Uses for TV brightner transformers - Videokarma.org TV - Video

wa2ise · #1 01-04-2015, 10:45 PM

Most vintage CRT brightners used little 60Hz power transformers that convert 6.3VAC to around 9VAC. More accurately, they are autoformers. Okay, we avoid these things like the plague on CRTs, so what else could we do with these? I mean, in electronics work

Well, say you have some 8.4V heater tubes but you need its 6.3V equivalent. One of these autoformers will get you there. Yeah, how often does that come up...

Another use is in a series string set where you need an 8.4V heater tube, and all you have is its 6.3V equivalent. Put the string line into the 8.4VAC connection, and the tube on the 6.3V connection, and both to the other side of the transformer, and the other end of the string. The tube should be the same heater power as the original tube.

The series/parallel ones usually can produce about 12VAC from one end of its winding to the other, with taps at around 6.3 and 8V.

NoPegs · #2 01-04-2015, 11:40 PM

I'm planning to use some of the parallel-wired style ones (a true transformer with two windings) to float the 6X5s in my 1942 Zenith chairside as long as I can find room for them under the chassis. Might also do the same on the 6X5 in the admiral. (My brighteners I currently have feature an "isolate H-K shorts" connection option on them that doesn't alter the voltage, along with an option that does boost the voltage. Obviously I'm going for 1:1 for the 6X5s.)

wa2ise · #3 01-04-2015, 11:51 PM

Quote:

Originally Posted by NoPegs

I'm planning to use some of the parallel-wired style ones (a true transformer with two windings) to float the 6X5s in my 1942 Zenith chairside ...

You can also use 120V to 6.3V transformers of the same size for that service. This would offload the main power transformer some as well.

Electronic M · #4 01-05-2015, 12:52 PM

6X5s were prone to cathode to plate shorts (I've even seen it happen...Twice!), and that failure mode is more dangerous to the power transformers. If I were you I'd leave the filament of the tube connected, disconnect the diode terminals of the tube from the wiring, and then use some 1n4007 diodes to supply the B+.