[GreenKeys] Of current loops and voltages.. (M15 20mA / 60mA)

[Ralph Mowery]

I often hit the reply on this list by habbit when I should be hiting the reply to all.

Some of the newer machines have a conversion built into them that in effect a transistor drives a local to the machine high current magnet.  As the modle 15 was built before transistors were in use this option was not possiable at the time.   
  ----- Original Message ----- 
  From: drlegendre . 
  To: Alf Fisher 
  Cc: Green Keys 
  Sent: Tuesday, September 15, 2015 9:24 AM
  Subject: Re: [GreenKeys] Of current loops and voltages.. (M15 20mA / 60mA)


  Hi Alf,


  A couple other members wrote me (off list, not sure why) and your comments echo theirs. I already had the part about the requirements for high driving voltages - the inductance of the selector coils appears initially as a rather high resistance. And as with any relatively high resistance, it's going to require a relatively higher voltage to push any amount of current through it. 


  But I wasn't aware of the SS magnet driver circuit in the M33 and similar. I was also puzzled over the 20mA mode on the M15, which with 4X inductance seemed to me would seriously impede the cycle time if still being driven with 120V. Apparently it does slow things down, but not so much that the machine won't function. From the sound of it, it's a power-saving compromise intended for use when multiple machines are installed in somewhat close proximity. 


  Best,
  Bill

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20150915/a6adffe8/attachment.html>