SSR question

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Thread Starter


Joined Feb 24, 2007
I am working with some sensory equipment, mainly programming and RS232 wiring (12v).
I intend to use a SSR that has a 12V input to close a 5v circuit.

Sadly I seem to have hit a snagg , I am not the best person with electronics and I have not used relays much.

The problem is I have an OPTO22 DC60S5 SSR, and it has 4 pins on each side,+1 , 2 and 4 ,3+.
Now I assumed if I delivered 12V to 4 and 3+ , it would switch +1 and 2 on.

Thing is +1 and 2 seems tp be closed before I even apply 12V...???

I was told a resistor was not needed as the relay has 1000ohm resistor inside it,,,do I have to calculate the amps??

Why is 1 and 2 connected?

Anyone have any ideas as to what I am doing wrong??


Joined Apr 20, 2004
If 1 & 2 are ohmically connected with no control voltage applied, it might be that the SSR is shorted.

SSR's, by the way, are eminently suited for AC voltage switching. With DC, though, you only get one turn-on, as they latch on for as long as the DC is applied to the load terminals.

Try a P & B T92 series relay. But it's always a good idea to have some idea of the current you are going to switch. That way, you can select the right-sized components. If, for instance, your 5 volts is in the 200 milliamp region, a small reed relay would work just fine.


Joined Jun 30, 2006
The DC control voltage range is 3–32 VDC contacts 3 and 4
Switched contacts 1 and 2 will read infinite ohms even if there is a control voltage.

Since that's a DC device and has polarity markings I do recommend following those markings.

I despise the 'datasheet'. The data is layed out incompetently.
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