[GreenKeys] Loop supplies, or how to drive a selector magnet.

[Lester Veenstra]

In view of the wide variation in possible loop configurations, from just a
set of keyboard contacts with no resistance to a Model 19 with lots of
resistors and Polar relays, I still think there should be some dynamic way
(pot or active device) to set the loop to 60 or 20 ma.

 

Lester B Veenstra  MØYCM K1YCM W8YCM

lester at veenstras.com

 

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From: GreenKeys [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of
Jeffrey D Angus
Sent: Friday, May 20, 2016 12:31 AM
To: greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] Loop supplies, or how to drive a selector magnet.

 

What is the fascination with insisting on doing it wrong?

Transformer: $11.54
 
<http://www.mouser.com/ProductDetail/Pulse/DST5-120B39/?qs=sGAEpiMZZMvwUzoUX
IIvyU3kfM2h%252b089EV3piJz8kJE%3d>
<http://www.mouser.com/ProductDetail/Pulse/DST5-120B39/?qs=sGAEpiMZZMvwUzoUX
IIvyU3kfM2h%252b089EV3piJz8kJE%3d>
Rectifier: $0.68
 
<http://www.mouser.com/ProductDetail/Vishay-Semiconductors/2W10G-E4-51/?qs=s
GAEpiMZZMtQ8nqTKtFS%2fMRt2%2f0z7Bct2zH9CO%252bEpCc%3d>
<http://www.mouser.com/ProductDetail/Vishay-Semiconductors/2W10G-E4-51/?qs=s
GAEpiMZZMtQ8nqTKtFS%2fMRt2%2f0z7Bct2zH9CO%252bEpCc%3d>
Filter capacitor: $3.98
 
<http://www.mouser.com/ProductDetail/Nichicon/TVX2D101MCD/?qs=sGAEpiMZZMtZ1n
0r9vR22beeiJoI0EpC%2fkeSMD%2fcnuM%3d>
<http://www.mouser.com/ProductDetail/Nichicon/TVX2D101MCD/?qs=sGAEpiMZZMtZ1n
0r9vR22beeiJoI0EpC%2fkeSMD%2fcnuM%3d>
Series resistor: $1.69
 
<http://www.mouser.com/ProductDetail/Vishay-Dale/CW0101K800JE73/?qs=sGAEpiMZ
ZMtbXrIkmrvidDdY%2fwKIbxTCynlPbHo%252bnyU%3d>
<http://www.mouser.com/ProductDetail/Vishay-Dale/CW0101K800JE73/?qs=sGAEpiMZ
ZMtbXrIkmrvidDdY%2fwKIbxTCynlPbHo%252bnyU%3d>

For under $26 including shipping, and ONLY four parts you can have a 
proper 60 mA loop supply.



-- 
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com
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