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  1. Alec_t

    Peak detector for piezo drum pad

    Doing what? It only does what you tell it to do (hopefully :) ), so you would have to program at least a polling routine. The datasheet should tell you the A/D conversion time.
  2. Alec_t

    Peak detector for piezo drum pad

    If the 22 channels are being constantly polled, the MCU would have to sample all 22 channels before the peak detector output has decayed significantly, so that output might need to be held for a while. What is the processing time required to handle one peak measurement? Edit: Bob beat me to it :).
  3. Alec_t

    Low Pass Filter For Ground And Neutral

    Welcome to EP! You can't guarantee that there will be 0V between Neutral and Gnd. Although they may be connected together at some point in a mains distribution system, wiring from that point on can pick up all sorts of voltages from spurious ground currents and interference. AGND is a reference...
  4. Alec_t

    Device powered by computer usb port but not USB phone charger

    Check the cable to see if any resistors are connected from either data pin to either supply coltage pin.
  5. Alec_t

    How takeover of the control done in standby redundant system?

    The trick will be to identify all possible faults that you think could occur. Even then, Murphy's Law dictates that you will miss at least one :).
  6. Alec_t

    How takeover of the control done in standby redundant system?

    How will you know when a PCB develops a fault and which PCB is faulty?
  7. Alec_t

    Lynx tablet

    Since you already have 3.7V connected into the battery terminals, if you also apply 5V to the charging input, as Bob suggested, what happens?
  8. Alec_t

    Lynx tablet

    If the Lynx queries the BMS (and we don't know if it does) it must expect some response; either a voltage or code or .... who knows? If it doesn't get the expected response it will sulk.
  9. Alec_t

    Back emf?

    The motor should have a back-emf protection power diode in parallel.
  10. Alec_t

    Davis Vantage Vue weather station: stop replacing battery

    At full charge the voltage is 4.2V, but this drops non-linearly as the battery discharges.
  11. Alec_t

    Lynx tablet

    Yes, the BMS circuit for protecting the battery. It may have detected that the switch-on/off characteristics of the 3.7V supply don't match a battery presence and gone into shut-down mode. If the Lynx queries the BMS it would then fail to start up. Just a guess. Since battery failure is no...
  12. Alec_t

    Motion sensor that senses motion not the change in temp

    Instead of having a heater on the arm you could illuminate it with an IR LED so that reflected IR gets to the PIR sensor.
  13. Alec_t

    Davis Vantage Vue weather station: stop replacing battery

    Here's the circuit I used (I think). The J107 replaces the 2N3189 I used. An 18650 could be used instead of the 3 alkaline cells. The blue and yellow traces are for temperatures of +60C and -40C respectively. If you do use a 18650, ensure it has a battery-protection circuit to prevent...
  14. Alec_t

    Davis Vantage Vue weather station: stop replacing battery

    That's useful to know. Just remembered: I replaced a 3V memory back-up cell in my O'scope with a stack of 3 or 4 partly-used AA alkaline cells and a crude regulator made using a JFET (2N3189, now obsolescent) from my junk-box. Perhaps something similar would suit your application?
  15. Alec_t

    Davis Vantage Vue weather station: stop replacing battery

    Do you know how low the cell voltage can go before the cell is regarded as dead?
  16. Alec_t

    Davis Vantage Vue weather station: stop replacing battery

    For current in the 1-50uA range, a power diode (e.g. 1N4007) drops about 50mV more voltage than a signal diode (e.g. 1N4148), if that's of help.
  17. Alec_t

    Davis Vantage Vue weather station: stop replacing battery

    A silicon diode will drop less than 0.6V if the current is only a few uA. If you're really concerned that 3.7V is too high then an alternative would be to use a couple of alkaline cells (nominally 1.5V x 2, but when fresh could be ~ 1.65V x 2).
  18. Alec_t

    LM2596

    Well, that's a DC-DC converter, not just a LM2596. It has only V+ and V- rails going to the USB connector. Perhaps your iphones are looking for specific voltages on the D+ and D- pins of the connector?
  19. Alec_t

    Led grow light diode replacement help

    :confused: Your LED light specifies mains AC input, 1200W, whereas the LED Driver puts out DC at 21-36V, 1.5A max. Clearly the LED Driver is not intended for that light.
  20. Alec_t

    Using Raspberry Pi to read signal generated by a function generator

    .... or a zero-crossing detector instead of the peak detector, if the waveform is bipolar.
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