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I apologize in advance if this is simple. I've only had an intro to circuits class and all we did was analyze existing circuits, and even that's been a while.

For a design project I'm trying to wire together (theoretically, not in practice) 4 thermoelectric plates (15.4V DC and 1.7 ohms each), 2 computer fans (12V DC and 0.15A each), and 2 door lock motors (12V DC and 2.6A each). To clarify, I don't actually have to do this. I just have to prove that it's possible and show the set-up to make it possible. Ideally, I'd like to wire it all up with a/some AC to DC converters so that everything can run off of a 120V AC wall outlet.

I've done some initial analysis and found the following requirements for a few set-ups:

2x motors in parallel: 12V/5.2A
2x motors in series: 24V/2.6A

2x fans in parallel: 12V/0.3A
2x fans in series: 24V/0.15A

4x Thermoelectric plates in series: 61.608V/9.06A
4x Thermoelectric plates in parallel: 15.4V/36A
2x Thermoelectric plates in parallel then series: 30.8V/18.12A
2x Thermoelectric plates in series then parallel: 30.8V/18.12A

What's got me confused is how to wire everything together since they have different voltages, amperages, or both. I apologize if this is simple, but as a mechanical engineering major, I have almost zero experience or knowledge about anything more than simple circuit analysis.

Any assistance that can be provided would be greatly appreciated.

John North
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1 Answers1

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You shouldn't connect the motors in series, because the current each motor will require will depend on its mechanical load much more than on its rated current.

Likewise, the fans shouldn't be connected in series. So you need 12 volts at 5.5 amps for the motors and fans.

I assume the "thermoelectric plates" are resistive heaters - if so, they should work on 12 volts, but won't get quite as hot. It appears that they need 9 amps each at 15.4 volts.

Peter Bennett
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