set the DC input voltage to the non-inverting input terminal to half the supply voltage.The amount of positive feedback depends on the ratio of R6 and r7.the larger the ratio,the smaller will be the…