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  1. BGB

    motor driving: sane?...

    so, had been working on boards to drive a motor. one is a triple half-bridge, with 12x MJE3055Ts, in turn driven with 3x TIP122 or TIP127 transistors. two 3055Ts are naively wired in parallel, which is theoretically a terrible way to do it, but in past tests it doesn't seem to blow up. this is...
  2. BGB

    back for now: PWM + Serial (single wire)

    earlier, I wrote some code (for an MSP430) for implementing a 3 phase VFD, using both servo-style PWM and I2C for control inputs. then I was thinking, it is a little pointless, as the I2C and PWM are both partially redundant and also one ends up with the worst of both worlds. so, I had an idle...
  3. BGB

    idle: driving steppers closed-loop?

    ok, so this is one of several ideas that I have been thinking of recently. so, goal is to drive a stepper closed loop (similar to what can be done with a BLDC motor), preferably without any reliance on external sensors (IOW: preferably no encoders or similar), and ideally without modifying the...
  4. BGB

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

    this is one of those ideas that keeps popping up (mostly in the context of robotics use-cases). I am mostly interested on opinions, or if such a thing could be technically / economically feasible. ADD: well, they basically exist, but are generally crazy expensive, so it is more a question of...
  5. BGB

    induction...

    some recent observations imply my understanding of induction seems weak. at first, I used some smaller diodes in a circuit, expecting the current from the inductive flyback to to be small relative to that driving the load (say, one drives 1A into a coil, maybe seeing 50 or 100mA going back up...
  6. BGB

    OT? Volt/Amp/Watt fundamentals (and simulator issues).

    in my electronics-simulator sub-project, stuff seemed to be ok when it only had wires. I could make wires, and short things between Vcc and Gnd, and saw plausible looking voltage drops and amperage values. then went and added resistors, which sort of work, but a bit of problem emerges: current...
  7. BGB

    side: better simulators?...

    well, for a while I have been using LTspice, and it basically works, however: I would like to be able to run and tweak circuits in real time (or interactive sub-real-time, say, 1000x slower than real-time), and don't like having to manually re-simulate; I would like something that doesn't freeze...
  8. BGB

    fried L298N, stepper motor fun...

    well, back to this (after a good long while). my past attempts at current limiting the L298N (with improvised analog electronics) were ultimately not successful, and eventually the thing fried. couldn't really get accurate current limiting, and the stepper kept trying to pull more current than...
  9. BGB

    projects: testing this out...

    BGB submitted a new Showcase Item: projects: testing this out... Read more about this showcase item here...
  10. BGB

    idle: yet another current-limiting scenario...

    ok, here is the scenario this time: I am still using ADRS-550SH motors, for another thing this time. some stats for the motors: Operating voltage: 3-16V No load speed (min.): 19,000rpm No load current: 1.4A Stall current*: 74A Max. efficiency current: 10A Max. efficiency...
  11. BGB

    battery powered device, reviving some old UPS batteries...

    well, I am building a battery powered device (a small/modest-sized rolling robot, around 15x17 inches, or 30x34cm, with mostly cardboard construction), seemingly relatively low power (around 10A max), and had a few old/used UPS batteries (lead-acid, 7.0Ah, AGM/VRLA style). don't know full...
  12. BGB

    MOSFET H-bridge, weird effect...

    built an H-bridge, and something very odd happens... namely, normally, when the power is connected directly to the motor, it spins up, and when power is disconnected, the motor slows and stops over a period of around 1 second or so. similar also happens with my other H-bridges. however, when...
  13. BGB

    Current limiting strategies for L298N?...

    well, here is the issue: I am building a project (a small CNC milling machine), and for the steppers am going to be using some L298N chips. these will be driven from a Raspberry Pi, possibly with step-up transistors (data sheet seems to imply it is intended to be driven with 5v 30mA signals...
  14. BGB

    new here, H-bridge frustrations...

    ok, I am new here... and, I am relatively new to electronics as well (my main thing is mostly programming, but I have been messing a bit with electronics over the past several months). but, one thing I have noticed is an annoyance with trying to build H-bridges which work well... in...
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