Power supply

I've looked up a bunch of power supply designs on google and other places. I'm currently using the normal design of mains->transformer->rectifier->caps and voltage regulator 7805.

The problem with this setup is the transformer takes up a ton of space. I'm looking for the absolute smallest possible way of taking 120VAC mains and getting it down to 12VDC. Is there another way of performing this without using a big bulky transformer? I'm just a hobbyist and I have done some searches online, such as offline switchers. Not exactly sure what they do. If anyone could give me some advice I would appreciate it. Thanks -Chris

The last time I was in Rat Shack, they had wall warts smaller than a pack of cigarettes, with awesome specs, like 12V 1.5A and stuff.

Just shop around for ac-dc adapters.

Good Luck! Rich

"Chris Gentry" wrote in news:5-Gdnc2Qx8UPDwbbnZ2dnUVZ snipped-for-privacy@insightbb.com:

You would want an SMPS. What they do us convert the mains to DC, then convert to a high freqiency pulsed DC to a ferrite transformer (which is much smaller than it iron counterpart), which then is rectified and filtered to DC. Regulation is done by actively adjusting the waveform driving the transformer, using a sample of the output voltage.

These folks have them surplus at good prices:

I've read the comments so far and I've been to the sites mentioned. I've also got my dimensions and they are L 2.62" x W 1.81" x H 1.13". Basically the same size as a GFCI outlet that you put into an electrical box. I've not seen anything with those small of dimensions. Is it possible? I need less than 100ma. The power supply would have to fit into those dimensions along with a pic microcontroller and a relay(10A at 125VAC). Currently my design takes up the complete bottom of a two outlet electric box. One outlet is live and the other side is all control.

Basically what I'm wanting to do is make something that will control the other outlet (basic switch on and off at programmed intervals). I would put my control box into a standard 2 outlet box and wire it just like you do a GFCI outlet. Then wire the live outlet off of the control box. That way when you pressed a button on the front of the box you could turn the other outlet off/on.

That way when I forget to turn the outlet on, it will switch back on automagically after the alloted (programmed) time.

Thanks for your help.

"Chris Gentry" wrote in news:l6ednURsB_KsdgbbnZ2dnUVZ snipped-for-privacy@insightbb.com:

Depending on what controls the relay, you might be able to use a direct transformerless supply.

I'd even jump to say you may not make anything custom that connects to the AC line anyways. Use an X-10 outlet and build something out of a controller.