# Linear opto isolator circuits

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 based. It can be used many ways. For example ; separate the circuit from the power line, send audio signal, Electronic medical, etc.

How it works
The resistance of the separation is very 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.

Figure 1 the Linear opto isolator circuits

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

Firstly, the input voltage will be changed into current. As circuit that show in Figure 1 , it include 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 amplifier will be 200 ohms.

The external amplifier is connected 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.

If the total gain too low, we need to use the transistor for working look like the 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 ICs
T1_____BF256___FET
C1,C2_____1uF 50V ___Ceramic capacitors
R1________1M___1/4W Resistors tolerance: 5%
R2________100 ohms _________”__________