[GreenKeys] printing to KSR 28 was Re: OT: Radio Shack near bankruptcy

[Jim Haynes]

I'm not familiar with the Black Box things being offered, but there
is this caution.  Some 20/60 ma devices like Models 32, 33 and 35
operate at low voltage, so the converter circuit is pretty simple.
Models 15, 28, etc. normally operate with much higher voltage, so
the converter has to be able to withstand the voltage.

We used to use bipolar transistors like MJE-340 but then the "sold
state relay" chips became available, offering both high voltage and
optical isolation.  I've attached someone's document on the subject;
ask me by email if the attachment doesn't come through the system.

Jim W6JVE


jhhaynes at earthlink dot net
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