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  1. kellys_eye

    Diy multi bank battery charger

    OK - the 'direct approach' - I like your style! Another suggestion would be to visit the semiconductor manufacturers websites for application notes on the process - there are linear and SMPS solutions to this kind of thing amongst them (from memory) but it may involve more 'design' than you're...
  2. kellys_eye

    Beginner needing help - Simple timer circuit for reversing 5v motor

    Any of the smaller PIC devices will be capable of driving the motor via a small dedicated h-bridge driver or just a couple of transistors in a discrete circuit. The hardest part for you will be getting the code right! I'd suggest instead that you get an Arduino kit, purchase a motor driver...
  3. kellys_eye

    UV LED PCB Lithography Exposure Unit

    I've got a similar unit but using UV LED strips and installed in an old flatbed scanner case. The glass and lid are perfect for the job and the original external PSU is re-used for power. I intend to fit a digital timer but that's a winter project on the back burner for now.
  4. kellys_eye

    Recapping a PSU -choosing the right replacement caps

    After 30 years I'd be changing them as a matter of 'good practise' regardless! Dried-up electrolytics are now a major cause of equipment problems/failure. I've come across this issue many, many times and would be doing what the OP is suggesting without batting an eyelid.
  5. kellys_eye

    Finding the right switch

    The function of the switch depends on what you want to achieve and would be selected to meet your own needs/spec. What you could do is fit an internal microswitch that is operated when the radio tuning dial is at one extreme or another. The tuning capacitor usually has a larger plastic drive...
  6. kellys_eye

    Is it possible to replace a single speaker with an aux port?

    I love the definition of 'vintage' - in this case it being 1975...... I was 16 years old then!!! Darn I feel old! Anyway, if the radio has any particular value to you then consider purchasing another to salvage parts from - such sets are available on a buy-it-now basis for $25 on eBay.
  7. kellys_eye

    Crappy desk clock

    Most permanently-lit LED clocks are mains powered for the obvious reasons..... if you think back (or are old enough to remember them) LED watches used to require the user to push a button to momentarily light the display to conserve battery power. Even using a multiplexed display such a clock...
  8. kellys_eye

    Yamaha psr e403 low sound output from speakers

    Does the volume vary at all? Is there an external output port (headphone socket perhaps)?
  9. kellys_eye

    Speaker not working

    If the speaker has been dropped then it may have a loose or broken connection inside. The other possibility is that the speaker itself has 'blown' and would need replacing. Time to open it up and have a look inside.
  10. kellys_eye

    Is it possible to replace a single speaker with an aux port?

    Have you looked to replace the speaker? They are fairly easily sourced and don't even need to be 'exactly' the same size as the original if you use a small adapter plate (thin ply will do) to ensure a good fit. If you're referring to an 'aux' port on the radio this may be for an external input...
  11. kellys_eye

    Finding the right switch

    The only types I've come across have been used in oscilloscopes whereby the knob has a 'pull out' position as well as the conventional rotary-and-switch function. Not sure where you'd go to get one either as the carbon track values have to have a suitable resistance and a logarithmic function...
  12. kellys_eye

    Is a 3000 watt 12v to 120 inverter really just 2 1500 watt inverters ?

    Dodgy practise to use inverters rated at (or close to) the needed wattage - far safer to include a margin for 'error' and increase the wattage by 20-50% therefore for a 3000W load you should look to use a MINIMUM of 3600W (next one up is probably a 5000W unit which would be ideal). When you get...
  13. kellys_eye

    Maximum battery charging using small generator idea

    Assuming a 3000W motor then...... (and 100% efficiency)... @12V this equates to 250A. To pull an anchor up for, what?, 3 minutes??? A 'total' of 12.5Ahr...... (note that the 250A load won't be continuous due to heaving cable as opposed to heaving the anchor when it leaves the bottom)...
  14. kellys_eye

    Recapping a PSU -choosing the right replacement caps

    Low ESR and (typically) a temperature rating of 105C is what to aim for. Ichicon are a good 'name' but if purchasing from a reputable stockist you should be getting a decent product anyway - certainly Panasonic should fit the bill. Have you checked to see if replacement NOS (New Old Stock)...
  15. kellys_eye

    Understanding LED brightness (mcd and viewing angle)?

    Get some 'straw hat' type LEDs and some cheap ping pong balls. Fit the LED and battery inside the ball for a nice diffuse light effect that won't blind anyone.
  16. kellys_eye

    Crappy desk clock

    Zeroly, what kind of clock? Digital, analogue.... link to a website perhaps? Firstly, what type of AAA cells are you using? Cheap'n'cheerful or pukka? The capacity of such cells varies enormously and you most often get what you pay for. Secondly, are you sure there isn't some additional...
  17. kellys_eye

    Design LED driver according to IEC 62384

    Check out the manufacturers websites of companies that deliver integrated package devices for such applications as they often have 'design software' that does all the donkey work for you or they have detailed application notes on how to design for a specific end-purpose. Analog, Maxim, Linear...
  18. kellys_eye

    Can I replace a fused UK plug with a regular plug?

    Given the generic Dremels (here in the UK anyway) aren't protected by the fuse in the plug (that protects the cable, as already mentioned) then there will, of course, be some other 'fail safe' in the device somewhere - (here's a 'wild assumption') whether this is a thermal fuse (potentially) or...
  19. kellys_eye

    Roland XP60 no sound

    'Quite hot' is a relative concept! Such parts are designed to get 'quite hot' which is why they're attached to metalwork - a heatsink. The only true test of those parts is to measure the voltages in and out of them. Does anything on the keyboard 'light up' or otherwise show that power is...
  20. kellys_eye

    Diy multi bank battery charger

    Sorry for the distraction! Whilst I haven't done a comprehensive search, the item linked to below is a cheap and useful device to charge LA batteries...
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