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  1. kellys_eye

    Power Electronic Keyboard with 12v Car Battery

    Make sure you use a cigarette power plug that has an integral fuse and use the correct rated fuse too.
  2. kellys_eye

    Can't identify a single chip from my circuit board. Need help.

    To what end? You should be able to access and reprogram the EPROM using the ODBII bus in the vehicle. In-house codes are notorious for identifying. The EPROM is the device under the blue clip holder........
  3. kellys_eye

    In need of a great power supply

    Can you get hold of the LT1083 device? This is a 3A (or 5A or 7A, depends on the sub-set device you choose) and pin-compatible with the LM317. Saves all the extra circuitry. Current limiting down to 10mA seems a bit excessive but the LM317 (or LT1083) can be wired as a current limiter using...
  4. kellys_eye

    Electric Fence Charger

    What voltage do you measure across that capacitor when the unit is powered? The most common problem with fence energisers is the main discharge capacitor - looks like the big blue rectangle on your board (??? 5.6μF ???) This is the most stressed item in the unit and the symptoms include a low...
  5. kellys_eye

    Discharging laptop batteries

    Just run the battery down until the system alarms for 'low battery'. Shut down and let the battery fully charge. The idea is to prevent the battery obtaining a 'memory effect' that happens when you only PARTIALLY discharge a battery i.e. recharge it when it drops to only half-full (or 3/4 full...
  6. kellys_eye

    Help!

    It's said that Americans 'don't get irony....' (not meant as an insult, I can assure you! but you were the only respondent that came back with an answer. If my request had been truly heartfelt and not, as posted, tongue-in-cheek, I would have appreciated your reply for the genuine intent - for...
  7. kellys_eye

    Electric Fence Charger

    Make, model, schematic, pictures?
  8. kellys_eye

    MPPT for truck, alternator/solar

    Older alternators should NEVER be used without a load connected as the output can rise beyond safe levels (in an open-circuit). The Redarc device is unknown to me - does it load the alternator output to maintain regulation or does it actually 'disconnect' leaving it floating?
  9. kellys_eye

    Mephisto Chess computer problem

    As with most old electronics, if there are electrolytic capacitors on the board, CHANGE THEM.
  10. kellys_eye

    Kindle Fire 1st gen.

    Get another one for $15...... seriously - any other repairs would cost you more than getting another unit (hopefully one with a different fault) that you could swap working parts between.
  11. kellys_eye

    Public Signaling

    This could be problematic given signal attenuation. What size building? What form of construction? You may need multiple antennas and/or signalling positions. Suggest you purchase a pair of PMR walkie talkies and see how well (if at all) they work in the areas you plan to use the signalling...
  12. kellys_eye

    MPPT for truck, alternator/solar

    A properly working vehicle alternator will output 14.2-14.4v on-charge. 13.8V is the off load voltage of a fully charged battery. Without knowing the internal structure of the charge-controller commenting properly on isolation diodes etc is speculative - no harm in adding them! Using an MPPT...
  13. kellys_eye

    Convert 12V to 3V Without affecting Total Resistance

    I've read, but can't confirm by experience, the the analogue input impedance is around 20MΩ. But there is conflicting information everywhere! The only real answer would be to test it yourself.
  14. kellys_eye

    Book: Transistor Circuit Design, With Experiments, by Delton T. Horn

    ...specifically?
  15. kellys_eye

    Failure due to condensation

    These should be in the 'homework' section..... Silica gel is the usual transportation additive. Packed in a temperature controlled atmosphere and into a well sealed box they wouldn't suffer anything the silica gel couldn't cope with.
  16. kellys_eye

    Technical Cleanliness: Contamination Cleaning

    2. Solder masks. NDT (pin board). Optical sensing etc. SMD IC's would be most prone but as mentioned, solder masking and the reflow oven procedure should prevent any of that happening.
  17. kellys_eye

    MPPT for truck, alternator/solar

    The alternator will connect straight to your battery (via the diode). Everything else will be connected as per the last of your pictures. The wind and/or solar will charge the battery or, when the motor is running, the alternator will do it. Fuses should be used in the battery and alternator...
  18. kellys_eye

    What reason could be for a food processor's motor to run backwards?

    Has the blade been refitted and put in 'upside down'? Might explain why the plastic is cracked?
  19. kellys_eye

    MPPT for truck, alternator/solar

    A diode from the output of the alternator to the positive of the battery will suffice. Diode should be rated at twice the current capacity of the alternator.
  20. kellys_eye

    MPPT for truck, alternator/solar

    I wouldn't know - you don't post any details of the make/model....
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