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

Thread Starter

HermanB

Joined Apr 18, 2016
7
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?
 

MrChips

Joined Oct 2, 2009
19,724
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.
 

Thread Starter

HermanB

Joined Apr 18, 2016
7
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.
 

Thread Starter

HermanB

Joined Apr 18, 2016
7
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!
 
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