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how do i use a transistor to connect to an AC transformer?i want to use DC to run an AC transformer?

i wanna know if its possible to use a transistor to power up a transformer(like from cellphone chargers)?Could sum1 help me?

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jeff-o8 years ago
What is your goal, to step up a DC voltage? Or to control the output voltage from the transformer? You're going to need a lot more than just a transistor in either case.
joinaqd (author)  jeff-o8 years ago
ok my goal is to use DC electricity to run an AC transformer(like from cellphone chargers).i opened a disposable camera once and saw it it uses a transistor to run the small 300volt transformer.as you already know,transformers cannot work with DC electricity,so i need a way to convert to AC so i can run the transformer....
jeff-o joinaqd8 years ago
Ah, I see. The transistor was probably part of an oscillator circuit (either resistor-capacitor or inductor-capacitor). The DC from the battery was converted to AC (or at least a close approximation) using low voltage discrete components, then stepped up using the transformer. That's not the only way to do it, but it is quick & dirty and very inexpensive. You can do the same thing using a 555 timer if you like.
joinaqd (author)  jeff-o8 years ago
ya correct...but do you know how i could wire up the transistor to the transformer so it works like the disposable camera transformer?i checked out Plasmana's instructable SMALLEST ELECTRIC SHOCKER, but the transformer he uses has 5 contacts, and my one has 4 contacts(the one from cell phone charger).i also checked out the JOULE THIEF instructables and it was a bit confusing how they wired up the transistor..PLUS they dont have any schematic so i cant do it. i'd be grateful if u know how and also please put in a schematic...
jeff-o joinaqd8 years ago
Hmmm, that 5th pin is something called a center tap, and to use Plasmana's schematic you'll need one like that. Also realize that the transformer you have may not even have the right winding ratio (in fact, I'm almost certain it won't), so it would probably be better to set it aside and get yourself a few disposable camera bodies.
I have a small transformer out of something and it only has four pins but it was used for creating high voltage for a neon tube (I think it was a neon tube) but I want to drive it with a transistor rather then a 55 timer. Would it still be possible to do this.
Sure, but you still need to feed the transistor an AC signal (or something close!)
OK, thanks, I will try that. (also my other comment should say 555 timer)
joinaqd (author)  jeff-o8 years ago
(>_<) i was hoping there was a way to do it, but no...anyway dude,thanks for taking your time to answer me. mostly no1 bothers to answer my questions.only 2 people did,u and randofo..
jeff-o joinaqd8 years ago
No problem! Don't feel too bad though, Instructables "Answers" is pretty new and I'm sure there are lots of people around who haven't tried it out yet.
jtobako8 years ago
There are inverters that take a car's DC power and convert it to house AC power. If you are looking for schematics, you would have to know what loads and parts you are going to use.
randofo8 years ago
You want a solid state relay like this one. When you apply a DC voltage it will open and close a separate AC circuit.

You simply take a two wire extension cord and cut one of the two wires in half. Attach each side of the AC wire to one of the AC terminals on the AC side of the relay. Insulate this very well so you don't electrocute yourself. Then, plug in your AC transformer into the extension cord. When voltage is supplied to the DC side, power will flow through the extension cord to your plug.

To better control the AC side, you can attach your low-voltage DC control signal (like a transistor).

I have used this particular relay before and burnt out two before I realized it requires a little bit extra resistance. In other words, stick a resistor (100 - 200 ohms) onto the input or output pin of the DC side in series with your controller. Not all solid state relays will require this, but the one I linked to does (and adding a little extra resistance would be a good habit to get into).