From: frank_...@hotmail.com   
      
   On Monday, June 19, 2023 at 9:55:06 AM UTC-7, cybernesto wrote:   
   > > Yes it will run from a generic 9vdc supply, but doesn't keep time    
   > > correctly    
   > > that way.   
   > That's strange. You are sure that it is not a switching power supply?   
   > I think I have enough spare parts to try the circuit you suggest,    
   > > using a 9v (AC) transformer and bridge rectifier. It may need a bit of    
   > > additional smoothing in the power supply. I think there's only a 100uf cap    
   > > or two in the Cricket! itself.   
   > Indeed. 1000uF are actually better.   
   > > There is a 555 chip as well, and if I hook it up to 14vdc or so it will    
   > > keep reasonable time. The speed of the clock seems to fluctuate a bit with    
   > > the input voltage. I wondered if it was a backup time base or something.   
   > The 555 oscillator is used together with some inductors to generate the -5V    
   > required by the speech chip. The frequency is not critical for this    
   > application.   
   > > Based on the regulator it should be ok up to 18 volts but I didn't want to    
   > > go that high. There's also a small potentiometer which I suspect may be    
   > > related to a secondary time base.   
   > The potentiometer is used by the speech chip to set its RC oscillator    
   > frequency to about 160kHz.   
   > > you talked about. I put new electrolytic capacitors in mine so don't    
   > > really    
   > > want to open it back up again.   
   > Good idea. I have two and both stopped working because of some leaky    
   > capacitors.   
      
   Also, rather than remove the rubber feet, you can just peel from the outside   
   corners and slip a phillips screwdriver underneath to get at the 4 mounting   
   screws.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)