Search results

Search Forums New Posts
  1. BobK

    Resistor value identification

    Green black brown would be 500Ω Black should not be allowed as the fourth band. But the fact that the 3 bands are together makes me think it is a 3 band color code. Bob
  2. BobK

    Resistor value identification

    Looks like green brown gold, which is 5.1Ω Bob
  3. BobK

    FSK project

    The 12 bit X10 code is: 4 bits house code (so your neighbor does not turn your lights on and off) 4 bits device code 4 bits command (which might be on, off, dim, brighten, and others) By a unique code, I just mean transmit 8 or more bits of data to start each message that is always the same...
  4. BobK

    FSK project

    The home automation thing is not a bad idea. You are not just sending on / off as you implied. To reject noise, you would send a unique digital signature to make sure you were seeing actual data from your transmitter. And, each device controlled would also need a unique key. X10 protocol...
  5. BobK

    FSK project

    Let's look at the data rate required for VGA. Lets take the old 640 x 480 standard with full color, 60Hz update rate. This requires 3 bytes per pixel 60 times a second. So the data rate is: 3 x 8 x 640 x 480 x 60 = 442MHz This is orders of magnitude higher than you will be able to achieve...
  6. BobK

    Stage Line 500W amp repair project

    I can think of one way to explain the readings we have been getting. If the upper side of R108 is not making contact and the lower side is shorted to the V+ supply. This would explain why there is no current through R108 and it reads 1K correctly when probed from the top. It also explains why...
  7. BobK

    D.I.Y Speakers-Tweeter Problem :-(

    A 3300uF capacitor will pass the entire audio spectrum into a 4Ω or 8Ω speaker. The -3dB point is 12Hz for a 4Ω and 6Hz for an 8Ω. This is not a useful capacitor for a tweeter crossover. So, your results are as expected. A tweeter crossover would be on the order of 10uF, depending on the...
  8. BobK

    Stage Line 500W amp repair project

    And the probes are between the leg of R108 that you removed and the pad that it normally connects to? Bob
  9. BobK

    Stage Line 500W amp repair project

    Okay! What ranges does your meter have for current, if any? Bob
  10. BobK

    Stage Line 500W amp repair project

    No, you need to be on a current range. A or mA. We are expecting around 3mA. But start on a higher range and go to lower ranges only if it reads 0 or 1 digit. Bob
  11. BobK

    Stage Line 500W amp repair project

    Adam asked you to measure current, not resistance. Or are you actually measuring current and deducing that the resistance is going up? Bob
  12. BobK

    Variable power supply for under 3 volts

    Controlling the base of a transistor via a forced voltage is a bad idea. If the transistor heats up, more current will flow, causing more heating... Use a fixed voltage (say 3V) and a pot to control the current. Use a fixed resistor in series with the pot so it cannot go too high and destroy...
  13. BobK

    Dual controlling of a Relay

    Bluejets is on the right track, but there is no need to have two pins from the Arduino to control the relay. That can be done by the software. I.e. You the Arduino reads the manual switch. If in manual mode it puts that value (0 or 1) out to the relay. If in auto mode it simply ignores the...
  14. BobK

    Stage Line 500W amp repair project

    The transistors connected to red wires you are worried about. Anyway, I looked at the schematic and they are not. Looks like part of the protection circuit. Why do you think there is something wrong concerning the red wires? Bob
  15. BobK

    Stage Line 500W amp repair project

    Are those the power transistors that you have removed? Bob
  16. BobK

    Where to find an LED counter?

    Well, you would need 3 at least, two for power and 1 for the signal to count. Bob
  17. BobK

    Need help Transistor Touch Sensor

    Unfortunately that is not so simple. The brightness and viewing angle are inversely correlated. So an LED with 10000mcd but a viewing angle of 15 degrees will look very bright, but only if you are looking straight at it. How is this LED to be used? Should the viewing angle be wide, or is a...
  18. BobK

    Variable power supply for under 3 volts

    A voltage divider is not the way to provide power. How low does it need to go? And LM317 adjustable regulator can go down to 1.25V. Bob
  19. BobK

    Stage Line 500W amp repair project

    Did the fault light go off? Bob
  20. BobK

    Yes another NEWBIE question!

    Oh, okay. You will probably have to build it yourself then with a microcontroller on the transmitter to transmit a unique code to each receiver which will also need a microcontroller to interpret the code. Bob
Top