Opto-isolator Help ><"

[Kming]

Anyways i know the basis of an opto-isolator, like how it works and stuff... But im having trouble understanding how to wire it up..

Will the output of the optoisolator be the same as the input?? or do we need another volt supply??

 

[cobra1]

the output of the opto isolator will require its own power source, think of it in terms of a transistor, the input would be equivalent of base input, and the power then flows through the emitter - collector

heres a circuit to help you

**broken link removed**

 

[Kming]

So in the circuit that you used as an example, Basically the 12V will power the circuit on the right, and the transistor will i guess will "superimpose" the signal from the laptop battery to the 12v circuit?

or am i miss interpreting .. ><"

 

[cobra1]

hi, the drawing i posted uses the opto isolator outputs to trigger a transistor that then allows power to flow across the relay energising it.

it is done like this as the opto isolator can only handle small currents and is used to trigger another device, either a transistor or a triac etc. This transistor or triac will then handle the full load of the device being powered.

 

[Kming]

Hey cobra1, thanks for the help so far,

But as you might know, i posted another thread regarding trying to control an ignition coil through the use of a function generator.. And since i wanted to use an opto-isolator, i posted this thread,

And Now Using your example diagram i tried to redesign a circuit, and i was wondering if you could tell me whether or not it can work at all.

The L1/Inductor symbol represents where the transformer would go.
and the transistor i planned on using is the 2n3055,

Thanks for the help so far

 

[cobra1]

HIYA

it would help if i knew what it was doing, what does this run?? an engine, if so what type etc

 

[Kming]

Ok Sorry for the lack of an explaination..

simply put, i'm making a circuit to control an ignition driver, through the use of a function generator, where i want to protect the function generator from the high voltage of the transformer.

V2 is used to represent the function generator in the schematic.
V3 is the external supply
L1 is the transformer..

 

[ljcox]

Hey cobra1, thanks for the help so far,

But as you might know, i posted another thread regarding trying to control an ignition coil through the use of a function generator.. And since i wanted to use an opto-isolator, i posted this thread,

And Now Using your example diagram i tried to redesign a circuit, and i was wondering if you could tell me whether or not it can work at all.

The L1/Inductor symbol represents where the transformer would go.
and the transistor i planned on using is the 2n3055,

Thanks for the help so far

Your circuit needs 2 additional components.

1. A diode across L1 to limit the back EMF otherwise it is likely to destroy the transistor.
2. A resistor from the base to gnd to bypass the Icbo & the Opto dark current.

 

[Kming]

Your circuit needs 2 additional components.

1. A diode across L1 to limit the back EMF otherwise it is likely to destroy the transistor.
2. A resistor from the base to gnd to bypass the Icob & the Opto dark current.

You mean the base of the transistor 2n3055 or To the base of the transistor in the opto??

 

[ljcox]

The base of the 2N3055 since this base will otherwise have to pass the dark current and its own Icbo