It would be convenient for me to make a battery pack for a 3W thermal wire stripper so I could use it when not near an outlet. But it needs AC (i suspect, internally,
The amount of power I need is very small - I know I could use a full sized inverter with battery pack, but that is bigger and bulkier than would be ideal. I have this feeling that there is probably a smaller, lighter, cheaper way to get this, knowing that the actual power I need is so small. You know, one of those el-cheap modules from china like the $2 dc-dc converters, rated for only very low power - anyone seen anything like that, and/or know what search terms to use in ebay to find that, as opposed to the countless inverters advertising hundreds of watts of output power?
It seems like actually making one myself would be a real pain, so if there isn't either an easy trick to making one myself that I don't know, or an off the shelf cheaply made in china module, I should just use a commercial inverter with builtin small battery.
If I were making one I'd get an old mains transformer with a split secondary and run it backwards. Probably try a pair of cross coupled NPN BJTs to drive the transformer. It would require some experimentation to get the right output and it probably wouldn't be very clean. Might result in a few dead transistors while experimenting...
Any reason to not want to simply buy a battery powered hot wire stripper? I know they're not exactly cheap but it seems the easy solution.
Small inverters do exist, like this 120W model and this 100W model. Both 12V powered, designed for use in cars, and I do assume they're also available in 110V versions. My quick search didn't turn up anything even lower power.
I'm pretty sure a plastic "ground" would be illegal here in the U.S. But that's just for AC power safety and it's only there in case something goes wrong.
Have you ever actually tried that? In THEORY it would work but I BELIEVE the secondary resistance/impedance is too low and you'll "short-out" the low-voltage power supply.
...When I was a "kid" I MIGHT have tried running a transformer backwards to step-up from 120V to 1200V. (That's a MUCH worse idea than what you're proposing.) I can't remember if I tried it and fried a transformer, or if I was just thinking about it, or maybe someone just warned me not to try.
DVDdoug:
...When I was a "kid" I MIGHT have tried running a transformer backwards to step-up from 120V to 1200V. (That's a MUCH worse idea than what you're proposing.)
Is that in response to me? To clarify, I don't mean running it backwards off mains, I mean driving the low voltage side with a pair of transistors from a low voltage DC supply. I know it works, I've done it.
As for connecting the mains to a transformer the wrong way round, the much younger me can confirm that if you touch wires carrying mains on to the secondary connections you get a big flash and blow the fuse. I learnt something that day.
DrAzzy:
It would be convenient for me to make a battery pack for a 3W thermal wire stripper so I could use it when not near an outlet. But it needs AC (i suspect, internally,
But you may well be completely wrong, as it may just have a heater element (seems quite likely in fact). Heaters run on DC just as well as AC.
Please provide links to all hardware you refer to in a question, we cannot guess these details reliably.
Is that in response to me? To clarify, I don't mean running it backwards off mains, I mean driving the low voltage side with a pair of transistors from a low voltage DC supply. I know it works, I've done it.
Yeah, I screwed-up the quote. :-*
I know you weren't proposing running 120VAC into the "secondary" but I'm just not sure if it will work at all "backwards" because of the low resistance/impedance.
I know you weren't proposing running 120VAC into the "secondary" but I'm just not sure if it will work at all "backwards" because of the low resistance/impedance.
Works perfectly well. This is an example of if you are not sure then build it and see what happens. Maybe it will go up in smoke, maybe it will sit there doing nothing, maybe it will do what you want. Any which way you learn something, and isn't that the point of this hobby?