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  1. AnalogKid

    Drone flasher

    4-1/4 minutes is the period of a full cycle. Tweaking the clock frequency up a bit makes this an even 4 minutes. That's 2 minutes off (the initial delay requested), then 2 minutes of beeping every 2 seconds, 2 minutes quiet, beeping, quiet... ak
  2. AnalogKid

    Drone flasher

    Since you get the GPS location data only if the drone is transmitting it, that's a whole buncha battery power. Hopefully you could zoom in on it in less than an hour, and the batteries have that much gas left in them after the crash - correction, unscheduled stationary event. And, not to be...
  3. AnalogKid

    Drone flasher

    First pass at a drone beacon. I don't like timers with very large capacitors,so this circuit divides down a higher frequency clock to derive the necessary timing signals. R5 sets the LED current, and should be calculated for the LED and battery voltage being used. Everything else can run on...
  4. AnalogKid

    Drone flasher

    The most configurable and lowest power solution is a PIC microcontroller, but then there's all of that firmware goop. It could run for months, but for you to come up to speed on the programming would take twice that. So... Sticking to hardware, I've got an idea for this. One chip, two...
  5. AnalogKid

    Low voltage drop 8 amps Ac to DC power converter

    Note that the issue with the filter capacitor size is that if the cap is too small for the power being moved, the ripple voltage at the input to the regulator can be so big that the negative peaks go below the minimum value needed for clean regulation. The best way to see this is with a scope...
  6. AnalogKid

    Low voltage drop 8 amps Ac to DC power converter

    Also, 3300 uF is not nearly big enough to filter 8 A. After the diode bridge you should have around 18 V peak at C1, and there will be at least 1 V drop across the regulator (Vbe will be greater than 0.7 V at 3 A collector current.). That leaves less than 5 V of headroom, so you need around...
  7. AnalogKid

    Relationship of frequency and capacitance.

    About the capacitor plates, you have it backwards. All other parameters being equal, the closer the plates are the higher the capacitance (and the lower the voltage rating). This is partly because of the inverse square law. As distance increases, a charge exerts less force. So the thinner...
  8. AnalogKid

    Basic Toggle Switch Circuit

    Second pass. This one has a single monostable for consistent output pulses rather than two edge stretchers, and a larger holdup capacitor to assure the turnoff pulse. Note that none of the component values or tolerances are critical. ak
  9. AnalogKid

    Basic Toggle Switch Circuit

    1. Yes. 2. That's what I get for using someone else's library. Corrected files attached. 3. No. System 5V comes in from the USB connection, and is decoupled by D1 and filtered and stored by C1. +5V powers the 4093 and the turn-on pulse former C2/R1. When the USB 5V goes away at turnoff...
  10. AnalogKid

    Basic Toggle Switch Circuit

    Here is a first pass at using USB for both power and signalling. If Ground isolation is needed, Q1 can be replaced with an optocoupler. ak
  11. AnalogKid

    Working with an RC timer and a transitor to power a high current device

    If that's the intent, why the large cap and large resistor, a clear sign of a delay requirement? ak
  12. AnalogKid

    Broken LED detector

    A scanned LED array can have constant current source or sink drivers, or simple current limiting resistors. Either way, there is an impedance that creates a voltage drop, and that drop can be measured or compared to determine if there is an open circuit. If you want to identify which LED has...
  13. AnalogKid

    Basic Toggle Switch Circuit

    Misunderstood your comment. Given that there is a pulse circuit driving the switching transistor, having it make a pulse on power up is easy. However, there is a logic problem if the pulser has to be triggered by removing its own power. Hence, a small energy store to complete the pulse...
  14. AnalogKid

    Basic Toggle Switch Circuit

    True, but 100 uF to 470 uF at 10 V should be enough holdup to power a pulse before the cap runs dry. ak
  15. AnalogKid

    Ethernet to fiber optic converter

    There are many different Ethernet copper and fiber protocols and speeds. Which ones do you want to use? ak
  16. AnalogKid

    Basic Toggle Switch Circuit

    Just remembered another option common in Asian designs but less so in the US, a single chip on/standby controller. Switch interface and debounce, flipflop, and a small power MOSFET all in one package. That might be U3. If you can work through the PCB traces and determine that one end of the...
  17. AnalogKid

    lm386 and electret microphone problem

    Search for transistor microphone preamp circuit for many examples. Here is a simple one: http://easy-electronics4u.blogspot.com/2012/01/simple-one-transistor-microphone.html Also, there are threads on this forum about this. ak
  18. AnalogKid

    Basic Toggle Switch Circuit

    The power switch S3 is a SPST momentary TACT switch, so there is a toggle flipflop circuit somewhere. The latch could be built into the audio amp IC, but probably not. Can you read any lettering on U3? Also, the switch circuit might not be toggling power; it might be toggling an On/Standby...
  19. AnalogKid

    Working with an RC timer and a transitor to power a high current device

    You have a couple of options. The 120K resistor is starving the base of the current it needs to turn on the transistor enough to sink enough current to make the piezo audible. (A long a messy sentence) but when you decrease the 120 K, the time delay will decrease. If you decrease the 120K to...
  20. AnalogKid

    Basic Toggle Switch Circuit

    Not all latching pushbutton switches remain indented in one state and extended in the other. How sure are you that the switch is not latching? ak
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