# How to reduce 170V to 140V @1A?

Discussion in 'General Electronics Chat' started by HermanB, Apr 19, 2016.

1. ### HermanB Thread Starter New Member

Apr 18, 2016
7
0
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?

Oct 2, 2009
12,643
3,457
3. ### MrChips Moderator

Oct 2, 2009
12,643
3,457
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.

Apr 18, 2016
7
0

Apr 18, 2016
7
0

6. ### HermanB Thread Starter New Member

Apr 18, 2016
7
0
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!