From: phil_a@tpg.com.au   
      
   "John L Stewart"   
      
   >>   
   >> ** A " tone burst gate"  is a very handy tool for *speaker* testing  -   
   >> I built a kit version as published in ETI magazine ( ETI 124)  about   
   >> 30 years ago and it gets regular use. The circuit consists of just three   
   >> 4000 series CMOS and two op-amps -  plus a +/-15V psu.   
   >>   
   >> Input can be any frequency from 5Hz to 50kHz.   
      
   > If you have a copy of that ETI 124 schema   
      
      
   ** No such luck, I would have tossed the relevant mag about 10 years back.   
      
   There is no archive of old ETI stuff and the copyright holders are  "   
   Silicon Chip " magazine here in Sydney.   
      
   http://www.siliconchip.com.au/   
      
   I see no mention of that fact anymore.   
      
      
   ....  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)