Rewinding solenoid

[humphrey]

I want to change a solenoid from 6v to 12v.
What does this entail?

[Station X]

It might be easier to connect a resistor in series with it.

If you go down the rewind route you'll need to keep the number of ampere turns the same. For the same power at 12V you'll need half the current, so twice the number of turns. DC resistance will need to double.

[Herald1360]

Is it AC or DC operated? DC- just a resistor same as existing coil resistance. For AC a bit more complkicated- you'll need to find a resistor which will limit the current to the same as that taken when fed by 6V which won't be anything like the same as the coil resistance- probably quite a bit higher.

[kalee20]

Originally Posted by Station X

For the same power at 12V you'll need half the current, so twice the number of turns. DC resistance will need to double.

Erm... DC resistance will quadruple!

You need the same ampere turns. With half the current, double the voltage, resistance increases 4 times. You get that by using a wire 0.707x the diameter of the original wire (ie half the cross-section area) and wind twice as many turns, which will fit in the same original space.

[humphrey]

Thanks for the info. I think I am ready to go now. The resistance would have been too great with the original, that is why I want to rewind.

[Station X]

Originally Posted by kalee20

Erm... DC resistance will quadruple!

Correct.

[AC/HL]

To further complicate, is it for continuous operation? If it's just a pulse you may get away with it.

[Herald1360]

Originally Posted by humphrey

The resistance would have been too great with the original, that is why I want to rewind.

Did you mean convert from 12v to 6v?

How could the original resistance of a 6v solenoid be too high for 12v drive?

[ex 2 Base]

I think some one has miss read your request. IF the coil winding is not potted, then it might be possible to rewind the coil with a smaller CSA wire with many more turns. I cannot remember the theory regarding resistance and cross sectional area, I should but can't, its not a straight ratio. I have done the very same thing in the pasT. If the current is large perhaps a solenoid from a car might be the answer. Perhaps Ed might know, he's up on winding. Ted

[Station X]

I cannot remember the theory regarding resistance and cross sectional area.

For a given material the resistance is directly proportional to the length and inversely proportional to the CSA. So twice the length and half the CSA gives four times the resistance.