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  1. BobK

    [newbie] Powering car horn?

    Maybe you could pull a trailer with your batteries and equipment on it. Bob
  2. BobK

    [newbie] Powering car horn?

    Here you go. Just pump it up and blast away! http://www.amazon.com/Delta-Cycle-Airzound-Bike-Horn/dp/B000ACAMJC Bob
  3. BobK

    Which PicBasic Software To Use?

    That would be a good idea too. There are some time critical things that are better done in ASM on PICs. I do most of my programming in ASM for 8-bit PICS, have only used C for 16-bit ones. Bob
  4. BobK

    how it works, how to calculate the output

    No, if you want an adjustable regulator they are available. LM317 is a popular one. Bob
  5. BobK

    Simple NPN transistor circuit

    Conventional current flows from positive to negative. Some people use electron current, which flows the opposite direction because electrons are negative. The arrow on the bipolar transistor symbol indicates the direction of flow of conventional current. Bob
  6. BobK

    Decoder to 7 seg

    You are talking about LCD and then about a 7-segment and current limiters. Which are you using? What decoder chip? Bob
  7. BobK

    how it works, how to calculate the output

    To calculate the output, read the marking on the part. Bob
  8. BobK

    Threshold Circuit - Warning - I know practically nothing about building circuits

    This can be accomplished with a comparator. It compares two voltages its output depends on which is higher than the other. You feed it a reference voltage (the threshold) and the voltage to be compared. If you have a regulated supply, the reference can be as simple as a voltage divider (two...
  9. BobK

    wireless receiver transmitter setup

    Well, with no information about it, I don't see how anyone can help. Bob
  10. BobK

    Dimming a 12V 24W Incandescent Bulb

    A potentiometer or rheostat would dissipate a large amount of power in that application. You would be better off using PWM (Pulse Width Modulation), which basically turns the current on and off rapidly and the brightness will depend on what percent of the time it is on. You can buy PWM...
  11. BobK

    Which PicBasic Software To Use?

    I would suggest switching to C. Bob
  12. BobK

    relay not working in comparator circuit

    A '741 can provide at least 10mA of current. The PN2222 has a minimum gain of 40 at up to 500mA collector current. So it would be borderline. Realistically, you are going to get only about 5V out at 10mA of the 741 off a single 9V supply. So, the base resistor calculation is: V = I R (5...
  13. BobK

    wireless receiver transmitter setup

    A link to a datasheet might help us answer. Bob
  14. BobK

    LED fixture build help

    +1 on the constant current supply. For that kind of current, a simple resistor is not a good solution. They are not really all that expensive. Bob
  15. BobK

    relay not working in comparator circuit

    You probably need to lower the 10K base resistor as well. How much current does the relay coil take? Bob
  16. BobK

    Triangulate

    Two sensors could triangulate an object if is it known to be in a given area. The second position Dave mentioned could be out made to be out of the area. Bob
  17. BobK

    HELP: Need circuit for high current control based on analogue voltage

    Sorry about the implication, but we do get such nuts here. Yes, you coil might be much less then 1H for that purpose if the mirror and magnet are small. But you will definitely have to take inductance into effect. Bob
  18. BobK

    HELP: Need circuit for high current control based on analogue voltage

    In a 1H coil, you could only change the current by 100uA per applied Volt in the period of a 10KHz signal. To put 1A through it with a 10KHz sine wave would require 62,832 Volts. What are you trying to do? It this some alternative healing device? Bob
  19. BobK

    Automatic battery charging circuit

    I guess you missed this in the first paragraph of the datasheet: Bob
  20. BobK

    HELP: Need circuit for high current control based on analogue voltage

    How fast are you talkiing about? You do know that an electromagnet coil will have a high inductance, and therefore, the current cannot change rapidly? Actaully, I should say that it requires a very high voltage to make the current change rapidly. Let's say the coil is 1 Henry, which I thik...
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