Search results

Search Forums New Posts
  1. kellys_eye

    still suffering with a bridge rectifier overheating

    Please read the posts. I was referring to the numbered connections ON THE BOARD. I don't know if those numbers even correspond to where you are measuring???? so how can I determine right/wrong from that? Show a picture of the BOARD, top side and bottom side and measure the voltage ON THE...
  2. kellys_eye

    still suffering with a bridge rectifier overheating

    Just from observation of the top side of the board, the AC from the transformer goes onto the board at #1 and #2, is fed to the bridge rectifier block (grey lump rated at 40V and 5A), smoothed by the big capacitor and then to the regulator IC LM317 whose output voltage is set by two resistors...
  3. kellys_eye

    Another old guy joined

    Join the club! You'll fit in well here!
  4. kellys_eye

    6-V to 5.2V linear regulator

    There are devices called 'low drop out' regulators and even 'ultra low drop out' that will operate from as low as 50mV above the required output voltage i.e. 5.2V output requires only a 5.25V input...
  5. kellys_eye

    Help! Exercise Bike & Elliptical Magnetic Pedal Resistance Controller Circuit Explained

    Nope - scrap that idea. The socketed chip (when seen in close-up) is the EEPROM used to store switch-off paramaters etc. Still, trace the feedback path and/or show it in a pic.
  6. kellys_eye

    Help! Exercise Bike & Elliptical Magnetic Pedal Resistance Controller Circuit Explained

    The signal (feedback) from the position sensor will be read by the microprocessor - probably using a built-in analog-to-digital converter. There may be some form of signal filtering (R-C filter) between the potentiometer and the uP so tracing the wires from the pot, to the board, and there-on...
  7. kellys_eye

    Help! Exercise Bike & Elliptical Magnetic Pedal Resistance Controller Circuit Explained

    The H-bridge controller chip can only move the motor. It does nothing to determine the actual position of the motor (as reported back to the controller) so there has to be some form of feedback. When the motor moves, does it move anything else i.e. a potentiometer? A faulty feedback...
  8. kellys_eye

    Why doesn't my circuit oscillate?

    If it 'stops' oscillating then you have too much attenuation in the feedback path/insufficient loop gain.
  9. kellys_eye

    still suffering with a bridge rectifier overheating

    In the bottom picture, under the yellow wire, there is a three pin device fitted to a heatsink. What is the part number on that device? Can you post a close-up picture of the whole board? I suspect it is part of a simple regulating circuit to develop the voltage to drive the coil(s) and...
  10. kellys_eye

    Led chip appropriate resistor

    The LED will be quite a drain on simple AA batteries however if you use a 12 to 22 ohm resistor you will still have VERY bright lights but at lower current. You will need a 1W resistor (minumum - best use 2W).
  11. kellys_eye

    Help! Exercise Bike & Elliptical Magnetic Pedal Resistance Controller Circuit Explained

    Most certainly they do make integrated h-bridge controllers - sometimes with more than one bridge in a package too. Trace the motor wires back to the board and from there to the IC that 'may' be controlling it then look up the datasheet for that chip - it will tell you what it is.
  12. kellys_eye

    Who's right and who's wrong?

    You are conflating current limiting and current regulation - there is a distinct difference.
  13. kellys_eye

    Optical Sensor Issue

    Have you eliminated the motor as the issue? Sounds to me that the motor is getting the pulses but not doing the movement - could be the motor, could be the driver, could be the supply to the motor/driver.
  14. kellys_eye

    Who's right and who's wrong?

    A fuse is a current limiter. Exceed the current and it cuts it off, true, but it IS a limiter. When you say "a current limiter reduces the current" it actually does no such thing. It stops it rising past a certain level - there is no 'reduction' at all.
  15. kellys_eye

    solar query

    The solar panel and battery are 'separate' by the MPPT which will convert whatever voltage is coming out of the solar panel to the correct voltage for charging (or maintaining) the battery. The battery voltage - assuming a lead-acid battery - will be 14.4V when charging and 12.65V 'at rest'...
  16. kellys_eye

    still suffering with a bridge rectifier overheating

    The coils are an electric clutch and an electric brake. They work by creating a large magnetic field across the face of the plates attached to them and even a 'weak' field will cause one plate to 'attach' to another. Some sewing machine motors use a mechanical clutch to give a 'variable drive'...
  17. kellys_eye

    Generator/Inverter repair

    Sadly the pics don't help - I thought it might be possible to see something I recognised as a potential problem however the iniquitous black 'gunk' has always thwarted such efforts. Looks like you're going to be seeking a replacement part. As for a comment about inference of unreliability, I...
  18. kellys_eye

    Panasonic SAPM-31 Mini hifi, Tapedeck motor running all the time

    The motor is shown on page 80 (bottom). You will need to check voltages around Q1316 and Q1314 and (maybe) go backwards from there.
  19. kellys_eye

    Optical Sensor Issue

    The circuitry should have a 'known position' sensor i.e. a 'zero point' in order to know where to step to when starting from switch on. It can't do it just by counting pulses from that wheel on its own. Is the 'zero' point set (calibrated)? How does it know the zero position? Slot? Magnet?
  20. kellys_eye

    still suffering with a bridge rectifier overheating

    They might also work on the 24V AC supply directly - have you tried?
View older results
Top