Search results

  1. K

    Getting Decimal value instead of hex

    Fixed a typo in 10_times below: 10_times(int x) { return x<<3 + x<<1; /* x<<3 = x*8, x<<1 = x*2 */ } 100_times(int x) { return 10_times(x)*10_times(x) } You can also use macros (#define ...) to avoid the subroutine call and generate inline code instead.
  2. K

    Mini hi-fi Sony FH-B411 cd player won't play music, but tray works perfectly

    Check the ribbon cables going to/from the CD transport to the main boards, and also the ribbon cable connecting the optical assembly. These can get oxidation on them, leading to flaky connections. I've seen this on some Sony consumer gear and cleaning/reseating them usually fixes the problem. :)
  3. K

    If the source voltage is the same as LED voltage, is a resistor necessary?

    Correct. In parallel giving each LED its own resistor, or in series with a single resistor. Series wiring only works if the supply voltage is greater than the sum of the forward voltage drops of the LEDs. So a red and blue in series will likely need at least a 6 volt supply to drive them...
  4. K

    If the source voltage is the same as LED voltage, is a resistor necessary?

    Another thing to consider with those cheap LED keychains, throwies, etc. is that they're usually powered by a small button or coin battery that has a (relatively) high internal resistance. Therefore, the battery itself acts as the resistor. Also, the battery's voltage is close to the Vf of the...
  5. K

    555 to Power a Solenoid

    Put the diode across the solenoid coil, reverse biased (cathode on + side of coil and anode on - side).
  6. K

    LED viewing angles?

    It diffuses the light, sending it off in different directions. It's similar in premise to the frosted coating on the inside of a light bulb, gives a more uniform light than a clear light bulb.
  7. K

    LEDs - am I doing something wrong???

    The OP didn't say if it was a piezo buzzer or not. If it's an electromechanical buzzer, it's putting all sorts of spikes into the LED while buzzing as well as when it's shut off. Adding a diode in inverse parallel with the buzzer should do the trick. A piezo element could conceivably generate...
  8. K

    Fast, high current switching

    If the zener is getting hot, it's shunting a lot of current. This means the zener's voltage is lower than your supply voltage. If the pin 1&2 voltage is 10.7V, that's probably a 10-11V zener diode. You want one that's higher than the peak output voltage of your supply voltage, since it only...
  9. K

    Why does my op amp sink/source current?

    Did the same thing happen when you prototyped the circuit? If not, maybe there's an error in your PCB, or a slight short causing a current leak. If it happened in the prototype as well, it could be current through R6 and R4 to ground. What voltage is the supply to the LED positive lead? If...
  10. K

    Voyager Space Probe distance counter

    Unfortunately work leaves me with almost no time to pursue anything hobby related, so I wouldn't be able to take on this project, sorry. I can offer suggestions on the forum, that's about the best I can do, without a winning lottery ticket. A mid-range PIC should work, especially if serial LED...
  11. K

    Voyager Space Probe distance counter

    For #2, provide enough digits to cover the distance for the foreseeable future. You're going to need to know the current distance and speed to calculate the distances, so do the math and figure out how far it would be in say, 20 years and provide enough digits for that. If that's more digits...
  12. K

    Why Use A Business Telephone System For Your Business?

    Spam??? o_O
  13. K

    Keyboard Ribbon Cable Repair

    You can put Kapton high-temperature tape over the plastic part to keep it from melting. If you're replacing the connector anyway, it would be a good test with the old one to see if it is heat resistant or not.
  14. K

    I have a Bose Lifestyle 28 Acoustimass module needs repair.

    Maybe pry the bar off? Is it wood or metal? Can you post a pic?
  15. K

    I have a Bose Lifestyle 28 Acoustimass module needs repair.

    Bose has good customer support, give them a call, they'll probably take care of it for you. Unless it's really old and out of warranty. Is it the bass module or one of the satellites? I think the grills pop off on the satellites and you can get the speaker out that way. Don't know where you...
  16. K

    I'm back - a new circuit for the mini-golf course

    It's hard to know how old the setup is, as BASIC Stamps have existed since the 1990s are are still made today. So, it could be 20 years old, or just a few years. But the added music and lights at the hole explains why they used a microcontroller in the first place. The flashing lights and...
  17. K

    I'm back - a new circuit for the mini-golf course

    Here's a quick schematic I drew up. It's not the neatest but it gets the point across. Q1 amplifies the signal from the phototransistor and energizes the relay. Once it's energized, the contacts ground out the circuit so that the buzzer and LED stay lit until momentary normally-closed button...
  18. K

    I'm back - a new circuit for the mini-golf course

    BASIC Stamp..OMG! That was the first microcontroller I ever played with. I have one of those development boards kicking around. For what the circuit does, it's huge overkill (unless it does other things besides just sound a buzzer when someone sinks a hole on the 19th). A latching relay will...
  19. K

    I'm back - a new circuit for the mini-golf course

    It's possible that the phototransistor circuit won't have enough current to energize the relay by itself (looking at your other thread, it has a 10k resistor). You'll probably need a transistor to amplify the current at the clubhouse end. I'll be out all day but can post a schematic later, or...
  20. K

    I'm back - a new circuit for the mini-golf course

    A relay with a 12v coil and SPST or SPDT contacts is fine. It doesn't have to be heavy duty or anything, just enough to power the buzzer and the relay coil, so even a small relay with 1 amp contacts will be plenty.
Top