[GreenKeys] 120vdc at 4-5 amps?

[Alf Fisher]

Hi Guys,
I reckon you need around 85 volts into the rectifier to get around 120 DC out.
A couple of 20-0-20 transformers with secondary windings in series wouldn’t be far off if you get the phasing right.

Alf
G3WSD


From: hwhall at compuserve.com 
Sent: Wednesday, May 02, 2018 2:19 AM
To: ksweek at mindspring.com ; GreenKeys at mailman.qth.net 
Subject: Re: [GreenKeys] 120vdc at 4-5 amps?

Couple ideas:
1.  Start out with the isolation transformer idea, find out what the final DC output is when rectified & filtered, cut into the transformer & take off some turns.  
2.  Make the above power supply but feed it with a variac instead of cutting up the isolation transformer.


Wayne
WB4OGM


-----Original Message-----
From: ken Schwieker <ksweek at mindspring.com>
To: GreenKeys <GreenKeys at mailman.qth.net>
Sent: Tue, May 1, 2018 6:25 pm
Subject: Re: [GreenKeys] 120vdc at 4-5 amps?


If you use an isolation transformer you will end up with considerably more than 120 volts dc after rectifying and filtering. One possible solution is to get a variac, remove all the center hardware
and wind enough turns of insulated wire for the secondary to produce the needed voltage.
Ken S 

At 11:13 AM 5/1/2018, you wrote:

  No, I don't need to run 100 loops at once. I have several pieces of gear with 120vdc motors and it would be nice not to have to plug/unplug them one at a time on my 1A supply.
  Any suggestions about where to find a suitable transformer? -Â  Diodes and caps are no problem. I'll keep an eye out at the Dayton hamfest.

  Nick England K4NYW
  www.navy-radio.com

     Virus-free. www.avg.com  


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