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  1. BobK

    A Question on the m140 Laser Diode

    An LM317 can be easily configured as a current regulator. Check out the datasheet for the circuit. Bob
  2. BobK

    A small timer required.

    What happens if you push the button while it is still running? Does that really cause it to cycle off and on, or will it continue to run and give it another 4 hours? If the latter, the timer can be anything less than 4 hour to keep it running. Bob
  3. BobK

    Problems with iPhone 5V car power supply

    Yeah, they calculate out close enough, but as Alec suggests, 8.2K is a standard resistor and it actually comes out closer. Bob
  4. BobK

    What kind of chip is required?

    Google RFID. Bob
  5. BobK

    Leakage voltage in relay mecanical

    How long are the wires from the relay to the lamp. Anything more than a few cm might very well pick up an AC voltage by induction. Bob
  6. BobK

    PWM controlled DC motor using 2n3055: Is it okay? How can be inproved? + Proteus file

    You completely misunderstand the use of PWM to control a motor. By filtering the output, you have changed it a votage regulator and you are using a varying voltage to control the motor, which results in lower torque and failure of the motor to start at lower settings, when compared to running...
  7. BobK

    DIY voltage Regulator

    The burst of current needed for the gate can come from a decoupling capacitor. You don’t need a 1A supply to provide 1A pulses for a few microseconds to charge the gate. Bob
  8. BobK

    DIY voltage Regulator

    Steve’s point is that you do not need an LDO to go from 48V to 12V. It has no advantage over a normal regulator, which will regulate to 12V from any voltage over 15V. There is not even any difference in efficiency, while your Zener regulator is actually less efficient due to the wasted current...
  9. BobK

    Temperature sensor project

    Are you planning on paying for this, or do you expect someone to do it for free? Bob
  10. BobK

    Peak detector to A/D of PIC

    I am still not buying it. With a 220nF cap, the ADC should have no problem with sampling the output of your peak detector. Basically, the ADC is simply putting a much smaller capacitor in parallel with that capacitor when sampling, which should have no effect. The datasheet says 10nF is...
  11. BobK

    Function and their types

    The library function rand() does exactly that. It starts the random number sequence with a seed then, esch time called, computes a new random number and returns it, while keeping the global variable hidden. Also it is common (and recommended) to use accessor functions in C++ to return the...
  12. BobK

    Function and their types

    You can have any expression as an argument in the printf statement. You can replace "count" in your printf with "counter()" and it will work correctly. The way you have changed it, the function is not even being called. Bob
  13. BobK

    Peak detector to A/D of PIC

    If you can measure the voltage at the output, (presumably, the node marked cathode D1,) but the PIC is not reading it, I think it is your program that is in error. Try measuring a stable voltage with the same code and see what you get. Bob
  14. BobK

    What are these 2 "extra" red wires for? Li-Ion RC Battery

    If the likes of Apple, Samsung, and Boeing cannot charge Lithium Ion batteries without setting them on fire, what makes you think you can? Bob
  15. BobK

    Fixing Technics Speaker

    Try a different input to find out whether it is the tuner or the amp. If you are hearing static on the speakers, I would guess the tuner is the problem. Bob
  16. BobK

    Function and their types

    I think I see what your problem is with functions with a return value and no arguments. You are trying to make it return something different each time it is called, but not succeeding. Here it how it can be done: int count = 0; int counter() { count++; return count; } int main() {...
  17. BobK

    Power supply !!

    Maybe the have not allowed any new schematics in the country since they became independent. Bob
  18. BobK

    Function and their types

    I cannot even imagine what it is you are not understanding. A function with no return value does not have a return value. So we call it like this: void delay(); ... delay(); If it had a return value, we could assign to to a variable of the same type: int delay(); ... int x; x = delay()...
  19. BobK

    Pulse Width Modulation

    The problem is that the motor negative is connected to ground though the motor's houing. The PWM controller you are trying to use has to go between the ground of the motor and the circuit ground, which you cannot since the motor's ground is already connected to the chassis through it's housing...
  20. BobK

    Old Style Op Amp

    He is calling a voltage follower an op amp. Bob
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