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  1. kellys_eye

    Dual NR 5 DAB Radio. Leak on circuit/power board...

    When you meter a diode it will show as a DC voltage (0.3 to 0.9V - approx - one way, zero volts the other) - if it is showing 0V both directions then, yes, it is probably open-circuit. I'd need a closer look at the board traces to determine if it is as suspected. Some diodes are fitted in...
  2. kellys_eye

    Need help with Dip switches on back of speedometer

    You could apply a (known) signal and adjust ONE switch at a time and note the difference in reading it makes. When you've done all the switches individually - in theory, each individual switch will increase the 'change' by 100% - you should have sufficient information to allow you to trim the...
  3. kellys_eye

    Dual NR 5 DAB Radio. Leak on circuit/power board...

    What range did you use the multimeter on?
  4. kellys_eye

    (1973) Imperial HIFI 2700 stereo decoder and memories

    T103/104 form a voltage regulator developing 17.5V across P08 (P108?) which is then tapped off and applied to the switched presets in the memory bank. The selected voltage is fed to the oscillator via R185(?) - follow it out from the common switch terminal of the channel selector.
  5. kellys_eye

    Car battery jumpstart gadgets

    Naughty of me, I'm sure but I knew I'd read about this somewhere before.... https://www.climateconversation.org.nz/2014/02/man-made-temperatures/
  6. kellys_eye

    RolandXP-50 mainboard repair

    Battery in the right way around? Battery voltage ok? Made any measurements?
  7. kellys_eye

    (1973) Imperial HIFI 2700 stereo decoder and memories

    Selectable tuning - this delivers DC to the varactor-tuned oscillator T101/102. The tuning buttons are interlinked and derived from simple voltage dividers so should be easily traced/repaired. The stereo decoder may just require re-alignment - you can do this by ear if you're careful. I can't...
  8. kellys_eye

    How can I connect this circuit to power?

    I presume you're referring to a power pack and the plug that comes out of it? Those are usually positive on the inside, negative on the outside so, yes, you've probably blown the regulator.... If you cut the insulation from it you will see the part number and can order a replacement although...
  9. kellys_eye

    Best Low-Cost Home PCB Prototyping?

    Pre-sentised board is readily available https://www.rapidonline.com/catalogue/search?Query=pcb%20material
  10. kellys_eye

    serial interfacing

    Coding issue? The serial port connections aren't 'usual' for such comms - have you configured correctly for those control lines?
  11. kellys_eye

    which 1Nm motor should I choose for my solar panel cleaner ?

    Good luck finding a 'cheap' stepper that is capable of 1Nm at 450 rpm! Car wipers systems (including the wash facility) would be an ideal method - cheap, reliable, easy-to-obtain (including spares) 12V operation - no controlling electronics (or basic at the minimum) etc.
  12. kellys_eye

    which 1Nm motor should I choose for my solar panel cleaner ?

    Use a windscreen wiper motor. Consider using the complete mechanism to perform the wipe cycle too. Even the 'new' prices are lower than those RS motors! and you can source used ones from scrapped cars to experiment with.
  13. kellys_eye

    Getting laptop battery to charge

    Such slow charging inevitably means one of internal battery cells has bought the farm - I've never seen/heard of a cure other than cell replacement that works.
  14. kellys_eye

    Can anyone ID this transformer?

    Got to love the 'space optimisation' they employed in those days! Schematic seems just fine - is there a particular issue with it or was your query just about the 'DC' spec of the secondary winding?
  15. kellys_eye

    Pioneer SX-SW515 - missing controller.

    If you can find the internal IR receiver circuitry it 'may' use a dedicated receiver/controller chip, in which case the protocols will be widely available and easily replicated. Sadly, many IR-controlled devices use receivers that feed directly to the central processor where it's all done in...
  16. kellys_eye

    Audio Activated Relay - Circuit Help

    Correct. Correct - the equipment draws only what it needs, no more.
  17. kellys_eye

    which 1Nm motor should I choose for my solar panel cleaner ?

    What's wrong with a standard commutising (brushed) motor? You can get them in many voltages and with gearbox reduction. No elaborate control circuitry (on-off!) and just a pair of limit switches.
  18. kellys_eye

    Best Low-Cost Home PCB Prototyping?

    I use the ' I use the 'shiny' backing paper left over from adhesive stickers (the backing) - laser toner can almost (in fact quite easily) be wiped off with the finger such is its non-adhesive quality. It retains enough stickiness to get the toner where it's needed though. And I then use a...
  19. kellys_eye

    Basic LCD bidirectional power oscillator

    Yes on the Hz - it would be better if you studied the basics of LCD manufacture and driving via a dedicate site such as this: https://www.lxdinc.com/pages/technical_resources#
  20. kellys_eye

    Audio Activated Relay - Circuit Help

    All the modules (and the control signal) require a supply (or signal) line PLUS a ground - this is where the voltage/signal flows to in any circuit (simply speaking). It is standard practise to join all earth's (at a common point ideally) to prevent circulating currents which can manifest...
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