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  1. Old Steve

    I need help locating something to measure current on a circuit and relay that via bluetooth.

    I'm amazed that they don't cook, at such a tiny size, (2.62mm x 2.14mm), and running at 26MHz. I suppose they're intended to be attached to something that would serve as a heatsink.
  2. Old Steve

    How to time a watch winder

    Have you built the entire circuit, or just the 555 stage?
  3. Old Steve

    How to time a watch winder

    Those caps go from +V to ground. (That's what the little symbol means at the bottom of the caps, the same as the ground connections on C1, the 4013, the 555 and the transistors. I expected that you'd need to do some fine-tuning. That's due to capacitor leakage and the fact that electrolytic...
  4. Old Steve

    Wow...he calls it the Scariac!!

    I don't think the "Scariac" is particularly tame. The other stuff isn't so bad, with the guys blowing up caps etc. Looked like fun. Edit: Martin, what annoyed me about the 'Scariac' vid was that he presented it as an 'instructional', with step-by-step instructions on building it. The guy is a...
  5. Old Steve

    Help with open collector output

    Oops, you're right. I accidentally looked at the wrong figure, instead of the gate threshold voltage. I thought it seemed high for a threshold voltage, usually about 10V with a standard MOSFET. It is logic-level. Makes more sense now. (Dunno how I managed that. :rolleyes: ) Still, what I said...
  6. Old Steve

    Wow...he calls it the Scariac!!

    Yeah, me too. I posted a comment on YouTube earlier, voicing my feelings in that regard. The way I see it, someone could easily be killed if they haven't already, and he'd be directly responsible.
  7. Old Steve

    Old AC DC power supply with mechanical rectifier ?

    This is a similar unit, used to charge batteries in the 1920s:-
  8. Old Steve

    Old AC DC power supply with mechanical rectifier ?

    Wow, this looks like it belongs in a museum. What a beauty. It looks like it must be a half-wave rectifier, since there are no change-over contacts. Just the one set. I wonder if it ever really worked properly, or if it was an experiment. Apparently, vibrator type rectifiers were only used in...
  9. Old Steve

    Building an Atari 2600

    That sounds much better. A good project, by the sound of it. You'll learn a lot on that one, and have a much better chance of succeeding. You might want to do a running pictorial commentary of it in the 'Project Logs' section. Then you'll be able to get help along the way as needed. Good luck...
  10. Old Steve

    Building an Atari 2600

    It's good that you have ambition, but you asked if there are any significant problems. Now you know. Forget this idea. It would make an experienced designer cringe. I hope your NES controller, whatever that is, is something far easier. Hopefully it won't need a fancy board or pre-programmed chips.
  11. Old Steve

    Building an Atari 2600

    I thought it might have been only double-layer. If it has internal layers, it will be near impossible to trace, too. Forgot about the schematic. :D I'd still like to see that.
  12. Old Steve

    Building an Atari 2600

    Those chips aren't 'designed for Atari' They're standard CPUs. The listing I linked to said "used in 2600s". It didn't say that they're already programmed for one. (They might be, though, if you're lucky.) And can you make the PCB? This isn't the sort of circuit you can build by 'rats nesting'...
  13. Old Steve

    Wow...he calls it the Scariac!!

    No, you're right there. I couldn't even count how many things could go wrong. Exposed heads of screws that extend into the box, the fact that the plastic box would become brittle over time and could crack/shatter, the lack of an earth connection etc etc etc and etc......
  14. Old Steve

    Building an Atari 2600

    Just looking at one, the CO10745 CPU, it's a pre-programmed CPU. You might be lucky and be able to get some parts here:- http://www.arcadecomponents.com/catalog/item/3054735/3135777.htm Before jumping and buying this chip, contact them and ask if it's pre-programmed. I suspect that they're just...
  15. Old Steve

    Building an Atari 2600

    I haven't checked the parts numbers yet, I'm busy on something else, but I wouldn't be too surprised if at least one of those large, multi-pinned chips is pre-programmed. Are you going to be able to get hold of them? And can you make a PCB for the job? If you really intend going ahead with...
  16. Old Steve

    Help with open collector output

    73's de Edd, you say:- "That area is fed by the Maxim MAX5024 power supply chip which has an option of 3.3 or 5V output." Besides what I said about the open-drain output, that 3.3V or 5V can't be used to switch the SI4906DY dual MOSFET, either - it requires 16V to switch effectively. They are...
  17. Old Steve

    Wow...he calls it the Scariac!!

    There should be rules about people posting videos like this on YouTube. 'Scariac' is right!!! And to think that I wasted all that money buying a variac. :D
  18. Old Steve

    HDMI 5 port switch detecting LED with Arduino

    I made a mistake in my first drawing, labelling the pins wrongly, but just corrected it.
  19. Old Steve

    HDMI 5 port switch detecting LED with Arduino

    I guess you mean voltage, not current. 3.3V directly across the LED? They're usually 1.8V to 2V, for standard, individual LEDs. Anyway, if it really is 3.3V directly across the LED, just use that voltage to directly connect to your Arduino pins. Double-check that LED voltage. If it is as...
  20. Old Steve

    HDMI 5 port switch detecting LED with Arduino

    A couple of points:- Do you really need the 4N25s? Maybe I'm missing something, but can't you connect the HDMI port's LED gnd to the Arduino gnd, then directly sample the LED voltages, above the current-limiting resistors, on the Arduino with 5 digital input pins? You could put a resistor in...
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