"How To" for a DIY phase inverter?

[egr]

I'm looking for a schematic or "how to" for a stand-alone phase inverter.

I use a lot of consumer electronics and toys in recording and whenever possible (when the source is stereo) I record all audio from one side and noise floor only from the other side so I can phase flip and eliminate the hum, hiss, etc. I'd love to be able to do this in real time. All the in-line phase inverters I've found are pretty pricey and also set up as XLR. I just want to invert a single mono signal.

What should I be looking for? Googling isn't helping at all.

[The Scum]

<Pedantry>Phase? Or Polarity? </Pedantry>

In passive circuitry, you can use a transformer to invert polarity. Just wire the secondary backwards. If you're using noisy toys and stuff to begin with, then even a cheapo 600:600 modem transformer should be sufficient. Mouser have some for a few bucks each, such as PN 2TU016-RC.

If you want active circuitry, Google for "op-amp inverting amplifier."

[egr]

Using a transformer is very doable, I think. Something like this maybe? http://www.radioshack.com/product/index ... Id=2103254

I also run into impedance issues pretty often so this is definitely worth learning about.

[The Scum]

That's an output transformer...intended to let you drive an 8-Ohm speaker from a wimpy solid state output. You'll lose a lot of level with it, trading voltage for current.

I'm assuming you want the inverted signal at the same level as the original? If so, you need to primary:secondary ratio to match. 600:600 is the most likely configuration.

If you're going to get very deep into DIY, I strongly recommend weaning yourself from the Radio-controlled-car Shack, and dealing with real distributors. Mouser treat me very well, and they stock parts that are good for audio. Digikey is a close second, and Sparkfun is cool, but not especially audio-centric.

[egr]

I'm assuming you want the inverted signal at the same level as the original? If so, you need to primary:secondary ratio to match. 600:600 is the most likely configuration.

Thanks for that. That's the kind of info I'm after but having a difficult time finding.

RS is pretty crappy but it's on my way home from work and is usually my first stop when I'm "prototyping". Convenience is a hellova drug.

[egr]

I just wired up one of the transformers you suggested. Works perfectly!

[crow]

Your stereo toy hum-cancelling technique sounds brilliant. I can't wait to try it!

[egr]

Your stereo toy hum-cancelling technique sounds brilliant. I can't wait to try it!

I'm assembling a few units and putting kits together this weekend. I'll post the sales page when it's up.