Amplifying Small Signal With Solid State Relay
Here is a mosfer driver version, I added a zener to limit Vgs to about 15v since the input can range up to 20v which is usually the max Vgs spec and can damage the mosfet (check yous mosfet specs, you may need to use a lower zener value).







simulate this circuit &ndash; Schematic created using CircuitLab

Vgs can be as low as 5v so you should select the output mosfet accordingly so that it can turn on with a low Rds-on at that voltage. A logic level mosfet should do.



If a low side switch is an option you can use the following







simulate this circuit

The load supply can be as high as the mosfet can take as a max Vds