Tree Light Work Around

Merry Christmas
Joethemechanic said:
I still think the 90 volts you get out of one of these fed backwards will power the lights fine.

View attachment 2580860
Click to expand...

Under its full rated 10VA load that transformer will have a 16VAC output. But under no load the voltage will be around 22VAC. This is because of its intentionally high iinternal impedance in order to limit the output current for protection reasons. And so I'd expect that when fed in reverse, the open circuit voltage would be around 12VAC x 120/22 = 65.5VAC. Under load the voltage would drop even further.
 
synchro said:
Under its full rated 10VA load that transformer will have a 16VAC output. But under no load the voltage will be around 22VAC. This is because of its intentionally high iinternal impedance in order to limit the output current for protection reasons. And so I'd expect that when fed in reverse, the open circuit voltage would be around 12VAC x 120/22 = 65.5VAC. Under load the voltage would drop even further.
Click to expand...

I figured they had a high impedance winding on the 16 volt side just from experience playing with them as a little kid. But I wasn't expecting the voltage drop to be that bad being that we are only loading it at about 1/20 amp on the higher voltage side
 
Joethemechanic said:
I figured they had a high impedance winding on the 16 volt side just from experience playing with them as a little kid. But I wasn't expecting the voltage drop to be that bad being that we are only loading it at about 1/20 amp on the higher voltage side
Click to expand...

I had a similar experience as a kid, shorting a screwdriver across the terminals of doorbell transformers and toy train transformers, and drawing sparks. :)
 
You must log in or register to reply here.
Top