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I'm looking for relay boards that can handle 20V/20A DC easily and can be switched with the raspberry pi. I have been googling for days but haven't found anything ready made for DC, only for AC. I want to turn on a cheap tire inflator (12V and 12Amps) with the pi and the power for the inflator comes from a power adaptor. The relays I have found are mostly found in cars and I'm not experienced enough to come up with my own solution as these types of relays require more than 5V to be switched. Can you help or provide a diagram?

simplex123
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  • Have you considered buying two relays, one controlled by the Pi and another controlled by the first relay? It might be hard to find a 20amp module directly controllable by the Pi. – joan Jan 20 '17 at 16:20
  • I have not considered this. Doesn't this add a lot of complexity to the project? – simplex123 Jan 20 '17 at 16:22

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I can't imagine why you'd have to 'Google for days', but I don't think Google is the best way to find a relay with a particular set of specifications. I'd suggest you use the screens and filters available on the websites of some of the big electronic distributors. I'd probably try Mouser first.

For example, I took some of the specifications in your question, input them to Mouser's web search engine, and got the following list of candidate relays. This one may meet your specifications.

You will note that this relay can not be driven directly from your RPi GPIO pin. You will need a transistor in between your RPi and the relay coil to make this work; i.e. you will drive the transistor directly from the RPi GPIO, and switch the relay coil with the transistor. This is not difficult, and this is the approach I'd take if it were my project. Following is a schematic from another answer that you may find useful:

schematic

simulate this circuit – Schematic created using CircuitLab

However, if you don't want to use a transistor to interface your RPi to the relay, you may be able to locate a Solid State Relay. Mouser's website can help you find SSR's also.

If you decide to use a transistor to interface your RPi to an electro-mechanical relay, please edit your question to reflect that & we'll help further.

Seamus
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if you want to high current capacity Relay for control device you can use Solid state relay

refer this link for SSR Solid State Relay

Kalarav Parmar
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Use an N-chsnnel MOSFET to switch a 12V (car) relay. A 2N7000 is good for this.

user400344
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