View Single Post
  #3  
Old 29-12-2010, 04:42 PM
wasyoungonce's Avatar
wasyoungonce (Brendan)
Certified Village Idiot

wasyoungonce is offline
 
Join Date: Jul 2006
Location: Mexico city (Melb), Australia
Posts: 2,336
All ST4 does is supply an earth pulse on either Ra+. Ra-..etc etc.

In the early days...this "earth" switched a relay coil which in turn supplied pwr to drive a motor etc.

Generally nowadays it is used to switch a opto diode or even the emitter of an NPN transistor..or base of a PNP transistor.

In this pic the ST4 command (from Rj11 pin 6..from the autoguider) is an earth pulse to a opto diode...that drives a phototransistor.

In other words..the autoguider outputs an earth pulse (as appropriate commanded by guide software, either Ra+ or so on) which is used to command a drive motor system to move.

Hope this helps.
Reply With Quote