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  1. BobK

    Keypad to dual 7-segment display circuit

    You could do that, but I was thinking of using a serial interface between the two boards, and each display could show the number entered on both keypads on its 4 digits. You are going to need to program the PIC anyway. Bob
  2. BobK

    IR sensor

    How about a link to the sensor? If you are talking about an IR remote control sensor, they work by looking for a specific frequency (the carrier frequency, usually about 38KHz). They have a logic output that indicates that the carrier is dectected. Information is then transmitted serially...
  3. BobK

    Prefered: Undervolt or Overvolt a circuit?

    Okay, you might get by then with a current draw well below the rating of the power supply. Bob
  4. BobK

    Prefered: Undervolt or Overvolt a circuit?

    You are also not likely to get more than 10V from an LM317 with input of 12V. Bob
  5. BobK

    Keypad to dual 7-segment display circuit

    Here is a pretty cheap development board that has what you need, 4 digits and a keypad. You would additoanlly need a programmer like PICKit 2. The development tools can all be had for free from Microchip. All the harware would run about $100...
  6. BobK

    Keypad to dual 7-segment display circuit

    I would do this with a micro on each side and serial line between them. You would build two identical boards with the micro, keypad and display. Since you are not experienced with micros, it might be easier to look for a development board that is already set up with a keypad and display...
  7. BobK

    Is this Amount of Wattage Correct?

    What are you not getting? If it states 230V why would you think it runs at any other voltage? It is possible, (though not likely) that a transformer is used and the motor runs at a lower voltage, but I would not assume that unless I took it apart and found that configuration. Bob
  8. BobK

    Looking For A Low RPM <30rpm Motor

    What you need a 30 RPM gear motor. Look it up on google. Bob
  9. BobK

    Measure water in soil

    Did you try google? Bob
  10. BobK

    Valve (tube) amplifier schematic help

    If that is a bridge rectifier and two resistors, you are wasting about 97% of the power. A single capacitor and the two LEDs would also work, wasting no power. Bob
  11. BobK

    Lighting help needed

    Power (measured in Watts) is the product of voltage and current, so: 12V times 1.6A = 19.2W Bob
  12. BobK

    1N4007 question

    Unless it is a constant current supply, which he did mention in the OP. Bob
  13. BobK

    Help regarding line follower ?

    Pretty much any microcontroller could be used. Google is your friend. Bob
  14. BobK

    Need some help with LTC4425

    Another question, what is your experience? This chip is a surface mount chip with a thermal pad that must be soldered to a ground plane of a PC board, which pretty much means that it must be soldered by reflowing. If you did not understand any of that, you probably cannot use this chip. Bob
  15. BobK

    Need some help with LTC4425

    Explain more about what you are trying to do. The purpose of this chip is to charge up a couple of supercapacitors so that they can provide more current in a short burst than the battery or power supply can supply. Is this what you want? If so, choose the sample application circuit closest to...
  16. BobK

    Need some help with LTC4425

    It is all in the datasheet. You program the voltage to charge to with this equation: VOUT = VFB • (1 + RFB1/RFB2) where VFB is 1.2V. i.e. divide Vout by 1.2 to get the ration to make the Rfb1 Rfb2 divider. Example: To charge to 3.6V use a divider that will divide the voltage by 3...
  17. BobK

    Rectifier circuit fails when capped.

    Actually, I don't think is it necessary. The two capacitors will divide the voltage equally as long as they are the same capacitance. Bob
  18. BobK

    Where to find electronic experts

    And if you actually have a viable "value added" feature, it would be better to do this with software rather than creating a whole new hardware platform. Bob
  19. BobK

    1N4007 question

    You are correct to isolate the two drivers with diodes. Do use a diode that is rated for more than the current you expect to go though it. If you want less heating, use shottky diodes, they have a lower voltage drop and will therefore not heat up as much, or waste as much power. Bob
  20. BobK

    1N4007 question

    What is a little warm? Warm to touch, but you can leave your finger on it without burning it? If so, that is perfectly okay. If you want to dissapate less power in the diode, using a higher current diode will not help, though if it is phyically larger it might get less warm. To reduce the...
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