Guys, I have a question about how the galvanic isolation between a direct current signal can be performed, as an example of a 0-10Vdc signal. An alternating current signal, as little knowledge in electronics, I think we can use a 1:1 transformer and a digital signal we could use an optocoupler, but what are the options when we have a voltage or direct current signal
Can you be more specific about the nature of the DC signal?
If it is on/off, use an optocoupler. If variable voltage or current, it can be converted to a digital signal, in which case the required resolution has to be specified.
The old fashioned solution, was to convert the voltage to a frequency, and pass that through a transformer. Now you can digitize it and use opto isolation.
As an example, make the isolation between a voltage signal that varies from 0 to 10 vdc
You can run an opto isolator in analog mode. But it won't be perfectly linear, you have to compensate. Mainly, the LED side because it's a diode and has a non-linear V-I curve. Thus the voltage up to the LEDs Vf will be a "dead band".
One approach for a slowly changing DC voltage is to use a voltage to frequency converter IC, followed by an optocoupler.
I take it you have not had time to think about the required resolution.
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Is this how these isolator converters work?
You can use a pair of (matched) optocouplers with photodiode outputs. They will compensate for non linearities and temperature, to a degree. Depends on how accurate you need.
I used this too many years ago and I'll have to think how the circuit works. I believe the input diode was current fed and the receiving diode was in the feedback loop of an amplifier. I'll have to look to see if I can find it.
This reference uses a twin output photo diode to provide the "matching " function.
Like you I had this problem a little while back (maybe 40 years). As far as I remember the best solution at the time was to use a pair of optocouplers and negative feedback to linearise the loop.
Today I'd go with V-F & F-V conversion. A quick google didnt come up with a ready built solution
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