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 Post subject: Transformer identification question
PostPosted: Jan Tue 10, 2017 5:43 am 
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Joined: Aug Sat 02, 2014 3:59 am
Posts: 542
Location: Brooklyn, NY 11217
I recently landed an Olson TT-456 transformer for $5. I have looked online, but found nothing to help.on its specs. It's got a 117v primary, and secondaries of 42vct, 47v and 6.2v. It is labeled low voltage, high current. The primary and each of the secondaries except the 42Vct are connected with 22AWG wire. The 42VCT secondary is 18AWG wire. OK, for the dreaded question. Any idea what the current rating on the secondaries would be? Pictures here. http://www.ebay.com/itm/Vintage-OLSON-E ... SwCGVX7TJh The lamination stack is about 2". It weighs about 10 pounds. And it is about 4" by 4.5". I can measure with a dummy load, but am just wondering what they are, ball park.


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 Post subject: Re: Transformer identification question
PostPosted: Jan Tue 10, 2017 5:59 pm 
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Joined: May Tue 30, 2006 4:46 pm
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Location: Santa Rosa, CA
One possibility is to compare to modern, well-spec'd transformers, like Hammond.

http://www.hammondmfg.com/266.htm

Yours should be good for at least 200VA. Can you put a resistive load on it and measure the voltage at say 5 amps output?

Rich


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 Post subject: Re: Transformer identification question
PostPosted: Jan Tue 10, 2017 6:16 pm 
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Joined: Apr Mon 18, 2011 3:52 pm
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Location: United States
There's an Olsen Electronics nostalgia Facebook page. Maybe someone there can find your info in an old catalog: https://www.facebook.com/OlsonsElectronics/


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 Post subject: Re: Transformer identification question
PostPosted: Jan Tue 10, 2017 7:28 pm 
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Rich, W3HWJ wrote:
One possibility is to compare to modern, well-spec'd transformers, like Hammond.

http://www.hammondmfg.com/266.htm

Yours should be good for at least 200VA. Can you put a resistive load on it and measure the voltage at say 5 amps output?

Rich

+1
compare to any known transformer----the total VA rating will be roughly proportional to the mass of the core......or--very crudely--to the total mass. 2 transformers of the same size and weight will tend to have the same VA rating.

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 Post subject: Re: Transformer identification question
PostPosted: Jan Thu 12, 2017 2:54 pm 
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Joined: Aug Sat 02, 2014 3:59 am
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Location: Brooklyn, NY 11217
Thanks guys. I guess my issue is trying to figure out how much power I can get from the 6.2v winding. I only need 750ma out of the 42 volt winding. I was hoping to get a 4-5A out of the 6.2v side, but I wonder if that is just for a pilot light or the like. I can try a resistive load I guess. I will need a 1.25 ohm 50 watt resistor. Not sure I have that. I may have a 50W potentiometer that is in that neighborhood. At least then I could measure the heat increase over ambient. It's times like these that I realize that I many have lost my mind.

I have also contacted the Olson Group on facebook. thanks for the tip!

Shawn


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 Post subject: Re: Transformer identification question
PostPosted: Jan Thu 12, 2017 6:16 pm 
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Location: Santa Rosa, CA
Quote:
I was hoping to get a 4-5A out of the 6.2v side, but I wonder if that is just for a pilot light or the like
.

What gauge wire on the 6.3V winding? For 5A, I would want at least 18 AWG.


Rich


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 Post subject: Re: Transformer identification question
PostPosted: Jan Fri 13, 2017 4:12 pm 
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Location: Brooklyn, NY 11217
The lead wire is 22, so it isn't going to get there. It's all really nice PTFE Kawasaki 600V rated wire.

Shawn


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 Post subject: Re: Transformer identification question
PostPosted: Jan Fri 13, 2017 6:01 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
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Location: Long Island
In lieu of a real spec sheet, you can try loading the transformer while monitoring the secondary voltage. Most radio and electronic power transformers are designed for a 10% drop in secondary voltage from no load to full load. So what you can do is measure the difference in voltage between no-load and desired load. If it drops less than 10% you're probably okay. Of course since this is only a rough estimate, one should monitor the temperature of the transformer under full load for a while to make sure it's staying within reasonable bounds.

Olson was a major importer of Japanese audio and test equipment, CB radios, and also sold a lot of parts, tubes, and small tools. Very similar to Lafayette in New York. Chances are your transformer was a generic version of the ones in many of their stereo receivers or amplifiers. So if you look up the service literature (eg. SAMS) of some late '60s-early '70s Japanese solid state receivers, you'll probably get a pretty good idea of what the transformer ratings were.

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 Post subject: Re: Transformer identification question
PostPosted: Jan Fri 13, 2017 6:02 pm 
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Need to know the actual winding gauge---leads can be smaller or larger.

#22 is good for ~5 amps in short runs---maybe more. the resistance of one foot of #22 is 0.052 ohms

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 Post subject: Re: Transformer identification question
PostPosted: Jan Fri 13, 2017 6:50 pm 
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The usual conservative figure for figuring the wire gauge for a transformer is 1000 circular mils per amp. At that you would need to use 13AWG (5184 circular mils) or two 16AWG in parallel (2581 circular mils each) to carry 5A. OTOH, 800 circular mils per amp would require one 14AWG or two 17AWG wires.

A lot of the choice of wire size depends on the allowable resistive loss which creates heat, the target temperature rise under full load and the ability of the transformer to dissipate the heat. It must be kept in mind that the minimum wire gauge for a given current is very different for a lead wire in open air and a wire buried inside the winding.

John

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 Post subject: Re: Transformer identification question
PostPosted: Jan Sat 14, 2017 9:36 am 
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I should have made clear that I was talking about #22 only as the lead wire.

The ultimate criteria in a transformer is usually temperature rise. This in turn is determined by the current in the primary and secondary.

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