[Boatanchors] Ohms Law

[Barrie Smith]

I want to thank everyone for the help.  I'm especially pleased that I had not lost my mind with regard to Ohm's law!

I want to thank Robert for the idea of the "buck" transformer.  I just tried it with a 6.3 volt tranny.  It didn't get me where I wanted to be, but it did get me half way there.

I'll dig deep in my "junk" and find a 12.6 volt tranny.  That should get me right where I want to be.

Thanks again & 73,
Barrie, W7ALW
  ----- Original Message ----- 
  From: WA5CAB at cs.com 
  To: barrie at centric.net ; boatanchors at mailman.qth.net 
  Sent: Sunday, April 18, 2010 5:45 PM
  Subject: Re: [Boatanchors] Ohms Law


  Barrie,

  Others have already commented on the resistor question, so I won't.  But I will offer a suggestion that won't generate much heat at all   Get a 115 to 12.6 VAC @ 1.5 or 2 A filament transformer and use it to buck the line voltage to the large 5 VAC transformer down by 12.6 volts.  If part of the problem is that your selected 5 volt transformer is rated 115 VAC primary but your line voltage is for example 120, then it will reduce the line voltage by 13.1 VAC.  If the 12 volt filament transformer has two or three primary taps, you can do some further fine tuning.

  In a message dated 4/18/2010 5:40:39 PM Central Daylight Time, barrie at centric.net writes: 

    've been juggling 5 volt transformers all day, trying to find one that would actually produce close to 5 volts for a pair of tubes.

    They were all either too high in voltage, or too low.  One did give me almost exactly 5 volts, but it ran way too hot.



  Robert & Susan Downs - Houston
  wa5cab dot com (Web Store)
  MVPA 9480