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  1. Old Steve

    Multi-input D flip-flop?

    I use old versions of PICBasic Pro for Basic and Knudsen CC5X for C, both from inside the MPLAB IDE. Since I'm running XP, though, I can only use V6.6 and no later. Does Microchip have a free C compiler now, or do you use assembly? (They used to only provide a free assembler.)
  2. Old Steve

    Unusual 12V SLA Charger Circuit

    I'm not real sure about C1. I haven't looked at that circuit for many years until now, and this type of analogue circuit isn't my strong point. It works well though. Maybe C1 stops the bottom of C2 from going too low, so that the battery isn't pumped up too high when the MOSFET pulls it up. If...
  3. Old Steve

    Multi-input D flip-flop?

    Wow, I wasn't aware of those prices. I'm shopping in the wrong place. :mad: Actually, neither my compiler nor programmer support the 16F1826, but both support the F54. For small projects, I stick to the 'F84A-20, 'F628, or 'F876 for mid-size, for convenience rather than cost. And I don't want...
  4. Old Steve

    Unusual 12V SLA Charger Circuit

    I sort of follow it. First note that the MOSFET drain is attached to the unrectified transformer secondary, not to DC. So, when the AC waveform drops, the MOSFET switches off and C2 charges via the MOSFET's inherent source-drain diode, then, when the AC voltage rises, the MOSFET is switched on...
  5. Old Steve

    Need Help in mosfet switching strobed LEDs

    No, me neither. I just decided to go with the flow. :D (The die would need to be re-built to do that.)
  6. Old Steve

    Help with a project

    What about setting up a slider type pot under the 'pressure switch', with the wiper voltage used to control the LEDs? A spring could raise the 'switch' when pressure is released. (I'm assuming you're supposed to make the switch yourself.) I've given no thought to the associated circuitry. Since...
  7. Old Steve

    Electro magnet

    It's fairly straightforward, if you carefully read the information on this page, under "TheCoil":- http://aaybee.com.au/Magnabend/Building Your Own Magnabend.html They explain it all very clearly and I couldn't do better than they have already done. Basically, you first need to make a soft-iron...
  8. Old Steve

    Unusual 12V SLA Charger Circuit

    Like a dummy, I connected my SLA charger to the battery backwards last night, heard a 'crack' and smelled the magic smoke. I connected it to the battery without the mains connected yet, by the way. I pulled it apart and fixed it, (only a track was damaged), but in the process was reminded of...
  9. Old Steve

    Need Help in mosfet switching strobed LEDs

    Sounds like the P-channel has some strange internal arrangement with the internal diode backwards. I actually explained this in post#3, near the beginning of this thread:- A high-side driver is the answer. A high-side driver generates a voltage higher than the supply voltage, usually using a...
  10. Old Steve

    Multi-input D flip-flop?

    Yep, nice and cheap too. $4 from Hong Kong for a PIC16F84A:- http://www.ebay.com.au/itm/1pcs-PIC16F84A-04-P-PIC16F84A-16F84A-18-pin-NEW-m-/180718425788?hash=item2a13a856bc
  11. Old Steve

    Electro magnet

    Right, now I'm 100% with you. I have to confess that I only watched the first minute or two yesterday, since the video is 10 minutes long.. It'a a nice machine, isn't it? So, it doesn't use solenoids at all. It's a full-length, very powerful, electromagnet. I didn't realise it was open-ended...
  12. Old Steve

    Multi-input D flip-flop?

    The way to achieve something like this in only one chip would be a PLD, I think. Never used one, but I asume they have flip-flop functions.Otherwise, a single flip-flop, with diodes as described earlier, and a multiple-input XOR driving the clock input. (2 chips) There's not enough call for...
  13. Old Steve

    Mind & Infra Red Controlled Robot Car

    First up, get yourself a cuppa before starting on this, it might take a while to get through. Officially the longest post I've ever typed on a forum. Not having either an Arduino or that particular brand of motor shield, (or any other for that matter), that's pretty hard to answer. The...
  14. Old Steve

    Need Help in mosfet switching strobed LEDs

    So now you need to go and buy some 'real' P-channel MOSFETs. ;)
  15. Old Steve

    Multi-input D flip-flop?

    Yeah, hence the three diodes. A diode OR. Don't you have 'Paint' or similar on your machine to draw a diagram? Only takes a minute or two.
  16. Old Steve

    Need Help in mosfet switching strobed LEDs

    That first diagram of your's just above doesn't make sense - the internal diode would be conducting and the MOSFET would not switch off. I'm afraid you've lost me. And in the second of your above diagrams, you're right back where you started - the top MOSFET couldn't be switched on until the...
  17. Old Steve

    Need Help in mosfet switching strobed LEDs

    Note the internal diode in this drawing:- Picture if the MOSFET was in backwards - the diode would be forward-biased and conduct.
  18. Old Steve

    Need Help in mosfet switching strobed LEDs

    This shouldn't be this hard. You followed his tests exactly and it tested similar to his measurements? That's odd - your's is a P-channel and he's testing an N-channel. Getting back to the MOSFET not switching off in-circuit, if the drain-source isn't short-circuit, then something is fishy. If...
  19. Old Steve

    Need Help in mosfet switching strobed LEDs

    Dead MOSFET! With the circuit unpowered, measure between drain and source with a multimeter. I'll bet it measures a dead short - dead MOSFET. Attaching the gate to the source, +12V in your case, should switch it off if it's a healthy MOSFET. Got a spare? (Never buy just one of a part when...
  20. Old Steve

    Need Help in mosfet switching strobed LEDs

    What he ^ said. (I already outlined this in my post #3 as well.)
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