[GreenKeys] Loop Supplies

[Richard Knoppow]

     Well you can always make a bridge of four 1007's or lower voltage 
diodes.   The advantage of a bridge is that the ripple frequency is 
higher so the cap has a easier job smoothing the DC. Not a big deal but 
in the old days half wave rectifiers were usually economies.
      I figured out that c. 1950 there were at least a dozen transformer 
makers of general purpose transformers and maybe half a dozen more if 
you counted people like Dyna who made specalty items.

On 6/17/2015 6:09 PM, Lee Mushel wrote:
> Some things never change.   In 1960 the loop transformer of choice was 
> the Triad N-48X. Mouser has 20 in stock but I will admit it costs more 
> now: $14.
> The one I'm holding in my hand cost $1.50.....  I used to use a full 
> wave bridge since they were conveniently available at an electronics 
> emporium close to home.
> 73
> Lee   K9WRU
>
>     ----- Original Message -----
>     *From:* Jack <mailto:wa2hwj at att.net>
>     *To:* greenkeys at mailman.qth.net <mailto:greenkeys at mailman.qth.net>
>     *Sent:* Wednesday, June 17, 2015 5:52 PM
>     *Subject:* [GreenKeys] Loop Supplies
>
>     ZCZC
>
>     Everyone should have a reliable and available loop
>
>     supply for testing TTY’s, etc.
>
>     I have been using Hammond 187C120 transformers
>
>     which can be obtained from Mouser Electronics for
>
>     around $10.00, plus shipping. This transformer outputs
>
>     120V at 100 milliamps and has a small physical
>
>     footprint. Higher current ratings come with higher
>
>     cost.
>
>     All you need is a diode, electrolytic filter capacitor
>
>     and a current limiting resistor and you have
>
>     a “loop supply”. I use a 1N4007 diode, 40 mfd 450V
>
>     capacitor and an adjustable wirewound resistor of
>
>     approximately 2,000 Ohms for a 60 ma. loop.
>
>     Jack K0TTY
>
>     NNNN
>
>

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20150617/14f6a60d/attachment.html>