[GreenKeys] Looking For Bits

[Jim Pruitt]

Hello Keelan:

Looks like a Hammond 187C120 at 12VA would more than do it for you.  At
least looking at their spec sheet pages from
<http://www.hammondmfg.com/186_187.htm> .
Mouser lists them but it is a non stock item at less than $10 at
<http://www.mouser.com/ProductDetail/Hammond-Manufacturing/187C120/?qs=sGAEpiMZZMv4oUrzpPKU3CkdIda8KQx%252bPVHaKkfyINc%3d>
.
Digikey also lists them at $10.68 but again a non stock item at
<http://parts.digikey.com/1/parts/1957156-transformer-chassis-mount-187c120.html>
.
I do not know if you could order one from Hammond directly or not.  Newark
says they currently have 28 in stock at $11.49 at
<http://www.newark.com/hammond/187c120/power-transformer/dp/50H6562>
each (but Allied and Newark have a minimum order of $50 or used to).

Jameco lists a stock number 221331 Isolation transformer but at almost $60
at
<http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&productId=221331&catalogId=10001&freeText=221331&app.products.maxperpage=15&storeId=10001&search_type=jamecoall&ddkey=http:StoreCatalogDrillDownView>
.Mouser I think has the 120vac pri 120vac seconday at 50ma transformers as
they seem to get used a lot in old AA5 and similar radios so that is just a
bit shy of your 60ma requirement if you go with a 60ma loop and not a 20ma 
loop.

The other thing is as you suggested and put two transformers back to back.

Good luck.

Jim Pruitt



----- Original Message ----- 
From: "Keelan Lightfoot"
To: "Green Keys" <greenkeys at mailman.qth.net>
Sent: Saturday, August 27, 2011 8:10 PM
Subject: Re: [GreenKeys] Looking For Bits


> 120V, 10VA-ish. A transformer with a few taps would be handy, as 160VDC 
> seems a bit high for my liking. A 90V tap would give me somewhere in the 
> range of 135VDC after rectification, which is more the level I am looking 
> for.
>
> - Keelan
>
> On 2011-08-27, at 8:01 PM, Martin A Flynn wrote:
>
>> What voltage and how many watts?
>>
>> Martin
>>
>> On 8/27/2011 10:52 PM, Keelan Lightfoot wrote:
>>> I'm looking to buy:
>>>
>>> 3. A 1:1 isolation transformer suitable for loop supply use. It would 
>>> seem these are quite hard to come by, even in the form of old shaver 
>>> outlet isolation transformers. I can get away with a couple transformers 
>>> back-to-back, but I'd like to do it in a cleaner way if possible.