Gotcha. So, when you run resistors together, no matter whether the are in a series or parallel, you just add up the value of each individual resistor to get a total value of the rated Watts. I know the resistance is changed when you run them in a series vs parallel; I'm pretty sure I get that one. It's just the watts that I'm curious about now.

 

Exactly!!!! you add the individual power capacity of each resistor, independent of series or parallel.

 

Great info!! Thank you for the help.

 

I'd be careful of adding wattage (in a parallel circuit) unless the resistance is the same between two resistors. Never add wattage in series. The proper way of calculating the power dissipated by any resistor is to find the current going through that resistor. Ohms law - E = IR. E = the voltage dropped across the resistor (just put your volt meter leads across the resistor), I = the current through the resistor (current meter in series with the resistor), R = resistance in Ohms. Power dissipated - P = EI. Soooo, you can substitute, P = R x I squared or P = E squared divided by R.

 

I guess you missed the point that all of the resistors were 470 ohms. And you can add the total power capacity of resistors in series due to separate voltage drops across them, and the same current flowing....

 

This series/parallel circuit will dissipate a total of 2 watts (at max current), but I was giving out the formula's to prevent someone new to electronics from treating this as a golden rule.

 

The circuit is good for 2 watts. In a series circuit the current flow is the same in every resistor. You will just need to add up each value of the resistors in the circuit to get the total resistance. The wattage does not change just the total resistance. With a 12 volt circuit with a 12 ohm resistor you will have 1 amp of current and use 12 watts of power being used at the resistor. If you add a second 12 ohm rsistor in series with the first you have 24 ohms. You would then have 1/2 amp current flow and 6 watts of power being used at each resistor. You will have 6 volts drop across each resistor and 3 watts. If you double the voltage to 24 volts you are back to one amp current but you will now have 12 volts dropped across each resistor and 24 watts total with 12 watts at each resistor. The total watts in a series ciruit do add up from the ammount that is being used in each resistor but as you add them the current goes down with a constant voltage so the total wattage goes down. To get the total wattage you wooould have to raise the applied voltage. If you put the 2 resistors in parallel the resistance would be 6 ohms total. If you apply the same 12 volts you would have 2 amps in the circuit with one amp flowing through each resistor and a total of 24 watts. Each resistor is using 12 watts. The circuit you have drawn will work. Its been too long since I have had to stop and think about this, good foor for thought.

 

I appreciate the input. I'm glad to know that my time hasn't gone to waste, as I've already soldered everything together. Now, I just have to hope that those carbon film resistors will stand up to the heat and vibration of the engine compartment in the Vee of the engine.