Many electronics circuits and projects for learning in simple ways.

Linear opto isolator circuit

This is the linear opto isolator circuits that use a few parts and cheap. In circuit we use the opto compiler ICs number of MOC 5010 as a base. It can use it in many ways. For example, separate the circuit from the power line, send an audio signal, Electronic medical, etc.

Working of Linear opto isolator circuit

The resistance of the separation is very high so makes the MOC5010 is used to the circuit connector in-house. For example: the television receiver that the width of the frequency band from 5 Hz to 100KHz, So can connect audio signal very high.

Linear opto isolator circuit
Figure1: Linear opto isolator circuit

The working of MOC 5010, it will change current that move at input into the voltage as ratio of the input current.

Firstly, the input voltage will be changed into a current. As circuit that shows in Figure 1. It includes of gain is 0.75 and maximum input of circuit is have 2 Vrms, and the wide frequency band of 118 KHz at -3 dB.

The Mosfet -T1 change voltage to current, the Slope about 3-4 mA per voltage, and the idle current at drain-source lead about 10 mA.

The amplifier A is the transmission of resistance about 200 mV per mA. Thus gain of the circuit will be 0.6 to 0.8 (-4.5 to -20 dB). The maximum output impedance of the amplifier is about 200 ohms.

The external amplifier connects to pin 4 of ICs. When the input voltage is higher than 2 Vrms. So should use the variable resistors that connect as the divider circuit as Figure 2.

Variable resistors that connect as the divider-circuit
Variable resistors that connect as the divider-circuit

If the total gain too low, we need to use the transistor for working look like FET. The importance of this circuit is to use a separate power supply. As well as the OV, it must be separated.

The parts you will need.
IC1:  MOC 5010, the opto compiler IC
T1: BF256___FET
C1,C2: 1uF 50V, Ceramic capacitors
0.25W Resistors tolerance: 5%
R1: 1M
R2: 100 ohms

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