[GreenKeys] Fusing Requirements for Loop Model 26

[Ralph Mowery]

I don't really see how the current could go up if the loop is like most I
have used.  The roughly 2000 ohm resistor is to limit the current to 60 ma.
Resistors seldom short out,but may open.

Ralph ku4pt


-----Original Message-----
From: greenkeys-bounces at mailman.qth.net
[mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Jeffrey Angus
Sent: Thursday, September 19, 2019 6:57 AM
To: greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] Fusing Requirements for Loop Model 26

On 9/18/19 9:47 PM, Jim Cooper wrote:
> I think if you ever, ever found a 63mA DC fuse it would blow on
> the first mark transition, due  to surge current ...   I'm sure
> an 1/8 A fuse would  do just fine, maybe even a 1/4 A ...  the
> selector magnets are a lot more forgiving than transistors !!
>
> w2jc
The surge current in the selector magnet on the transition from
Space to Mark is zero. The entire purpose of using 120 v and
a series limiting resistor is to get the current in the selector
magnet moving quickly from 0 mA to 60 mA. t = L/R.

I explained how this all works a week or two ago.

-- 
"I am a river to my people."
Jeff-1.0
WA6FWI
www.foxsmercantile.com


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