Using Opto-isolator or optical coupler

Thread Starter

yiudavid

Joined May 1, 2009
5
Hi everyone..

i would like to ask one thing:

i have one detecting device which has output as soon as it is activated.
The output is a buzzer and a sound will be given (0.5V).
Now i wanna modify it to from audible to visible by replacing LEDs on it.

i wanna using this output to light up one or more LEDs.
Some people say i can use Opto-isolator or optical coupler to boost up the voltage.

How can i find a suitable Opto-isolator or optical coupler?
and
What specific thing i need to concern?

thank you very much!!
 
Last edited:

t_n_k

Joined Mar 6, 2009
5,455
Opto-couplers/isolators are primarily intended for controlling a circuit condition where galvanic isolation of one part of a circuit from another is required or convenient.

They can be used to provide a low-high power control - although you'll need more than 0.5V ??? to drive the input side isolating LED in the opto-coupler. You'll also need a power source on the higher power output side to provide the power for controlling or driving the output side device(s).

You need to be more specific about your application and what your 0.5V source relates to.
 

Thread Starter

yiudavid

Joined May 1, 2009
5
Thanks replying!!

i want to claify it
One detecting device will have output as soon as it is activated.
The output is a buzzer and a sound will be given (0.5V).
Now i wanna modify it to from audible to visible by replacing LEDs on it.

please help me!
 

bertus

Joined Apr 5, 2008
21,850
hello,

Do you have a schematic of the circuit with the buzzer?
May the buzzer be removed?

Greetings,
Bertus
 

Thread Starter

yiudavid

Joined May 1, 2009
5
i haven't removed...but i tend to do it.
can i simply removed it and using LEDs to check whether it can light or not?
 

bertus

Joined Apr 5, 2008
21,850
Hello,

Remove the buzzer and measure the voltage.
The voltage may be higher than with the buzzer.
Report the voltage back so we can see what actions to take.

Greetings,
Bertus
 

Thread Starter

yiudavid

Joined May 1, 2009
5
i have removed the buzzer and test again.
it is 3V for the output.

but i have search several opto-coupler's datasheets
most of their operating forward voltage are 1~1.7 V
may i need to step down the voltage first, but how ?
 

bertus

Joined Apr 5, 2008
21,850
Hello,

The voltage is enough to drive a led.
You will need to put a resistor in series with the led of the optocoupler to limit the current through the led.
The current needed is dependend on the type of optocoupler you want to use.

Greetings,
Bertus
 
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