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  1. kellys_eye

    Where to start

    There are hundreds of online resources with beginners information - websites dedicated to it and, of course, good books. I find that a book is by far the best resource - something along the lines of 'Learn C Programming in 28 Days' (not sure if that's a real title but it sounds familiar!) -...
  2. kellys_eye

    massage chair model 948

    Not enough information - is there a manufacturers name? Do you have the operators manual? How does the fault manifest itself?
  3. kellys_eye

    Programming starting point

    I'm allowed to use my blunt crayons and soft paper (under supervision) to scribble a nice flowchart, coloured-in of course, before getting approval from my nurse to translate this into punched cards before being returned to my padded room. Back in the real world.... the flowchart still applies...
  4. kellys_eye

    Network Time Display

    No they're not. They're the same as small LED modules - only more of them.
  5. kellys_eye

    Increase In Output Pulse As Supply Increases In 555 Timer, Why?

    Use a regulated supply.....
  6. kellys_eye

    Linear or switching regulator?

    Depends what you feel is acceptable 'losses' in the system. For a simple LDO regulator and 5V drawing 3A you will have to drop 19V @ 3A in the regulator - a power loss (heat dissipation) of some 27 watts....... A switching regulator might have 90% efficiency so losses would be only 2.7W...
  7. kellys_eye

    555 Timers

    There are some SOIC and DIP to TO8 adapters around: https://www.digikey.com/product-detail/en/aries-electronics/1109523/A330-ND/32013 or https://www.digikey.com/product-detail/en/aries-electronics/1109814/A799AR-ND/4208741 that might work. You need fairly deep pockets to justify them...
  8. kellys_eye

    Trying to reuse old phone parts (screen and camera)

    That display panel looks to be a 'bare' board in that it doesn't have any signal processing circuitry on it so it would have to be addressed using a complicated digital processing procedure to develop the RGB signals and synchronisation etc. Hence the requirement for the display part number and...
  9. kellys_eye

    Switch 24Vdc signal using opto transistor

    Put the resistor in the collector circuit and ground the emitter. Take the signal out from the collector.
  10. kellys_eye

    Board identification problem(NAS Board ?)

    Tried powering it up and attacheing a USB device?
  11. kellys_eye

    Capacitors in Audio Applications?

    Capacitors have 'reactance' which, for the sake of simplicity, can be considered as 'AC resistance'. The amount of resistance it offers to a signal is related to the value of the capacitor and the frequency applied to it. Its' resistance (reactance) is given by 1/2.pi.f.C where f= frequency...
  12. kellys_eye

    Trying to reuse old phone parts (screen and camera)

    You'll need the BOM from Sony to discover the model number of the screen being used. Since it's only 320x240 resolution and there are dozens of such displays on module boards all over eBay for a few $'s it hardly seems worth the time/trouble to investigate an unknown board with inaccessible...
  13. kellys_eye

    Camera film enlarger transformer blown help.

    SE2 and SE4 are date codes (manufacture) so are pretty much irrelevant in use.
  14. kellys_eye

    Camera film enlarger transformer blown help.

    PME is a class X2 suppressor PMR is a class X1 suppressor Class X1 is 'better' than class X2 in the sense that you can always fit a better class in place of a lower class but not the other way around.
  15. kellys_eye

    Need LED bulbs and power supply for repair.

    They sound like standard 5mm LEDs to me - they come in a variety of packages, taperd, round top, flat top, top hat, triangular etc etc. Please post a picture of them. Either way you could just go to a component suppliers site and list the LEDs therein and physically match up the devices. The...
  16. kellys_eye

    Camera film enlarger transformer blown help.

    Common fault - easily replaced. Do it.
  17. kellys_eye

    Any SDR users?

    My most recent ham radio purchase was a Nooelec SDR receiver and I've spent more time arranging a decent antenna for it than actually exploring its functionality. One area that leaves me perplexed is the software choice to run the SDR with. As much as I've read reviews I've not heard from...
  18. kellys_eye

    CNC Plotter with DVD stepper motors

    Darn it! I wrote all the above for nothing!
  19. kellys_eye

    CNC Plotter with DVD stepper motors

    Are you microstepping or are the motors driven as 'full step'? Can you switch between the two? D10 and D11 seem much more like what I'd expect. In 'full step' mode these voltages should be around +5V and 0V (which is what you have for D8-D11). One motor controls up/down, the other motor the...
  20. kellys_eye

    CNC Plotter with DVD stepper motors

    Use the external 5V rail for the pull-ups (as it's the L293's that require the input levels). There is a 'sort of' sequence appearing but without the pull-up resistors these aren't properly defined - hence the problem both measuring them and getting the motors to work.
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