Solid state switching

I am getting further on my retrofit,

I need 8 SSR's that will handle a 24vdc 150mA inductive load. Paying $31 a piece for the Crydom SSR's seems overkill

Do you guys have any other solutions ? I have been thinking about finding a MOSFET that will do the trick and build the boards and add the additional circuitry to make it work correctly.

Thanks!

Jake wrote:

I am getting further on my retrofit,

I need 8 SSR's that will handle a 24vdc 150mA inductive load. Paying $31 a piece for the Crydom SSR's seems overkill

Do you guys have any other solutions ? I have been thinking about finding a MOSFET that will do the trick and build the boards and add the additional circuitry to make it work correctly.

Thanks!

You could use my relatively cheap DC SSRs and add a small NPN power transistor externally to amplify the current. This would make it an opto-Darlington circuit. I don't think any additional components would be needed.

Jon

That was one path I was looking into. I thought with the inductive loads I would need a flywheel diode around the load to dissipate the back emf. Even that way it should be a $2 for a diode and a transistor. Still half the price of the SSR's. It would be nice to have everything on one board!

I have a drawing in the attachments, this is what I came up with.

2amp darlington, 60 volts NPN

General purpose diode 100v 4 amp surge current 0.3a forward current

What do yall think?

www.automationdirect.com/adc/Shopping/Ca...)/AD-SSR6M12-DC-200D

About half the price of the crydom ssr, still $17:(. They are good for up to 12 amps so they could be repurposed in the future.

Jake wrote:

I have a drawing in the attachments, this is what I came up with.

2amp darlington, 60 volts NPN

General purpose diode 100v 4 amp surge current 0.3a forward current

What do yall think?

That would work, but it is not isolated.

Jon

Here's a circuit that will boost the current from my little DC SSRs. it uses a 2N2222A, which should be good for several hundred mA up to 24 V or so. It also shows the freewheel diode to safely control the inductive effect of the relay coil.

Jon