AC to AC conversion?

Before hurting myself with ac voltage, I just want to ask for advice for my project. How can I go from 110v ac to 40v ac as cheap as possible. I am going to put the 40v in a relay module for my project. Its going to run little to no amperage hopefully (roughly 50ma).

I am a noob so sorry for my bad questions.

A [u]transformer[/u] is what you want, but 40V is unusual and 50mA is unusually low (of course the transformer can be rated for more than the required current). 36V is probably easier to find if that will work.


Get them out of older equipment, on eBay or surplus dealers.

Great thank you guys for your help! How do I search for one to buy? Or if I get one from older equipment, how do I know if it will be the right part for me? When I search, I get really high priced ones or others that go from ac to dc. 36v will work fine for me though.

All I need the 40v to do is connect a circuit with a relay module.

Du You want to have 40 volt AC or 40 volt DC? For AC a 36 volt transformer is surely good but for DC, buy a ready, switched supply. 24 is one standard and maybe a 36 volt supply with adjustment can reach 40 volt.

Just 36v ac. When I search ebay, they are all really expensive or go to dc which I do not want.

Please be careful. You can kill yourself if you don't know what you're doing.

Be sure you understand about protective earthing, insulation, dielectric strength, creepage and clearance (esp. important if you have ideas to prototype mains-voltages on protoboard) etc etc.

@Blackfin It's true that persons have got kille by as low as 24 volts but that's extreme.

The part needing knowledge is the contact with mains, 110 or 220 volts. That voltage is not for playing.

Personally I've been making my own powersupplies, 220 to 5, to 12 and to 24 volts. And yes, I know what 220 volt feels like.....

I appreciate your concern. I'm not an electrician which is why im not doing anything too serious. Im just adding another way to turn on a device which I dont think will require too much skill.

It's definitely the primary side of things I worry about here.

You might check thrift stores or recycling places for doorbell transformers (usually 8, 16, 12 or 24 VAC) or the older style AC wall warts (the big heavy ones have a transformer inside, and can be opened up for use).

It is possible to wire the outputs of two transformers in series to get the sum or difference of the two individual voltages.

For any electrical work, a decent multimeter is an absolute necessity. Buy one and use it to check circuit or lamp continuity, voltages, etc.

Why not buy a ready mains to 36 volt supply? There are such ones having a selector for the output voltage.

oKeeg: All I need the 40v to do is connect a circuit with a relay module.

Just out of curiosity, what is the load/circuit being switched?

What is Your project really? What is the device You want to power up? Not knowing that You will be drowning in suggestions. Please, more detailed info.

Dare I suspect - XY Problem?