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  1. KrisBlueNZ

    Serial port mouse to USB mouse

    Not without a ridiculous amount of effort. Original serial mice are relatively dumb. They generate a stream of serial data in the form of bursts of characters that can be received by an RS-232 serial port and interpreted by the driver. USB is a bidirectional protocol that requires intelligence...
  2. KrisBlueNZ

    Beginner question: diodes?

    As others have pointed out, you can't connect the potentiometer in the ground lead of the headphones. This will cause the problem you describe, where the sound becomes thin and disembodied. This is not just because you only hear the sounds that are far from the middle, it's also because you hear...
  3. KrisBlueNZ

    Remote Distance Sensing

    Is this indoors? If not, any wind will screw things up big time. I think it's appropriate, at this point in the thread, to ask the OP WHAT DO YOU WANT TO DO? You've said you want to "know how far you are from a starting point". This doesn't tell us very much. Would you care to explain your...
  4. KrisBlueNZ

    Voltage limiting without altering waveform

    Well, the output is DC-coupled to the sound card input, if that's what you mean. The input is AC-coupled and the op-amp is acting as a buffer, so there will not be any (significant) DC on its output.
  5. KrisBlueNZ

    Passing signals with no current.

    As Dave and Steve have already pointed out, there will be SOME current flow, even if it's just a few microamps. AFAIK, low-current gold-plated connectors, switches, and relay contacts don't have minimum wetting current requirements, because gold doesn't oxidise. AFAIK. These requirements are...
  6. KrisBlueNZ

    frequency divider

    What do you mean by "TR level circuit"?
  7. KrisBlueNZ

    anolog vom repair

    You might find it better to use an 82 ohm 1% resistor in series with a 20 ohm trimpot. That will make it easier to adjust exactly, and will prevent you from accidentally turning it all the way to zero ohms.
  8. KrisBlueNZ

    Computer Power Unit Failure

    If you can get the STF25NM60ND then yes, I would use it instead of the STF34NM60ND that I suggested. The STF25NM60ND is an "FDmesh II" device, compared to the original which is "MDmesh II". (In my previous post, I originally said that the original MOSFET was "FDmesh" but that's wrong; the...
  9. KrisBlueNZ

    Voltage limiting without altering waveform

    Good. The x100 probe is probably designed to work with a measuring device that has a specific input impedance. Check the manual for the probe. Where did you get that idea? They should be normal bipolar transistors. They only need to be rated for 100 mA and 30V. They should have fairly high gain...
  10. KrisBlueNZ

    12v LED Strobe Controller

    Well, feel free to make him an offer :-)
  11. KrisBlueNZ

    Computer Power Unit Failure

    The specifications of the original STF25NM60N are: STMicroelectronics "MDmesh II" N-channel MOSFET Vds(max) = 600V Id(max) = 21A Rds(max) = 160 mohm @Id=10.5A and Vds=10V Gate capacitance 2.4nF @Vds=50V Power dissipation = 40W Package = 220FP (fully insulated) It seems it's no longer...
  12. KrisBlueNZ

    stereo amplifier

    Great! I guess, with a fast-blow fuse. The main reason would be to protect the shaker against a fault in the amplifier (or the signal generator that feeds it). Personally what I would do is this. Put a fuse in series with the feed from the amplifier to the shaker. Start with a 1A fuse. (Always...
  13. KrisBlueNZ

    How to add a Li-Ion charging circuit to board design

    You can get ICs specifically designed to control the charging of Li-ion batteries (and other chemistries). These will give best performance and safety. A quick search on Mouser shows that battery charge controllers are made by Microchip (www.microchip.com), Texas Instruments (www.ti.com), Maxim...
  14. KrisBlueNZ

    new to circuits ?

    Right. Most modern, mass-produced electronic products use SMT (surface-mount technology). THT (through-hole technology) is mostly limited to hobbyists and some ultra-budget Chinese stuff. Why are you so interested in the idea of modifying these pedals? They're generally pretty well-designed and...
  15. KrisBlueNZ

    Voltage limiting without altering waveform

    I've made a few more improvements. Here's an updated schematic. Please throw out the earlier schematics. I've changed the op-amp supply rail and protection circuitry to completely prevent any back-feeding of input overload voltage into the sound card's supply rails. I've changed the...
  16. KrisBlueNZ

    new to circuits ?

    Are you sure it's "458"? If it's 4558, that is a standard component called a "dual op-amp". It's totally analogue. Simple pedals like fuzz/distortion, wah-wah, filtering and so on are normally analogue, unless they're very high-tech (and expensive), in which case the processing could be done...
  17. KrisBlueNZ

    Voltage limiting without altering waveform

    Q1 and Q2, no. The others, yes, but with circuit changes. I suggest you get some transistors! They can be pretty useful. You may be able to find a bulk pack with a selection of NPN and PNP small-signal transistors. I've just noticed an error. D1 and D2, the zeners across the power supply rails...
  18. KrisBlueNZ

    12v LED Strobe Controller

    KJ6EAD, thanks for your suggestion. I'm surprised to hear that the negative connection is sometimes internally connected to the mounting flange on these units. I guess if that's the case, the LED pods will all illuminate constantly, and he will know there's a problem. In this case, where his...
  19. KrisBlueNZ

    12v LED Strobe Controller

    Right. I've shown it as a trimpot, or "preset potentiometer", which you adjust with a screwdriver. But you can also use a potentiometer with a knob. Yes, it's a bit simpler. The differences are: 1. Circuit #1 flashes the LEDs FOUR times on each side; circuit #2 flashes them THREE times on each...
  20. KrisBlueNZ

    12v LED Strobe Controller

    Here's a design for you to look at. I've split it up into modules. Starting at the top right corner is the DC input conditioning circuit. You will need one of these to clean up the 12V supply from the vehicle, which can have interference and large surges on it, which can cause misoperation...
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