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Please note, this is not a shopping question; this is a what type of component works best for this scenario question.

I have an induction heater circuit and a 5A max. / 24V wall wart, and I'd like to switch off / on the output of the wall wart so that I can control the power output of the induction heater.

About 7 years ago I found something by the name of SSR or SCR (or something) on digikey and that cost a reasonable amount (< 10 USD), and now I can't find it any longer. The SSR's on there that can handle that much power cost around 50 USD, which is too much to design with. The frequency can be low (5-100 Hz) range, since it is a relatively slow heating process.

I plan to switch the relay on/off with a raspberry pi, and will probably need a transistor in between. I don't want a mechanical relay since the thing will probably break before even making real use of the product.

The component I found prior was upright flat-rectangular with 4 thru-hole terminals coming out of the bottom smaller side. I found some that look like that but like I said they were in the 50 USD range. Also, that component if I recall correctly was for switching on/off AC for a different type of heater, so maybe that's why it was cheaper?

What types of alternative components should I be considering based upon these requirements?

Daniel Donnelly
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2 Answers2

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SSR or Solid State Relay is what you are after. You should be able to trigger this one right off the 3 volt rpi gpio. FOTEK SSR-40DA. Here is a DC one CPC1709J. Use a voltage divider or zener diode so you dont exceed the 1.2v input. You will likely need a heat sink.

You may want to consider using a mosfet instead and running higher frequency. Higher frequency means you will transfer more power for a given coil size. Also reliability and efficiency will likely be higher than an SSR pushed to 100Hz.

This one switches low side (which is safe in your 24v application), but it is nice because it triggers right off of the 3 volt rpi gpio without a driver.RFD3055LE 60V 11A N-Channel Mosfet

Here is a really nice mosfet wiring tutorial. bildr.org mosfet tutorial

ericnutsch
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If you want to use an SSR, you'll need to get one designed for switching DC. Like this one Unlike mechanical relays which can switch AC or DC, SSR's are designed for switching either AC or DC loads.

DLS3141
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