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  1. K

    CD player leaving powdery residue on CDs

    Open them up and take a look inside. If you have any moisture issues (i.e. CD player is near a window or AC vent) it could be mold growth or something.
  2. K

    CD songs distorted badly first two or three songs.

    There's more than one way the laser lens moves. First of all, the lens itself can move up and down (to focus the beam), and laterally (in and out) to track the data spiral on the disc. This is done using a mechanism that lets the lens "float" and be moved precisely and quickly using...
  3. K

    CD songs distorted badly first two or three songs.

    Sometimes those older Sony boombox CD players develop oxidation on the connections between the main board and the laser pickup. Try opening it up and disconnecting and reconnecting the ribbon cables and see if that helps. Since it's occurring more on the first few tracks, it could also have a...
  4. K

    Creating 1.12v ac at 22.5khz

    1.12V isn't really accurate. The controller is generating AC pulses that your meter is probably misreading due to the duty cycle and pulse shape. More likely it's 3.5-ish volts to get the LEDs to light at all. It's alternating the polarity (generating highish frequency AC) to make all the...
  5. K

    Need recommendations for button/switch, springy and loud

    If you can't find a suitably clicky button you could always wire it to trigger a loud clicky relay or solenoid to make the sound.
  6. K

    I cant measure voltage on 100 picofarad capacitors on multimeter

    Some multimeters have a capacitance measurement setting, and maybe also ESR and leakage. If you're going to be making capacitors, I'd get a meter that can measure them properly. Measuring charge voltage on a small capacitor isn't going to tell you much, other than that it can hold a charge at...
  7. K

    Need help with DC Dimming seven seg displays.

    The gist of that circuit is that the LED gets brighter when less light hits the photocell. Probably not what the OP wanted with his 7 segment displays... he probably wants them dimmer when it's dark, which could be done with that circuit by swapping the photocell and resistor in the circuit...
  8. K

    Need help with DC Dimming seven seg displays.

    Another thing I just realized (these things keep popping out)... Vss is usually ground or the negative rail, while the positive rail is marked Vdd or Vcc. Vss and Vdd are voltage to source and drain of an N channel MOSFET; Vcc is the voltage to the collector of an NPN transistor. But, until...
  9. K

    Need help with DC Dimming seven seg displays.

    Good catch. There's other issues with the schematic when taking a closer look (it's hard to follow all those red lines going everywhere!). The common pins on the displays are connected to the collectors of the transistors but also to the +5V rail. Also, the emitters of the PNPs are connected...
  10. K

    Need help with DC Dimming seven seg displays.

    What is this display going to be used for? You have a circuit for a multiplexed 5 digit 7 segment display, but it's not connected to anything. Normally you wouldn't dim these linearly since you would have to have a dimming circuit for each of the 7 segments (where your 220Ω resistors are now)...
  11. K

    Need help with DC Dimming seven seg displays.

    What's driving the display now? A microcontroller? Are you writing the firmware? Dimming of displays is usually handled via PWM. With a multiplexed display, you could change the pulse width of either the row or column outputs to control the overall brightness of the LED displays. There are...
  12. K

    Toggle between 2 LEDs on separate circuits in the same circuit?

    Make sure the resistors are only in series with the LEDs and not the relays or fans. Can you post a full schematic including where the relays are connected?
  13. K

    Adding a trim pot to a fan motor

    The pellet stove fan had a speed controller of some sort, and the pot just controlled the controller. A small current through the pot (or voltage coming out if the pot was wired as a voltage divider) told the controller how fast to run the fan, using some form of PWM similar to a dimmer switch...
  14. K

    powering 2 LEDS or Neons from a 240v feed?

    So if the dial light burned out the whole radio would stop working. Brings a new meaning to "one light goes out, they all go out!"
  15. K

    I received a message of crystal diskinfo hdd

    You'd have to use a hashing tool like md5sum or sha2sum (latter is more robust) to generate hashes of the files before and after moving them. If the hashes are the same the file is ok. As I mentioned before, the ECC in the drives will largely prevent files from being silently corrupted, but...
  16. K

    I received a message of crystal diskinfo hdd

    According to the Wikipedia article, S.M.A.R.T. was introduced in 2004. Prior to that, it's possible that some manufacturers offered bad sector reallocation in their drives, but it would have been internal and not reported to the end user, or reported through some proprietary method rather than...
  17. K

    I received a message of crystal diskinfo hdd

    Hard drives use ECC codes to not only detect bad sectors but to correct minor errors and detect/report more serious ones. It's not very common for a drive to return corrupted data; if the data is in a bad sector and the ECC can't correct the error and retries can't get it to read, you just...
  18. K

    powering 2 LEDS or Neons from a 240v feed?

    Encouragely discouraged? Discouraged to be encouraged? I would say, "not a good idea for safety reasons". :) In any case, I'd avoid neons for this application, they just won't look good, plus you'd have to run HV to the bulb locations. There should already be low voltage (6 or 12V) to the...
  19. K

    powering 2 LEDS or Neons from a 240v feed?

    Most old radios used small incandescent bulbs to illuminate the dials. If you want the most authentic look, that would be the way to go. Are the original bulb sockets and circuits intact? You'll just need bulb(s) of the correct voltage and size to fit in the sockets. Chances are they're fed...
  20. K

    Identifying input polarity

    Maybe try a forum... or ask someone that had one installed to see where the wires are connected. Nothing like saying "we only allow professional installation" so they can charge more, and then refuse to provide any information on the product to aid in installation, or troubleshooting for that...
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