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.   
      
      
   I was able to wire up a working linear, unregulated power supply using a 12vac   
   transformer into a full-wave rectifier then finally a 560 uf 35v capacitor in   
   series. The lower rating leaves enough ripple in the output to create the   
   120hz timebase clock    
   signal. The connector is a 5.5mm x 2.5mm center positive barrel jack.   
      
   I'm wondering if Euro units are hard-coded for 50hz instead of 60hz line   
   frequency? Or if the microcontroller is smart enough to tell based on the   
   pulse widths which speed it's running at? Does yours normally keep time   
   correctly?   
      
   BTW the caps to replace are five 100uf 25v and four 10uf 25v. Both Crickets   
   I've worked on needed a touch of new solder to be able to desolder, and both   
   had pretty dry caps. One unit was failed, one working but I could see leakage.   
   All marked "Liberty".   
      
      
      
   A list of components inside:   
      
   U1 - custom Street Electronics microcontroller 03-801-00   
   U2 - SN74LS02N - 2-input NOR gate   
   U3 - TL084CN  340B (TI) - J-FET Op-Amp   
   U4 - UA723CN  406E (TI) - Linear Voltage Regulator   
   U5 - TLC555CP - Timer/Oscillator   
   U6 - TMS5220NL  (TI) - Speech Synthesizer   
   U7 - AY-3-8913 - 3-voice Programmable Sound Generator   
   U8 - AY-3-8913 - 3-voice Programmable Sound Generator   
   U9 - LM386N - Audio Power Amplifier   
   U10 - LM386N - Audio Power Amplifier   
      
   Q1 - KS2N4401 - NPN transistor TO-92   
   Q2 - KS2N4403 - PNP transistor TO-92   
   Q3 - KS2N4403 - PNP transistor TO-92   
      
   REG - 3 pin TO-92 voltage regulator? (can't read markings)   
      
   RN1 - SCCO 10-9-5-R 47K(?) resistor network (Stackpole?)   
      
   XTAL - 4.9152 MHz (microcontroller clock / UART-friendly frequency)   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)