Newbie needs variac info
- Thread starter Burke
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mhardy6647
Lunatic Member
10A sounds reasonable. Thats 1200 watts at 120V, y'know?
outlawmws
On the Run
Burke,
Another way is using what has been termed a dim bulb tester. This has an advantage as you can use it to verify if a transformer is shorted as well as bringing a piece of gear up gently, and reforming caps. This is especially nice if you aren’t doing it all the time. Variacs can get pricy, and hard to justify the cost.
Basically it is a light bulb wired in series with the power chord.
Like this:
o<<---o-(bulb)-o-----o<<--------+
|
120_AC_lines________outlet_____Radio
|
o<<------------------o<<--------+
Which I know will be hard to follow since forum pages ignore blank spaces. Ignore the underlines on the 120 line, my attempt to make it work…
Different watt bulbs produce different voltages.
bulb wattage__ohms resistance___resulting Voltage @121VAC
40________________26______________67
60________________19______________81
100_______________10______________91
150_______________7.5_____________100
240_______________5 ______________110
Again spacing problems but you should get the idea.
These old threads talk a lot about the device, unfortunately the pics are mostly gone due to an AK server glitch years back.
http://audiokarma.org/forums/showthread.php?t=25028&highlight=dim+bulb+tester
http://audiokarma.org/forums/showthread.php?t=41523
And a link to a web site on how to use and build it (with lots of test/use advice):
http://antiqueradio.org/dimbulb.htm
My tester as of 2+ years ago:
1 - The complete tester, I wired it through a GFIC, just because I had one around. Also provides a safe place to plug in gear at full voltage.
2- I wired thru a switch, and broke the link between the 2 outlets of the regular duplex outlet, isolating one side, placing the 2 sockets in series. (wire to the side you broke the link on)
3 – this is the tab on the receptical you bend and snap to isolate, on side only, the other is left intact.
Going back to the pic 1, I used an old plug in light socket to one socket (it dosn;t matter which) to provide the “load” that makes it work. And the remaining socket is where you plug in the gear you want to test or use on a lower voltage…
This can be built a lot simpler, and the web page I linked to will show one. I went this way because I had the stuff for it in the garage. I didn’t buy anything except the bulbs I needed but didn’t have.
Another way is using what has been termed a dim bulb tester. This has an advantage as you can use it to verify if a transformer is shorted as well as bringing a piece of gear up gently, and reforming caps. This is especially nice if you aren’t doing it all the time. Variacs can get pricy, and hard to justify the cost.
Basically it is a light bulb wired in series with the power chord.
Like this:
o<<---o-(bulb)-o-----o<<--------+
|
120_AC_lines________outlet_____Radio
|
o<<------------------o<<--------+
Which I know will be hard to follow since forum pages ignore blank spaces. Ignore the underlines on the 120 line, my attempt to make it work…
Different watt bulbs produce different voltages.
bulb wattage__ohms resistance___resulting Voltage @121VAC
40________________26______________67
60________________19______________81
100_______________10______________91
150_______________7.5_____________100
240_______________5 ______________110
Again spacing problems but you should get the idea.
These old threads talk a lot about the device, unfortunately the pics are mostly gone due to an AK server glitch years back.
http://audiokarma.org/forums/showthread.php?t=25028&highlight=dim+bulb+tester
http://audiokarma.org/forums/showthread.php?t=41523
And a link to a web site on how to use and build it (with lots of test/use advice):
http://antiqueradio.org/dimbulb.htm
My tester as of 2+ years ago:
1 - The complete tester, I wired it through a GFIC, just because I had one around. Also provides a safe place to plug in gear at full voltage.
2- I wired thru a switch, and broke the link between the 2 outlets of the regular duplex outlet, isolating one side, placing the 2 sockets in series. (wire to the side you broke the link on)
3 – this is the tab on the receptical you bend and snap to isolate, on side only, the other is left intact.
Going back to the pic 1, I used an old plug in light socket to one socket (it dosn;t matter which) to provide the “load” that makes it work. And the remaining socket is where you plug in the gear you want to test or use on a lower voltage…
This can be built a lot simpler, and the web page I linked to will show one. I went this way because I had the stuff for it in the garage. I didn’t buy anything except the bulbs I needed but didn’t have.
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