[GreenKeys] Fw: Different Type Of TU

[JC White]

I made a variable speed unit for my TT-98 using transistor one-shots instead of ICs...   I want to try it with a 15 next... different design WITH ICs this time...

     
----- Forwarded Message -----
 From: Jeffrey D Angus <jdangus at att.net>
 To: greenkeys at mailman.qth.net 
 Sent: Sunday, May 22, 2016 7:05 PM
 Subject: Re: [GreenKeys] Different Type Of TU
   
 On 5/22/2016 8:45 PM, JC White wrote:
  
A couple of months ago I came across an article for constructing a TU
 that uses no tone filters at all.  The Dec 1991 issue of ELEKTOR, page
 18 - 20, has an FSK decoder based on a pair of one-shots.  Basically,
 they are set to react to the period of an incoming tone, so actual shift
 is not very important.  Neither are the actual tones, as long as the
 periods of the one-shots are adjusted (somewhat).  Having tossed
 together the circuit I am rather surprised how well it works.
 It's an interesting idea, one that's been around for quite a while.
 <http://zpostbox.ru/frequency_comparator_circuit.html>
 This was what was used for a speed control in the 1971 RSGB handbook,
 and a variation of which I used with the Lorenz motor speed control
 project.
 
 
 
 -- 
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com 
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