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  1. dave9

    RCA boombox

    Possibly. Open it up and play some audio, measuring whether there is AC voltage on the speaker wires, similar voltage to the left side. If there is, the speaker is probably blown. If there is not, you can trace the audio circuit backwards from the speaker, measuring for the AC signal, where...
  2. dave9

    Sump pump backup

    One of the more common problems with sump pump failure (besides the AC mains being off) is the pump itself has an on/off switch failure. This makes it useful to have a 2nd pump as a redundant measure and that pump being DC, battery powered, kills two birds with one stone. The weak link in that...
  3. dave9

    Making a Bench Top Power Supply From a 24 Volt 5 Amp Battery Charger

    Yeah there are too many variables here on how it senses and terminates charge to know if it's viable. However while we're on this topic I recently came across a new buck regulator design (meaning PCB layout) that was *new to me* in the realm of cheap *junk* coming from China. Most of the cheap...
  4. dave9

    Car horn as speaker for musical keyboard

    lol, depending on the car horn design, sure it's possible. Now you need to provide the specifics you should have in the first place. Wait, you mean just a simple stock horn? No in that case you'd want a PA-style speaker in its place. So it's do-able but you need the PA speaker.
  5. dave9

    5v Bluetooth Audio Receiver Overheat Issues

    That's all she wrote. You let the magic smoke out and need a new module. However your post was sorely lacking relevant info such as what module, what is this Great Scott project, etc. Some day the internet will invent a way to post links to things but until then, you'll have to use ASCII...
  6. dave9

    Designing a complete active speaker box

    Is it hard for you to source or afford parts? I ask because this seems like a bad ratio of effort to outcome, that this isn't going to be a result worth the effort if someone has the resources to do it a different way. Makes little sense to go to the trouble of tri-amping those poor little...
  7. dave9

    Carpet Cleaner Circuit / Transformer

    I doubt this is an elaborate setup. You pictured a transformer. Measure whether there is the rated voltage coming out of it. I'm skeptical that they even went tot he trouble of a full bridge rectifier and capacitor, but you can look and see what is there. If the transformer is not outputting...
  8. dave9

    Anyone familiar with pendulum clock mechanisms ?

    Repaired one for my aunt recently. Yes it has to be started by hand to reliably start. If it is working and you don't do that, it might eventually gain enough momentum but I wouldn't trust that, swing it to one end of travel to see what happens next.
  9. dave9

    Yamaha RX-371/3064 Amplifier Problem

    I would suspect that there is a break in the circuit, bad solder joint, PCB crack, IC socket with oxidized contacts and thermal expansion improves the electrical connection. What exactly does "voltages appear to be okay" mean? You have verified the voltage input to the output transistors for...
  10. dave9

    Gas dispenser tech

    It would seem that something else is wrong if you are blowing fuses, or is this a defective design with undersized fuses and you're fitting fuses with a higher current rating? That also seems wrong given the scenario. Can't you just move out of the hazardous location a few dozen yards to do...
  11. dave9

    Easiest method to convert analog ac voltage or frequency to digital 0-5v dc?

    Considering that this circuit seems to be for a track race car, I would advise you to buy an off the shelf product that does whatever you're trying to do. I am doubtful your insurance covers homebrew mods to the braking system and one mistake in testing - even if the circuit works as intended...
  12. dave9

    Solenoid amperes ???

    Well, IF that's an accurate photo of his, it might help because I found some info on the one pictured. https://www.m.nu/vatten/brass-liquid-solenoid-valve-12v-1-2-npt
  13. dave9

    Accesorizing Solar collection

    Reconfigure the solar array to produce 25V at double current. Run through charge controller to 12V system. You're on your own making the sign.
  14. dave9

    Solenoid amperes ???

    Either find an identical looking Chinese solenoid and get the specs from that, or implement that one while connected to a bench supply capable of current limiting to see at what point the solenoid is overcome by the pressure of what it is valving, then add a little margin. On the other hand...
  15. dave9

    CreativeLabs L3800 2.1 sound system works fine for 20 minutes

    ^ I wonder if there is a switch built into the headphone jack, or added onto the end of it so when the tip of the plug is inserted it switches, and that switch is faulty.
  16. dave9

    Help needed on portable battery project

    It's been a long time since I tore apart a hair dryer, but aren't most of the cheaper ones just a brushed DC motor with a rectifier in series? If so then you don't need an inverter but the remaining question would be how much airflow you need since that's still a heck of a lot of AA batteries...
  17. dave9

    7 x 120mm PC Fan (No LED) + 1 x LED Strip (Flashing) = 12V DC / 3.0 A Power Supply

    Try powering only one fan and measuring current consumption, then repeat measuring only the LED strip. Next calculate what the sum current of all things powered simultaneously would be. Next you can progressively add more things in parallel to see if the PSU can maintain high enough voltage...
  18. dave9

    Switching power supply emission the electromagnetic waves

    If it is not a known good quality PSU design then I would replace the PSU now, before it fails and takes other components with it.
  19. dave9

    CreativeLabs L3800 2.1 sound system works fine for 20 minutes

    It is possible you could have transistors leaking as they heat up, but I would wonder if it even has any discrete transistors in it, or just chipamp ICs? It might help if you can find a schematic. It seems to be a bi-amped design so it is possible the amp stage for bass could keep working...
  20. dave9

    7 x 120mm PC Fan (No LED) + 1 x LED Strip (Flashing) = 12V DC / 3.0 A Power Supply

    What do you mean by "in series"? Consider each fan one component and the LED strip the other component. Each component should be in parallel with the other components, nothing should be in series except the LEDs on the strip in series with other LEDs, if/as already manufactured for 12V...
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