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  1. Sunnysky

    4066 switches leaking in sample and hold circuit?

    Yes this discharges, the cap to 0V on both sides, but does not alter the Pot voltage. Not sure what the point of this circuit is.
  2. Sunnysky

    4066 switches leaking in sample and hold circuit?

    the pot value * C is your problem possibly , try 5k on switch out to ground.
  3. Sunnysky

    Voltage Converter or Not?

    the board needs 1 LiPo. 3.3~4.5 is spec'd the arduino needs 2 LiPo with 5V LDO with <1V dropout definitely not a 2A Zener. ok?
  4. Sunnysky

    4066 switches leaking in sample and hold circuit?

    can you redraw entire cct? Q1 in this link Is actually an inverted pulse, not what is needed. https://www.electronicspoint.com/attachments/s_h-png.20729/ 5 seconds ??
  5. Sunnysky

    Temporary magnetic switch?

    can you restate the requirement without magnets? Inputs = ? decimal switch , input clock, & trigger reset? Outputs = buzzer on last count to match input ?
  6. Sunnysky

    4066 switches leaking in sample and hold circuit?

    if Vbe= then collector current=0 then Resistor voltage on supply and collector side should be same. which is? 9v if not check my assumptions or bad part or ESD damaged CD4066
  7. Sunnysky

    4066 switches leaking in sample and hold circuit?

    +rail should be 9V for pullup R on collector.
  8. Sunnysky

    VR machine problems

    It's hard to imagine how the parallel port is used. Normally r/w signal 8 bits and strobe, at a 50kHz rate as I recall. https://en.m.wikipedia.org/wiki/File:25_Pin_D-sub_pinout.svg
  9. Sunnysky

    Repair delaminated flex circuit

    right . epoxy is compatible but non-serviceable, it just looked like a solder joint near there that needs to be checked.
  10. Sunnysky

    Solar charger circuit help

    Varying power load R to determine V vs I of PV panel. You can skip that and just use a little suitable 6V battery or a really big polymer superCap. Garden lights can barely keep 3V LEDs glowing bright for long which are only 20mA
  11. Sunnysky

    4066 switches leaking in sample and hold circuit?

    it depends. if you tried and sounds ok...
  12. Sunnysky

    Onboard charger repair. Value of ZD?

    The bulged cap,is from out gassing due to excess heat and ESR which degrades performance. and causes spikes in voltage from current pulses. A 12V fan then implies a need for a 12V Zener. The fan represents 1.6W/12V=133mA. or Z= 12V/0.133A= 90Ω. Now the 220 red-red-blk is actually a 22Ω part...
  13. Sunnysky

    4066 switches leaking in sample and hold circuit?

    Assuming bounce time is <30ms worst case , one solution is to use the leading edge to trigger a retriggerable 1-shot of 30ms where it's output leading edge triggers a 2nd one shot of 30us. Connecting the pins and choosing the RC time constants is easy for any design engineer with a schematic...
  14. Sunnysky

    4066 switches leaking in sample and hold circuit?

    that's better 30μs, then would be good. much less and the switch cannot compete the charge for a rapid change in voltage. using my est. 10RC = 10*300Ω*0.01μF= T= 30us Then we need to know the switch voltage and impedance and if there is contact bounce or if it is already denounced to make...
  15. Sunnysky

    Water Pump Reference or S/N

    never seen anything like it. IF I were to hazard a guess, Peltier heater on Red+ Black- and reversible impeller pump fan on green , white.
  16. Sunnysky

    Solar charger circuit help

    These garden PV's supply very little current needed for a DC-DC converter. Try a passive R load test to verify first, then use a battery to charge up before trying the third test of using a DC-DC converter.
  17. Sunnysky

    Onboard charger repair. Value of ZD?

    Service manual is likely to be non-existent, certainly a proprietary document. J1 function may give the clue for voltage. With 220 Ω connection to 12V to bias the Zener and the power limitations of both parts, it is likely for some off board function that needs a lower voltage like 9V or 5V. I...
  18. Sunnysky

    Repair delaminated flex circuit

    If you are certain the solder joints are not intermittent, you can use clear epoxy , with a toothpick applicator. It looks like panel push buttons. Can you test the functions on the connectors?
  19. Sunnysky

    A lot of old electronics (NiB), and very little knowledge about it.

    I remember going with my boss at a contract MFG factory and taking pallet loads of reeled parts and tossing them into the BFI scrap container. We were throwing them like frisbees for fun. His fun was that as an accountant he knew we was getting more in tax credits for scrap than they were...
  20. Sunnysky

    4066 switches leaking in sample and hold circuit?

    What is you circuit sampling. 1us won't work on 9V with 0.1uF because the ON resistance is ~300Ohms or less @9V. thus need 1ms pulse. Do you really need 1us? then what hold time?
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