Typical electron-over-hole bias.

ak

Positive "ground" is the bane of equipment intended for automotive use. And "center negative" on the power inlet is a terribly destructive NASTY TRICK done on some electronic devices, for purposes best described as nasty.

 

And "center negative" on the power inlet is a terribly destructive NASTY TRICK done on some electronic devices, for purposes best described as nasty.

Are you talking about a non-isolated voltage doubler off the mains? That was very common in low cost portable TVs in the 60's, although I associate it mostly with Philco. The problem was the voltage rating of the caps. A 200 V cap in a 160 V circuit is not a good plan. Throw in the heat from the tubes in a cramped space, and - POP. Replaced a few caps and diodes.

ak

 

Are you talking about a non-isolated voltage doubler off the mains? That was very common in low cost portable TVs in the 60's, although I associate it mostly with Philco. The problem was the voltage rating of the caps. A 200 V cap in a 160 V circuit is not a good plan. Throw in the heat from the tubes in a cramped space, and - POP. Replaced a few caps and diodes.

ak

NO, not the voltage doubles.
My gripe is the low voltage coaxial power plugs we see everywhere. Most of them have the center positive, BUT a number of producers invert the connection and make the outside positive, with the center pin the negative.
NOT ONLY does that provide a quick way to damage equipment, it also creates a serious fire hazard when connections are used in an automotive application. because most cars are negative ground connected to most of the exposed metal. A contact between the positive sleeve and the negative body metal puts the 12 volt battery across a few feet of rather skinny wire with easily ignighted insulation, protected only by a fuse, generally of a much greater rating than the wire.

 

My gripe is the low voltage coaxial power plugs we see everywhere. Most of them have the center positive, BUT a number of producers invert the connection and make the outside positive, with the center pin the negative.

IIRC, center-negative was much more common years ago, I think because this made the exposed center pin of the mating connector GND rather than something connected to a circuit part that could be damaged by ESD, etc. Then things started to shift to center-positive, which is unofficially universal now.

ak

 

It's a 1K center-tapped to 8 ohm audio transformer. radio shack may still sell them. the speaker if I remember right is 500mW 8 ohm.

 

Y'all scared em away. The TS, new to this website, has not posted since post #1 (June 4). Today (June 8) thus far nobody stopped to welcome him/her to AAC. IF @pcflyf77 is still with us, Welcome to AAC.

Yes, it's definitely an older circuit. But it worked way back then. There's no reason why it wouldn't' work today. As for the transformer, you have plenty of information to go on. Good luck with your project.