My problem is that I have about 170 volts as source, and need to drop it to about 140 V, while the load will draw near 1 amp. Is a voltage divider practical at these values?

 

A thread belongs to the TS (Thread Starter). Now you have your own thread.

Your thread has been split off from here:

http://forum.allaboutcircuits.com/threads/confused-circuit-math-with-resistors-and-voltage.123158/

 

So you need to drop 30V @1A = 30W

Apply Ohm's Law I=V/R
Power = I x V

Hence you will need a 30Ω resistor rated for more than 30W, i.e. about 50-100W
Think of a 30v, 30W light bulb.
That is how hot it is going to get.

Three 12v 15W light bulbs in series will do it.

If this is mains AC, use a step-down transformer.

 

A thread belongs to the TS (Thread Starter). Now you have your own thread.

Your thread has been split off from here:

http://forum.allaboutcircuits.com/threads/confused-circuit-math-with-resistors-and-voltage.123158/

So sorry. Did not mean to, it is all about not quite knowing how it all works. Is there a tutorial somewhere about using the forum?

 

So you need to drop 30V @1A = 30W

Apply Ohm's Law I=V/R
Power = I x V

Hence you will need a 30Ω resistor rated for more than 30W, i.e. about 50-100W
Think of a 30v, 30W light bulb.
That is how hot it is going to get.

Three 12v 15W light bulbs in series will do it.

If this is mains AC, use a step-down transformer.

 

Thanks again. This goes a long way towards solving the issue, now practical trials will have to ensue. My theoretical knowledge is a bit limited/rusted, being an old-timer!