31-07-2015, 07:43 PM
According to an article an IRF740 with a few components should do the variable job but it won't be regulated, there's a bit about it here:
http://www.eleccircuit.com/the-variable-...ly-0-300v/
I wouldn't have though a small ripple would affect much.
Just for something to do I did a quick calc for a 4 volt heater at 1 amp running via a 20 ohm 50 watt pot divider across a 6.3 volt AC source, at first glance the pot derating seemed to fit ok but maybe someone else can check to make sure just in case I got it the wrong way round.
Lawrence
http://www.eleccircuit.com/the-variable-...ly-0-300v/
I wouldn't have though a small ripple would affect much.
Just for something to do I did a quick calc for a 4 volt heater at 1 amp running via a 20 ohm 50 watt pot divider across a 6.3 volt AC source, at first glance the pot derating seemed to fit ok but maybe someone else can check to make sure just in case I got it the wrong way round.
Lawrence
