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  1. C

    555 Timer Push-On, Push-Off but with timer as well

    Here is the push-ON push-OFF circuit you need:
  2. C

    Door Alarm Help Please

    Do you want the alarm to go off after 10 seconds?
  3. C

    Audio transformer for crystal set help

    See talkingelectronics.com website for a very large article on CRYSTAL SETS and how to create an amplifier with and without a transformer.
  4. C

    11x42 LED Matrix with Arduino UNO

    One of the drive lines has only one LED on at a time or no LED. That's the line you put the resistor. 9% of the time is not going to give very much brightness and you will need sinking transistors. You are much better off the have a run of 5 and a run of 6
  5. C

    how to find out current in each resistors

    Your breadboard is not the same as the circuit. Use the web to find the value of 3, 4, 5 in parallel: http://www.1728.org/resistrs.htm
  6. C

    12v to 5v

    The minimum is 1,000u per amp.
  7. C

    Help with using shift register to expand uC output

    Start by simplifying everything for instance d'18' is .18 a file or register in a delay will 255 or 256 times without having to load it at the start. This saves 2 lines of code. Use a table. This will simplify the listing. See talkingelectronics.com website for .asm guides and a complete...
  8. C

    Simple LED timer circuit

    All the above circuits are absolute RUBBISH. You need the first circuit wired as a SUPER ALPHA pair with two transistors.
  9. C

    momentary +12VDC on input to flip the polarity of +12VDC on output for 10 seconds

    You have to wait before reversing a motor. The above circuits will not work. I have a project called To-Fro that reverses a train. It uses a micro and 2 relays. That's what you need.
  10. C

    PWM Circuit project help

    You don't need the transistor and 1k. The 555 will drive the LEDs directly
  11. C

    Help $ home work.

    First of all, that thing with "a" and "k"on it is NOT a light bulb.
  12. C

    Electronic help

    For a "normal" or "Common" or "general purpose" transistor, commonly called a bi-polar transistor because it needs Valium to maintain its operating parameters, you need to increase or "supply" or "deliver" a voltage on the base that is higher than 0.55v. Once this voltage is present on the...
  13. C

    Electronic help

    "All of the useful circuits have already been designed" "Designing a totally new circuit is something almost no one ever does." and "all electronics knowledge can be put into a book of 300 pages."
  14. C

    12v Battery Charger Circuit with Auto Cut off

    "http://www.circuitsgallery.com/2013/04/automatic-battery-charger-controller.html" This is just a badly designed circuit. It will not deliver more than 2 amps and the hysteresis value is unknown.
  15. C

    Problem in LM2576 circuit

    What load have you got connected to the output of the IC?
  16. C

    Adding hysteresis on a microcontroller

    You simply monitor the output of the ADC and the program provides the "hysteresis."
  17. C

    LED circuit help

    What is the diagram supposed to represent? Is is a string of diodes or LEDs??? If is is LEDs, 12v will not be sufficient to produce any illumination.
  18. C

    LED circuit help

    " resource section here for 'anything led'." There are lots of mistakes in this resource, including this diagram: (Image 2.4 from http://www.blue-room.org.uk/lofiversion/index.php/t32607.html)
  19. C

    Can I repair this PCB ?

    Just use fine enamelled wire.
  20. C

    Need professionally made circuits to control heaters using PWM and MOSFET

    Look . . . I think this whole requirement is way over your head and we are not going to be able to help someone who is transferring 40 amps in a design. You have to look at electrical emissions and get the whole project certified before you can sell it to the public. Where are you going to...
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