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  1. (*steve*)

    Please help: Build for GPS tracker with SOS signalling

    Closed by request (it was a toss up as to whether if so that it move it to the twilight zone)
  2. (*steve*)

    Smoothing a charging current for a phone?

    Even a buck-boost converter may do you little good. Unless you can generate sufficient power for the phone to use, it may not charge at all. Worse, the load may pull the output of the generator (solar or otherwise) down so that it actually can't provide power. You are FAR better off using...
  3. (*steve*)

    Detect AC Power supply

    On the optocoupler side, I would make the 1k resistor 10k, and connect it from the emitter to ground. The emitter should be connected to the microcontroller input pin.
  4. (*steve*)

    PWM setup

    We can do no more until you spend $5 on a cheap multimeter.
  5. (*steve*)

    help! Unknown prong type!

    2 pin din?
  6. (*steve*)

    PWM setup

    Your picture shows red. If you post a picture and something is clearly rendered incorrectly it would help a great deal if you say so. My advice about reading the forward voltage still stands. (Also about how you should calculate the string voltage and match it to the driver)
  7. (*steve*)

    PWM setup

    Measured, or assumed?
  8. (*steve*)

    Something zapped it

    @TerryD, swapping the speakers over to see if the problem stays the same or swaps with the speakers is a simple first step. However it is possible that the amplifier has damages one of the speakers, and doing this will damage the other one. Ideally we would test the speakers first by...
  9. (*steve*)

    PWM setup

    You absolutely must know the forward voltage of the LEDs, and then you must have enough in series so that the total forward voltage drop off in the range required by the driver. If they are in the range of 1.5v to 2v then 4 or 5 n series should work with the driver that requires a load of 6v to...
  10. (*steve*)

    GPS Satellites Visible But No Fix

    I believe selective availability is turned off these days (since May 2000 by a decision on the Clinton white house). And future satellites may not even have the capability included.
  11. (*steve*)

    How can I light a led from a scanner lamp using 1,25 V X 0.054 ma input ?

    No.
  12. (*steve*)

    Arduino LED help

    And in general, LEDs require some form of current limiting (for low power LEDs, typically a resistor).
  13. (*steve*)

    Powerbank battery level meter?

    If all the cells are equally charged and not under load (or being charged) then there are battery voltages that will correspond to empty, 1/4, 1/2, 3/4, and full.
  14. (*steve*)

    Powerbank battery level meter?

    If it is a lithium battery (or lead acid) then the cell voltage is an indicator of charge. For lead acid you also need to take the temperature into account.
  15. (*steve*)

    GPS Satellites Visible But No Fix

    We'll... You can also average over time. That's what my GPS disciplined frequency standard does. The accuracy of the reference frequency is partially based on it knowing where it is with respect to the satellites. While it can get an approximate value quickly, it improves over time (up to a...
  16. (*steve*)

    Looking to power a peltier with <9V

    If you search the internet you may be able to find USB powered drink coolers. These run a Peltier from 5V and at a fairly low current. You would certainly be able to power them from 4 1.5V batteries, but I would choose C or D cells (unless you can use rechargeable AA NiMH).
  17. (*steve*)

    Building a timed motor circuit

    One option is to have a disc with a hole in it that is rotated so the hole lines up, the rotated back again to block the opening. You could do this with a stepper motor or a servo, but either way the controlling logic would most easily be implemented in a microcontroller (think Arduino). If...
  18. (*steve*)

    How can I light a led from a scanner lamp using 1,25 V X 0.054 ma input ?

    There is plenty of power there to switch a load using a transistor. That signal can be used to switch power from another source, say a 9v battery.
  19. (*steve*)

    Question

    Congratulations. That's a question. Now go read the information about this section which tells you we are not going to give you answers. It also has guidance on what we expect you to do.
  20. (*steve*)

    Proper switches circuit breakers & fuses for a 60VDC system

    I see nothing particularly wrong with the advice you were given on the other forums. The general advice is that voltage and current ratings for switches must exceed the voltage and current being switched (other than allowing a safety margin, any additional is irrelevant). For fuses the voltage...
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