Amplifier Circuit Diagramsvoltage converterZener Diode

Voltage-Controlled Current Source Schematic Circuit Diagram

Voltage-to-Current Conversion with TL084 Op-Amp Circuit

The designed source, utilizing the Type TL084 quadruple opamp, serves the purpose of converting an input signal within the range of 0–5 V into a corresponding current spanning 0–20 mA. The TL084 Quad Op-Amp is specifically engineered as a low-power, high-impedance JFET input quad operational amplifier, suitable for operation from either a single or split supply. This circuit configuration finds practical application in scenarios like transferring measurands (quantities being measured) over extended leads. The inclusion of lead resistance within the current loop is inconsequential, ensuring that it does not impact the measurement.

Operational Amplifiers and Their Roles

An operational amplifier is an integrated circuit designed to amplify weak electrical signals. It comprises two input pins and one output pin, with its primary function being the amplification and output of the voltage difference between the two input pins. Opamp IC1a functions as a straightforward input amplifier. While Opamp IC1b adjusts the direct voltage component of the amplified input signal. The operating point can be shifted using P2, allowing for customization. For instance, it is feasible to configure an output current of 4 mA for an input voltage of 0 V, resulting in an output current range spanning 4–20 mA.

Voltage-controlled current source Schematic diagram

Signal Amplification and Voltage-to-Current Conversion

Opamps IC1 and T1 collaborate to transform the output of IC1b into a 15 V signal. This setup enables IC1d and T2 to operate effectively as voltage-to-current converters. The resultant output current traverses through the load resistance RL and can be customized by adjusting the values of R2 and P1 to meet specific amplification requirements. Additionally, the circuit’s functionality extends to serving as a temperature-to-current converter by configuring the input potential divider with a fixed resistance and one possessing a negative temperature coefficient.

Temperature Compensation for Zener Diodes in Precision Applications

In situations demanding precision, both Zener diodes should undergo temperature compensation. Zener diodes, specialized rectifying diodes capable of withstanding breakdown due to reverse breakdown voltage without complete failure, play a critical role in this setup. This section will delve into the concept of utilizing diodes for regulating voltage drop and the reverse-bias mode operation of Zener diodes, elucidating their role in voltage regulation within a circuit.


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