I'm trying to prepare to teach some basic Ohm's law concepts, applications, and diagnostics for automotive technicians. We work with a nominal 12 volt system, I might use a regulated 10 volt bench supply to simplify calculations.
I wanted to use a resistance decade box so I could manipulate circuit resistance very precisely at will, like this one:
https://www.amazon.com/Extech-38040...4779996&sr=8-4&keywords=resistance+decade+box
looks like a clone of this one:
https://www.amazon.com/REED-Instrum...4779996&sr=8-7&keywords=resistance+decade+box
but it looks like the box is rated at .3 or .5 watts and I think I would toast that in short order. 12 volts, 1 ohm resistor = 1 amp. 1amp * 12 volts = 12watts. Correct me if I'm not calculating my power requirement right.
I will need to load my circuit with at least 5 amps, like a powerful headlamp bulb. That would be about 60 watts, and because of the initially low resistance there would be a high in-rush current, so to speak.
I want to add linear resistors to the circuit without burning them up. I might need to incorporate a circuit breaker to prevent excessive current flow in case circuit is assembled incorrectly as well.
Any advice on spec and availability of suitable components?
Thanks
I wanted to use a resistance decade box so I could manipulate circuit resistance very precisely at will, like this one:
https://www.amazon.com/Extech-38040...4779996&sr=8-4&keywords=resistance+decade+box
looks like a clone of this one:
https://www.amazon.com/REED-Instrum...4779996&sr=8-7&keywords=resistance+decade+box
but it looks like the box is rated at .3 or .5 watts and I think I would toast that in short order. 12 volts, 1 ohm resistor = 1 amp. 1amp * 12 volts = 12watts. Correct me if I'm not calculating my power requirement right.
I will need to load my circuit with at least 5 amps, like a powerful headlamp bulb. That would be about 60 watts, and because of the initially low resistance there would be a high in-rush current, so to speak.
I want to add linear resistors to the circuit without burning them up. I might need to incorporate a circuit breaker to prevent excessive current flow in case circuit is assembled incorrectly as well.
Any advice on spec and availability of suitable components?
Thanks