RadioShack® Audio Output Transformer

Comments about RadioShack Audio Output Transformer:

A 2n2222 transistor, this transformer, and just a few other small parts make an excellent audio amp for simple ham radio projects. Where we once needed 2000 ohm phones, an 8 ohm set will do when this transformer is used.

Comments about RadioShack Audio Output Transformer:

I've used this tranformer for several Amateur Radio applications and it worked as expected.

The turns ratio can be calculated by taking the square root of the ratio of the impedances. In this case, the square root of 1000/8, or 11.18

Comments about RadioShack Audio Output Transformer:

I was planning on getting two of these audio transformers for use in building a ring modulator for a friend. At first glance they looked perfect, they had a center tap, they were labled "Audio transformer", their price was almost equal to the cost of buying them from a mail-order supplier, and best of all I could buy them from my local radio shack instead of ordering one online. The problem was that there was ABSOLUTELY NO usable technical information on the package, sure there was stuff like freqency response and coil impedance, but nothing about the model of transformer or the ratio of turns on the coil. I couldn't convince myself to buy it, I asked an employee about it and they asked another employee who simply said "it will work for what you need it to". That's just great, I need to have two transformers, both with center taps, and both with 1:1 coil ratios, and yet the only place that carries them locally doesn't have the proper specifications for me to determine if the component that I'm buying will actually work. That's not how electronics work, you can't just substitute one component for a similar one and expect it to work. Also for some reason when I visited not just one but two radio shacks, both of them only had one of these parts in stock yet I needed two, maybe just a coincidence. All in all I needed this product and yet there wasn't enough information available on the package or from the employees for me to make a purchase.

Comments about RadioShack Audio Output Transformer:

Transformer Specs (from the packaging):
Input Impedance: 1 kOhm at 1kHz (input is center tapped)
Output Impedance: 8 Ohms
DC Resistance (Input): 70 Ohms +/-20%
DC Resistance (Output): 0.62 Ohms +/-20%
Frequency Response: 300-10,000Hz +/-3dB
Insulation resistance: >100 MOhms @ 100VDC

Height: 0.625" (plus 0.196" tabs)
Width: 0.791"
Depth: 0.591"

Comments about RadioShack Audio Output Transformer:

A transformer spec should include all dimensions, the turns ratios, and the input/output impdedance as well as the frequency response and the weight.

Comments about RadioShack Audio Output Transformer:

Mix left and right channels together with 2, 1k resistors to one side of the 1k primary and ground the other. Connect the 8 ohm side to the XLR signal lines. Connect the shild to the XLR and the metal box containing the transformer, if metal. Do not connect the MP3 shield to the box, keep isolated. Works with walkmans, boom boxes, computers too, any headphone jack.

Comments about RadioShack Audio Output Transformer:

Interesting, the Web Page does not provide impedance specifications, but the package that I have in hand does. It is:

273-1380
Audio Output
Transformer
1K ohms center-tapped
to 8 ohms

-

Comments about RadioShack Audio Output Transformer:

I've never had one of these transformers disappoint (well, except when I accidentally ripped the lead off...)

I've used these for all kinds of things. Powering neon lamps, small flouro lamps, audio phase splitting, and even a 400V B+ tube circuit (though it couldn't handle the current and got hot, it didn't arc over and I was able to reuse it.)

Comments about RadioShack Audio Output Transformer:

I used it on my telephone to create "Music on Hold". Very easy to do. Music goes on the 8 ohm audio winding and the other side is switched to the telephone line together with a load.

Comments about RadioShack Audio Output Transformer:

This is clearly the best quality miniature 8 ohm audio coupling transformer available. Not the cheap wax paper kind that have only one specific use. You can do amazing things with these little guys.

I use these for industrial/laboratory HV voltage inverter application with space limitation; 12-36 volt DC to 350 volt DC regulated boost converter to drive xenon strobe lamps.

8 ohm coil becomes the PWM controlled primary and the 1K is the secondary. Can charge a bank of capacitors to trigger the Xenon tubes nonstop for several minutes.

Other vendor transformers with similar size and rating would risk burnout and had internal arcing.

These RS units merely get lukewarm to the touch. No indications of dielectric breakdown or stress despite the alternative application. Quality windings as they are quiet.

Sure, I could have custom transformer and core designed and manufactured for my application. But this off the shelf part works fantastic for my purpose.

Hope that this product remains available for some time into future.