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About NEM

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    North Coast, N. Ireland

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  1. I've got one of those and though I've never used it for this type of job, it's got enough power to melt soft solder. You might want to get a pair of these as well; though check them out before using them. The first pair I got had a small hole right on the tip of the index finger, just on the point where you might poke something to see if it was hot! Noel
  2. I'm fairly new to FreeCad, but I can't believe I've not found that website. There's plenty of useful info to read there. Thanks a lot.
  3. That's very impressive. Can you recommend a tutorial on threads in FreeCad? Noel
  4. I have an SPC900NC working correctly on Win10. Search the Philips web site for SPC900NC_00_SW7_ENG.exe.
  5. If you use all three bolts for primary collimation, there's a danger that you'll repeatedly turn them all the same direction and eventually 'walk' the mirror off the bolts. I'm not sure if that applies to the secondary as well. Noel
  6. As I understand it we're only hurtling through space relative to our local group of galaxies. At the speeds necessary for red-shifts to be noticeable, our 'hurtling' becomes glacially slow.
  7. I don't know the specifics of this strip, but I doubt you need to connect + and - together at the end of the strip. I suspect that would damage your power supply or burn out the tracks on the strip. I'd try it without connecting them first, that shouldn't harm anything. You could add your red LED there, but remember you'll need a current limiting resistor in series with it. Noel
  8. So, you're saying I have to fill in the snake pit, remove the trip wire that fires the crossbow bolts and disable the pressure pad under the scope that releases the giant stone ball? You never let me have any fun! ?
  9. NEM

    Stepper motors

    You could use a micro-switch or slotted opto-switch at each end of the travel and get the pi to use them to limit the travel.
  10. That type of clip is known as a Terry Clip. Noel
  11. A wild guess here, from someone who's never even used an A4988, so it's probably not the answer, but... Are you sure there's a negative connection from the Pi to the driver chip ground? What if, when the DIR pin is at 0V it's providing the ground to the driver through internal leakage in the A4988, so the circuit works? Then, when the DIR line goes +ve there's no ground and the circuit stops. Noel
  12. It's the current through the fuse that matters. The voltage rating is only important to stop arcing to the outside. As long as the voltage rating exceeds the voltage you're usng., it's OK.
  13. A few years back, a friend, who's a farmer, asked me to have a look at the PC he used to run his milking parlour as it had stopped working. He kept it in a kitchen cupboard in the barn. When not in use, the doors were kept closed and a 25W or 40W (can't remember exactly, it's been a while) incandescent light bulb provided heat. The bulb had accidentally been turned off overnight and the PC stopped recognising the keyboard. A few minutes work with a hair dryer on the keyboard and all was well again. So, yes, I think your idea is a good one.
  14. Are the surface mount chips already installed on the board when you receive it? I can't imagine soldering U1 in place by hand.
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