Search results

  1. BGB

    misc idea: small (3-phase BLDC) motors with built-in drivers.

    errm, but you would not normally use BLDC motors for precise XYZ positioning absent some pretty significant gear reduction (say, 4000:1), and generally BLDC motors aren't very good about accurate microstepping, so the hall-effect sensor would likely be about as accurate as one can reasonably...
  2. BGB

    misc idea: small (3-phase BLDC) motors with built-in drivers.

    I have already thrown together a basic G code interpreter, and have the code for running the stepper motors and similar already written (it is basically the same basic code which is used in my other projects). G code is actually a fairly simple language. ugly yes, difficult to process, not...
  3. BGB

    misc idea: small (3-phase BLDC) motors with built-in drivers.

    yeah. you can either use things without feedback, but with BLDC motors this leads to a problem that it either runs at full speed, or it doesn't really work at all (in contrast, using an induction motor it will just run slower if under load, but you have no real idea how far an induction motor...
  4. BGB

    misc idea: small (3-phase BLDC) motors with built-in drivers.

    yeah. I had remembered once being in an RC / hobby store, then wondering what some of the parts they were selling were rated for. most were well-below what I had an immediate use for. like, a lot of things like wheels that can only handle 5 lbs, 7.2v 4.8Ah ("large" battery packs), ... NiMH...
  5. BGB

    misc idea: small (3-phase BLDC) motors with built-in drivers.

    they are "small" projects in the sense that one is dealing with loads typically around 20lbs to 40lbs, as opposed to "large" loads of say, 200lbs to 1/2 ton. if you are moving 40lbs around, and need it to move reasonably quickly, you really will need those 100 watts. typically, you would be...
  6. BGB

    Reduce amperage without reducing voltage. Diodes? [Noob]

    here is an example, so they seem to exist in any case: http://www.mouser.com/new/kingbright/kingbright-resistor-LEDs/ from the ones I had scavenged before, no external resistor was used, it was just the wires connected up directly to the LEDs (on one end, the other ends would be dupont...
  7. BGB

    Reduce amperage without reducing voltage. Diodes? [Noob]

    one thing I had noticed before, but that had come up unexpectedly, was the whole LEDs and resistance thing. previously, most of my LEDs had been ones that came out of computer front panels and similar, which you just connect up to 5v and they work, having somewhere around 1k of resistance or so...
  8. BGB

    What's the difference between copper/brass power plugs and nickel plated ones?

    could be a nickel or cadmium plating over steel, which may resemble brass (both may appear yellow), but isn't as good. as for power-strips: yeah, I wouldn't trust them with anything important. for anything important, an actual surge-suppressor or a UPS is better. a UPS will also protect...
  9. BGB

    What's the difference between copper/brass power plugs and nickel plated ones?

    AFAIK, brass is used as a special purpose conductor in some applications, mostly as it has better mechanical properties and corrosion resistance than copper and aluminum, with a modest loss of electrical conductivity (it is roughly on-par with aluminum). likewise, it is more resistant against...
  10. BGB

    Odd RasPi Behavior?

    I have a B, WiFi dongle, and a webcam, and this pulls 700mA. mouse+keyboard may pull enough power as to leave a 500mA supply not providing enough power to run the RPi's CPU or other onboard electronics.
  11. BGB

    mosfet diode

    @hevans1944 the 2N3055 looks a bit (specs wise) like the MJE3055T, just using TO-3 packaging rather than TO-220, and with a higher amperage rating. likewise, the 2N2222's I have are in the TO-92 packaging. I had also wondered about using small transistors as temperature-sensors, say, if one...
  12. BGB

    mosfet diode

    @hevans1944 yeah. I had been using some Darlingtons (TIP122 and TIP127) for driving some small steppers. seems to work ok. when I got them online, I got them for about $0.25/ea. noted that there is some variability, and have seen prices for them a bit higher as well. had tried using a L298...
  13. BGB

    mosfet diode

    yes, ok. in both cases (BJT and MOSFET), was assuming driving them using PWM, where the heating doesn't seem to be too bad for either of them (vs controlling them with analog, where serious heat results). (also the BJTs are cheaper, at least per-transistor...). went off on a tangent a bit...
  14. BGB

    mosfet diode

    I was mostly noticing that, provided that enough power is provided to fully switch them, there didn't seem to be huge difference in how hot they get between MOSFETs and BJTs (for similar amounts of amperage). however, if not enough base current is supplied to the BJT, it gets very hot fairly...
  15. BGB

    mosfet diode

    with MOSFETs and some BJTs (ones with built in diodes), I have sometimes wondered how much current they can carry relative to the rated value of the transistor. say, if you have a transistor rated for 5 amps continuous, can its diode also run 5 amps continuous?... or more, or less. the data...
  16. BGB

    HUH?????

    yeah, but no idea about output or efficiency. could be smaller and cheaper than a wind-turbine at least, and maybe good if a person's yard gets a lot of wind. could do a small-scale experiment, have an old fan, but the path to get to it (outside) is currently flooded. would also need to mount...
  17. BGB

    HUH?????

    yeah. when connected up, an alternator, as if by magic, takes a fair bit of force to turn, while a disconnected alternator can be turned relatively easily (you gently turn it, and is spins freely for a little while...). then if course, there is all the magic goes into making induction motors...
  18. BGB

    HUH?????

    possibly, but he was also saying stuff, but it didn't really make much sense to me what he was going on about... but, yeah, everything being shown was basically just stuff with magnets though.
  19. BGB

    HUH?????

    just encountered this: watched part of it, was unable to make any real sense of whatever he was going on about...
  20. BGB

    Transformer

    pretty much. you don't really want eddy currents, so laminated steel is used. too many eddy currents will cause the steel to try to turn into a magnet (strongly opposing the change of field direction, and generating considerable amounts of waste heat as the field flips back and forth). the way...
Top