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I need to create a circuit that I can use an Arduino to control a 400~500 DC voltage source. I am not used to opto-isolators, but I was thinking about using it to separate both systems. But I cant seem to find one that can handle 500V DC in the Vcc port. My thought process(I am not sure how to create and opto-isolator, so assume the LED and transistor in the middle are the opto-isolator): If you guys know a better way to completely separate both systems please give me your input. BTW the current is very low, below 1mA.

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ R2 looks a bit low to me. \$\endgroup\$
    – user16324
    Oct 28, 2014 at 0:17
  • \$\begingroup\$ I am sorry: the resistors values are just random for now. I just need some input on the opto-coupler, or a way to separate the circuits. \$\endgroup\$ Oct 28, 2014 at 0:20
  • \$\begingroup\$ An opto-isolator does consist of an LED and a transistor (or sometimes a more complex circuit). The first thing you have to do is to determine how the 500 volt source is controlled - I suspect that the controlling device does not actually have to switch 500 volts, but until we know tha actual control circuit, I don't think we can make any useful suggestions. Also - is the control only on/off, or do you need to adjust the voltage as well? \$\endgroup\$ Oct 28, 2014 at 0:21
  • \$\begingroup\$ The 500v comes from a high voltage power supply. So you just set the voltage and click the on button(that simple). The arduino side is only an on/off. \$\endgroup\$ Oct 28, 2014 at 0:24
  • \$\begingroup\$ To safely and reliably interface with this supply, we need to know the voltage and current that the "On/Off" button switches. \$\endgroup\$ Oct 28, 2014 at 1:09

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If response times in the ms are acceptable, you could use an optically coupled pair of back-to-back MOSFETs such as the CPC1393GRTR.

enter image description here

This particular one can switch 600V at up to 90mA, with maximum on/off times of 5ms and maximum 'off' leakage of 1uA. It would typically drop less than 100mV at a few mA.

Isolation voltage input-to-output is 5000V claimed, you'll have to evaluate if that's safe enough for your application.

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  • \$\begingroup\$ Can I ask you what would the circuit look like? I am not familiar with Solid State Relays. \$\endgroup\$ Oct 28, 2014 at 3:40
  • \$\begingroup\$ And this seems to be exactly what I need looking at the data sheet. ms would work just fine. Can you please help me with the circuit? Thank you very much. \$\endgroup\$ Oct 28, 2014 at 3:57
  • \$\begingroup\$ @ThiagoOmena have you even bothered looking online for opto-isolator example circuits? they are very straight forward. Just make sure you read the max current rating for the LED for it's resistor. \$\endgroup\$
    – KyranF
    Oct 28, 2014 at 9:21
  • \$\begingroup\$ I have but I never seen a Dual MOSFET opto isolator. Better ask and be safe than sorry. 500v DC can do a lot of damage. I looked for circuits for this specific opto but I couldn't find any circuits. \$\endgroup\$ Oct 28, 2014 at 19:14
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    \$\begingroup\$ Thanks guys. I had to switch the opto because it was hard to find, but thanks for helping me understand how this works. It worked out perfectly. \$\endgroup\$ Nov 4, 2014 at 4:13

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