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Edit:

I’ve just learned that a 500mA PSU is not going to necessarily output 500mA; it’s not a constant current PSU. It CAN output that much, but only if its components are asking for that much. It changes nothing about the total current of the circuit.

Original post:

I am experimenting with a TEC-12706 unit. I know that it draws 1.98 Ohms, and ideally it would take 12V and 5 or 6A. I have two wall outlet PSUs: both 12V, one 100mA and one 500mA.

Problem is, I don’t know how to calculate the resistance or current if I am already providing a specified current to my circuit; I’ve only worked with 9V batteries before.

If I’m using a 12V 500mA PSU and a 1.98 Ohm TEC, how do I calculate the current in the circuit?

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    \$\begingroup\$ R = U / I ⇒ I = U / R \$\endgroup\$
    – Zac67
    Feb 27, 2022 at 4:58

2 Answers 2

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The resistance and current are already specified, there is nothing to calculate.

The power supplies can't provide the required 6A so the result is indeterminate - either the power supply shuts down, provides only little current, or gets a blown fuse or other damage.

So don't connect them.

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That unit takes 6 amps at 12 volts. If you try to run it off of a 500 mA supply it will either not do very much, or it will overload the supply, depending on if the supply has over-current protection or not.

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