Help selecting and where to buy a low current transformer for dual power supply (opamps)

Hey kids, it's been a long time did anybody miss me?

My project is a inexpensive dual power supply for opamps.

It is my intention to use lm317 and lm337 in the to-92 case, hence the low current described below.

The specs that are relevant (as my limited knowledge allows) 60hz, 200ma, center tap, and 30v to 36 v across both output windings.

Of course I want it to be cheep, as I want many of them . Surplus would be good!

I am looking for advice about a specific model and vendor.

And while I have your attention, I have not been able to locate a source of inexpensive lm337 in the to-92.

Amazon has the killer price on the lm317 in a to-92 but a no show on the lm337 in the to-92

good day, and happy 4th to all that read this post!

Why does your circuit need a dual supply? Many opamp circuits are biased at half the supply voltage and use a few coupling capacitors then they work fine with a single supply.
Why do you need a voltage regulator? Opamps have a good rejection of power supply noise and their gain does not change when the supply voltage changes.

Edit: Fake and defective no-name-brand Chinese parts have killer prices.

audioguru said:

Why does your circuit need a dual supply?
Why do you need a voltage regulator?

Edit: Fake and defective no-name-brand Chinese parts have killer prices.

Click to expand...

Thanks for your reply.


No need here, it's just the direction I have chosen to go. Any idea on those transformers?

For $3 / 20 items, I can afford an education, so can Amazon, cause if I say they're bad, they're bad. Amazon loves me.

I was a little peeved tho, when I was charged 31 cents in tax, I believe that the vendor not Amazon is tasked with passing that to my state.

I don't have a lot of confidence that ShenZhenShi WuWei MaoYi YouXianGongSi will be remitting my 31 cents any time soon.
It really dosen't really matter, my state would just squander it.

Since you want them for audio, a toroidal transformer is a good idea as it minimizes stray fields which may cause hum

**broken link removed**

schmitt trigger said:

Since you want them for audio...

**broken link removed**

Click to expand...

what....................audio?

I mentioned 60hz, and while that is in the range of hearing, I was referring to, as the British say, the mains.

Mr. Trigger, I did get a chance to look at that transformer, that IS what I am hoping to find, but way too expensive.

My imagination wanders for a rational of cost, a bit of plastic and copper. I keep coming back to cost of manufacture.