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schematic

simulate this circuit – Schematic created using CircuitLab

I'm thinking to use a MOSFET solid state relay triggered by a MCU to trigger a micro magnetic relay.

I will be using a sufficiently rated flyback diode at the magnetic relay.

This doesn't seem to be commonly done. My reason is that high current solid state relays are way more costly than a low current SSR and a micro magnetic relay together.

Is there any reason to not do this?

EDIT - added schematic

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  • \$\begingroup\$ If it's not commonly done then probably there's a better (simpler, cheaper) way. Draw a schematic of your proposal so that we really see what you mean. \$\endgroup\$ – Bimpelrekkie Aug 16 '17 at 13:58
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    \$\begingroup\$ Why do you need a Solid State Relay to turn on a micro magnetic relay? Are you building a Rube Goldberg? \$\endgroup\$ – Curd Aug 16 '17 at 14:24
  • \$\begingroup\$ building a what?... \$\endgroup\$ – LsD Aug 16 '17 at 14:31
  • \$\begingroup\$ The magnetic relay coil draws too much current for the MCU output to control it directly. \$\endgroup\$ – LsD Aug 16 '17 at 14:32
  • \$\begingroup\$ Why the trouble of an SSR? Why not just a MOSFET to turn on the coil for the relay? \$\endgroup\$ – winny Aug 16 '17 at 14:45
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This circuit is fine: -

enter image description here

Choose a MOSFET that has a low enough gate-source threshold voltage to ensure that at the logic drive voltage, the MOSFET adequately turns on.

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