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  1. KrisBlueNZ

    How does this circuit work?

    Thanks for the photos. They look good. Well, you COULD replace the micro if you want. The firmware is in the separate EPROM; the micro is not programmed internally. But as you say, that would be a big job. Where are the connectors? The only one I see is the phone jack. Does everything go...
  2. KrisBlueNZ

    How does this circuit work?

    Doug, yes I think you're right about that. My first thought was that the micro was detecting a problem and refusing to start the motor, but since you can move the tread and the micro thinks everything's alright, that seems to imply that there's no other sensor problem.
  3. KrisBlueNZ

    How does this circuit work?

    Ah, the 6303. That was the first micro I worked with when I started my previous job back in 1988! Could you post in-focus photos of both sides the board with good illumination on it? If possible illuminate it at a slight angle and photograph it straight so the photo has no reflection of the...
  4. KrisBlueNZ

    PCB needs repairs

    Good advice there CocaCola. It's very odd that the 5V rail is slightly negative. If there was a short on the 5V rail, I would expect exactly 0V or a slight positive voltage on the left pin of the 7805 relative to the centre pin, and I would expect the 7805 to be getting hot. I suggest you...
  5. KrisBlueNZ

    Led sequencer/scanner

    Here's a schematic of what I think you want. I've shown the LEDs laid out the way I think you want them. There are two rows of 20 LEDs each, and both show the same display. The LEDs are connected into strings. Each string has two LEDs (one in the top display and one in the bottom display)...
  6. KrisBlueNZ

    PCB needs repairs

    OK. Can you confirm for me that you're measuring all your voltages with the black lead of your multimeter connected to the "0V" rail of the circuit board? That's the tab at the top of the 7805. You need to measure all your voltages with the black wire of the multimeter connected to that tab. Are...
  7. KrisBlueNZ

    Led sequencer/scanner

    Yes, both of those transistor types will be suitable. Is the "sn9304" a 2N3904? That's a common type. You're going to have four LEDs on at a time, right? And they'll be connected in strings, with each string consisting of two LEDs and a current-limiting resistor in series? So each transistor...
  8. KrisBlueNZ

    Advise on industrial system

    Good! I hope it works out. I would be interested to see what he is proposing.
  9. KrisBlueNZ

    How to alternate 2 flip flops with 2 clocks?

    Different clock rates will not require adjusting RC values. You just need to ensure that the pulse generated from the slow clock (by the C-R differentiator) is comfortably shorter than the minimum interval between fast clock pulses. If the fast clock is slower than that, the circuit will...
  10. KrisBlueNZ

    How to alternate 2 flip flops with 2 clocks?

    You may KNOW your goal, but you also need to be able to communicate it in your posts. Yes. The same is true of my original suggestion and the earlier 4013-based suggestion that you posted. Right. This is an example of information you should have provided up-front. "What is the range of clock...
  11. KrisBlueNZ

    How to alternate 2 flip flops with 2 clocks?

    Bzzzzt! You don't know how to do what you want; you've admitted that. But you're quite sure that explaining the purpose of your design "doesn't have any bearing" on solving your problem? I'm sure it would at least help me to understand what you're trying to do, and exactly what you need, since...
  12. KrisBlueNZ

    How to alternate 2 flip flops with 2 clocks?

    The description in your second post is not clear enough either. Can you give a general description of what you're trying to do with this circuit? Or is that information classified? Assume that the division will be by 4, and describe the sequence of signals you want on your output, in terms of...
  13. KrisBlueNZ

    PCB needs repairs

    Hi partyanimallighting, I've been following this thread and I think it's time to put my two cents in. You've actually given plenty of information, with your photos of the top and bottom sides of the board. Here's what I've figured out about the design. As you and QuantumCheese have already...
  14. KrisBlueNZ

    How to alternate 2 flip flops with 2 clocks?

    I think you need to rethink your requirements. Your definition of the behaviour you want is not clear. Your first post says "When C1 goes high" and "When C2 goes high" which to me implies edge-triggered behaviour. The 4013-based suggestion will give you edge-triggered behaviour (with a short...
  15. KrisBlueNZ

    Advise on industrial system

    Yes, and it provides electrical isolation too. You could even power the bars independently (assuming power is available at each bar's location), so the only connections between the bars would be the optic fibre. But you would need to use some kind of serial protocol. If you used a simple SPI...
  16. KrisBlueNZ

    Advise on industrial system

    Another interconnection arrangement you could consider is plastic optic fibre. Everlight make a transmitter and receiver that use 1 mm POF, which is readily available and not hard to work with. http://www.digikey.com/product-detail/en/PLT133%2FT/1080-1428-ND/2693975 (transmitter, USD 1.11 for...
  17. KrisBlueNZ

    Advise on industrial system

    It's not the optocouplers that make the difference; it's the idea of using a serial, message-based protocol, with a microcontroller in each stick. You could just as well use RS-485 for the physical connection. Those features require that the bars communicate back to the controller. With the...
  18. KrisBlueNZ

    Advise on industrial system

    So you're suggesting an interface with: +V and 0V (thick wires and connector pins, or multiple) Data (RS-485 differential, 2 wires) (downstream) Data clock (ditto) (downstream) Latch clock (ditto) (downstream) Each bar would receive those three signals, and re-transmit them to the next bar...
  19. KrisBlueNZ

    Led sequencer/scanner

    True the ULN2003 and 2803 are cheap, but don't you want to keep every possible cent of your budget? And what about stripboard to construct the circuit on? You'll need money for that, won't you? If I was in your position I would use discrete bipolar transistors or MOSFETs as drivers. If you're...
  20. KrisBlueNZ

    Advise on industrial system

    This project is to be used in an industrial setting. I wouldn't use a protocol with no error detection, even on a single signal; adding multiple signals that all have to be correct is even worse. And I2C is an open-collector multi-drop bus which is not suited to being transferred over RS-485 (I...
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