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  1. KrisBlueNZ

    12V - 350V 200mA converter for motorcycle CDI

    No, if the core was saturating on every switching cycle, the MOSFET would run warm at least. It might be saturating during the early part of each charge cycle. But you should make sure that it can't, by design. Which means you need to know the actual saturation current. Have you been testing it...
  2. KrisBlueNZ

    decoder for 8051

    Program memory address bus - 8 bits (PA0~7); Program memory data bus - 4 bits (PD0~3); Program memory read enable; Register memory address bus - 2 bits (RA0,1); Register memory data bus - 4 bits (RD0~3); Register memory read enable; Register memory write enable.
  3. KrisBlueNZ

    decoder for 8051

    You can't address 32 registers if your instruction word only has a 4-bit register specification. That was an example that I created because you said you wanted a 16-bit-wide instruction word. I divided those 16 bits into a 6-bit opcode, a 5-bit source register number, and a 5-bit destination...
  4. KrisBlueNZ

    12V - 350V 200mA converter for motorcycle CDI

    OK, I'm dredging back quite a few years here. If anyone spots a mistake here, please say so! Normally, the manufacturer gives you full specifications. These include µr (relative permeability, a dimensionless quantity), AL ("inductance amplification" in nH/turn2), le (effective length), and Bsat...
  5. KrisBlueNZ

    decoder for 8051

    I don't know what the code or the instruction examples mean. I understand that you have an 8-bit instruction word, divided into a 4-bit opcode and a 4-bit register specification. The ALU has an accumulator, which is the "other" register for all two-register operations, and the destination...
  6. KrisBlueNZ

    12V - 350V 200mA converter for motorcycle CDI

    The diagram looks good to me. I can't comment on the ferrite former without knowing its specifications. It's easy to check for core saturation in that circuit - just put a scope across the source resistor.
  7. KrisBlueNZ

    Capacitive Reactance Circuit

    Well, I tried adding a 47 nF capacitor from point B to Neutral and it made hardly any difference to the peak current through the bridge diodes when a disturbance is applied. I don't know why, but I trust LTSpice. (Not necessarily in all cases, but in this case, I trust it.) My disturbance was a...
  8. KrisBlueNZ

    Capacitive Reactance Circuit

    Cool. No problem. But I should have mentioned that the "design 2", which has no smoothing capacitor and no series resistor, exposes the LED to potential overcurrent during input disturbances. Design 3, with the large smoothing capacitor 3CS and the 3RS series resistor, will do a much better job...
  9. KrisBlueNZ

    Promote a post!

    hevans1944 describes how to measure electrolytics by timing their discharge to 37% of their initial voltage using a known resistor value: https://www.electronicspoint.com/threads/testing-capacitors.270946/#post-1628042
  10. KrisBlueNZ

    decoder for 8051

    A 16-bit-wide instruction opcode can specify 65536 different instructions. No processor needs that many distinctly different instructions, so the instruction word is generally divided into bitfields. For example, there might be a single instruction to copy the contents of one register to...
  11. KrisBlueNZ

    ATX PSU Power Toggle Circuit

    I'd use 10k resistors for R3 and R4, as well as R1, just to shorten the BOM. And to save a bit of current, in the case of R4. You don't need to provide much base current to Q1; it is not driving a heavy load. That allows you to reduce C2 to 1 µF or less (0.47 µF for example), so you could use...
  12. KrisBlueNZ

    Capacitive Reactance Circuit

    OK, here are two variations on the capacitor-fed power supply. Both of them use bridge rectifiers. I've specified a 330Ω 1/3W or 1/2W fusible resistor for Rin. This is a good compromise between power dissipated during normal operation (which must be comfortably less than the resistor's rated...
  13. KrisBlueNZ

    Capacitive Reactance Circuit

    The waveforms in post #1 are 180° out from each other - the positive peak on the voltage lines up with the negative peak on the current. This happens if the resistor is "connected backwards". Normally that's a meaningless concept for a resistor, but in LTSpice a resistor has two specific...
  14. KrisBlueNZ

    Use diode to attach multiple circuits

    Mr. Einstein, we (the moderators) want to make sure you know that transmitting without a license, and especially jamming other transmissions, may be illegal and could get you fined or prosecuted. It's not difficult for authorities to locate a transmitter. Also, like other illegal activities...
  15. KrisBlueNZ

    Finding full load amperage

    A wristwatch? That needs to be recharged every month? What's the make and model number?
  16. KrisBlueNZ

    Red seven segment led display

    You're welcome :-) The driver supplies positive voltage to the segments. The display is a common cathode type, and the common cathode terminal is connected to the 0V rail. So to turn segment C ON, the MSM561 driver drives pin 13 high (probably to +5V from the +5V rail). This causes current to...
  17. KrisBlueNZ

    Hello

    Hi Nathan and welcome to Electronics Point :-)
  18. KrisBlueNZ

    Capacitive Reactance Circuit

    This is the voltage across R1, and the current through it? I think you must have made a mistake somewhere. R1 is just a resistor; the current and voltage are proportional at any instant in time (ignoring parasitic effects, which aren't significant at 60 Hz). Noise or ripple? If it's ripple...
  19. KrisBlueNZ

    Random PICAXE Output for 4026

    You want your roulette wheel to use seven-segment LED displays? Yes you could do that. You would need two control signals. One to reset all of the 4026es, and one to clock the first one, with the others cascaded from that. The PICAXE would reset them to start the count at zero, then clock them...
  20. KrisBlueNZ

    What does the symbol imply?

    I've seen the other thread and I don't have anything to add.
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