[GreenKeys] A little Kleinschmidt help needed

[Bruce Gentry]

I had thought about using a bridge, but the inductive kick in the 
selector magnet coil when the loop opens would cause current flow 
through the bridge and slow the drop of the magnet. The solution was to 
add another diode after the bridge. The current can flow to the magnet, 
but when the loop opens the added diode blocks the kick from reaching 
the bridge and the drop of the magnet is not delayed. The reason for all 
of this is so the printer and reperf can be patched in or out of the 
loop without needing to worry about polarity or using reverse patch 
jacks or a reverse cable.

     Bruce Gentry, KA2IVY



On 11/22/17 12:29 PM, Duncan Brown wrote:
> Bruce,
>
> The KLI TT-4 used spring bias, but all the other KLI units after that 
> used electrical bias (electromagnet plus permanent magnet).
>
> Just reverse the leads, or use a bridge rectifier.  The Mite machines 
> used a bridge on their loop input to get away from being polarity 
> sensitive.
>
> Have fun,
>
> Duncan
> K2OEQ
>
>
> On 21-Nov-17 23:52, Bruce Gentry wrote:
>> I am working on getting a radio hut with Collins URG equipment in it 
>> working. The TTY gear is all Kleinschmidt- a KSR, TD, and reperf. 
>> They all work but certainly need cleaning and oiling. The KSR, 
>> however, is sensitive to the polarity of the loop current. The 
>> selector magnets use a permanent magnet instead of a spring, so the 
>> wrong polarity will cause the printer to "run open" even with current 
>> flowing. Is there any setup or adjustmen that will allow the loop 
>> current to flow in either direction, like a model 15 or 28? Is there 
>> a selector magnet available using a spring instead of the magnet?
>>
>>      Bruce Gentry, KA2IVY
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