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I have a vacuum gauge with on board relays that trip at set pressures. They have a rating of 30 VDC, 1 A. The solenoid valve I need to control is 50 VDC with max current 3A (also is inductive load of course).

What is my easiest, cheapest option here to still use the vacuum gauge relay to control the solenoid? It seems like I need the relay to complete the circuit of an amplifier input that can provide the current and power drawn by the solenoid. I just need to figure this out fast, any help in the right direction in terms of products is appreciated.

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What is my easiest, cheapest option here to still use the vacuum gauge relay to control the solenoid?

The simplest solution might be to find a 2nd relay that can handle the solenoid voltage and current and, activate it with a 12 (or 24) volt supply using the current 30 volt contact. Don't forget to put a flyback diode across the relay coil and the solenoid though.

Alternatively, you could choose an N-channel MOSFET rated for about 60 volts or higher and capable of handling 3 amps or more. You'll still need a flyback diode across the solenoid and, you'll still need an auxiliary supply to drive the gate but this time it should be limited to 12 volts in case you damage the MOSFET gate-source region: -

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    \$\begingroup\$ okay, I like these ideas, should be easy to throw together. Thanks! \$\endgroup\$ – mccragre0001 Jul 9 '20 at 17:11

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