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

[ampedtech]

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!

 

[audioguru]

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.

 

[ampedtech]

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.

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.

 

[schmitt trigger]

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**

 

[ampedtech]

Since you want them for audio...

**broken link removed**

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

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

 

[ampedtech]

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.