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[on:]

I have been searching google to purchase a 120v ac isolated transformer to stepdown the ac voltage to something usable.  Does anyone have a link to a website?  I plan I building my own benchtop ac/dc transformer.  I realize I can buy a manufactured one, but I want this to be a learning experience.  Thanks!

[Reply #1 on:]

Hard to say because you haven't filled in your location.

I realize I can buy a manufactured one, but I want this to be a learning experience.

Not sure what you mean. They are all manufactured unless you wind your own coil.

[Reply #2 on:]

Hard to say because you haven't filled in your location.

I realize I can buy a manufactured one, but I want this to be a learning experience.

Not sure what you mean. They are all manufactured unless you wind your own coil.

I'll have to fix that, but for now I live in Arizona.   I meant I would like to build my own benchtop AC to DC converter.  I would like to buy a isolated AC transformer and all the electronic components needed to build the AC to DC converter.  I can find all the components except the ac transformer.

[Reply #3 on:]

If you don't need a large and expensive one you will probably have to make it your self. You can use two suitably sized step down transformers wired low to low and you would have created an isolated, current limited,  ~120v source.

You have also not communicated the intended scope of your project properly.
Power requirements?
Why would you strictly need a 120v-120v Isolated transformer?

If indeed that is what you need. It's hard to tell from what you have presented.

By design, transformers are isolated. They are electromagnetically coupled.

So I guess I am not really sure what you are asking for.

[Reply #4 on:]

Knowing the voltage & current rating you are looking for might be helpful.

Is Alltronics still in business over in Scottadale? It's been a number of years since I passed through that area. They often had a good assortment of surplus parts.

[Reply #5 on:]

Scratch that last suggestion, I meant circuit specialists and I see they're over in Mesa, now.

(Too early, need coffee.)

[Reply #6 on:]

what exactly is your learning objective?

I did a benchtop power supply project like 30 years ago and I can't imagine that will have the same learning value nowadays.

[Reply #7 on:]

 The learning objective is just that, "learning." The final outcome of this project
is to have a functioning benchtop variable AC to DC transformer from 1volts to maybe 24volts. I know I can purchase one on Amazon for a relatively low price, but I want to build one to learn the theory and the functionality.

[Reply #8 on:]

Scratch that last suggestion, I meant circuit specialists and I see they're over in Mesa, now.

(Too early, need coffee.)

I checked out their website and they seem promising. Do you happen to know of any other websites besides digikey or mouser?

[Reply #9 on:]

I've had good luck with http://www.allelectronics.com. They ship quick and their parts are as described. I see they currently  have 24V transformers at ratings from 1 to 20 amps.

No affiliation, other than I've been doing business with them longer than I can remember, which is... What were we talking about?   

You may find this helpful in getting your design started:
http://paginas.fisica.uson.mx/horacio.munguia/aula_virtual/Cursos/Instrumentacion%20I/Documentos/Reg%20de%20Voltaje%20SGS.pdf

Oh, and what you are building is normally referred to as a variable benchtop power supply. A transformer is only the part that steps the AC voltage up or down, or matches impedances.

Good luck, and don't forget to install fuses! They're a lot cheaper than components or a trip to the ER!

[Reply #10 on:]

The learning objective is just that, "learning." The final outcome of this project
is to have a functioning benchtop variable AC to DC transformer from 1volts to maybe 24volts. I know I can purchase one on Amazon for a relatively low price, but I want to build one to learn the theory and the functionality.

no objections to the learning part. just merely suggesting that there might be more beneficial areas to spend your resource on (perhaps build a switching power supply?). as it is like learning vacuum tubes circuit. its a bit outdated.

[Reply #11 on:]

You can make a 2.5 to 40v supply with just a lm317, well not much supply mostly a reference at any more than 20v any current draw would be ridiculous
Gotta agree if you made an adjustable switching supply it would be usefull, effecient and plenty experience

[Reply #12 on:]

P.s while your at it why not a dual adjustable supply?

[Reply #13 on:]

I believe these people are in Arizona

http://www.goldmine-elec.com/

[Reply #14 on:]

Here are some drawings for a Power Supply... Good Luck in the contest.