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The TLP222AF can handle AC or DC. The 60 volt rating is more than enough for a 24V circuit. I would keep the current under 200 mA to keep the heat down. 200 mA is not a limiting factor as the coil current of a small signal relay is usually under 50 mA.
They are packaged in a 4 pin DIP like the typical opto coupler and cost only a bit more, $1.09 from Digi-Key.
The MOSFET SSRs can handle more current and voltage than the typical optocoupler and eliminate the need for an intermediate driver. For low power they're equivalent to a relay contact.Ah, that makes sense. I wanted the relays to swing both ways for future expansion purposes too.
If your circuit didn't use both an NO and NC contact they could have replaced the relays too.
Here is a simpler version of the output.
These MOSFET solid state relays can drive your relays directly. Max rating is 60V, 500mA although I would only use them at about half that. By the way, they can also switch AC.
There is a resistor in series with the inputs to set the current.
Indicator LEDs run on 24 VDC as do the relays. I drew them as 24 VDC since that's the supply in your diagram. The circuit could be used for 12 VDC if you prefer.
Diodes across the relays to catch the turn off spike that might harm the MOSFETS.
Big thoughts that I vaguely understand and had to read up on a bit to figure out.
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