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  1. Rleo6965

    IGBT ignition coil driver

    Hey another new word for me . "partially stuffed " means ruined, shorted or defective.:D
  2. Rleo6965

    Initial power surge..

    I forgot the multiple of starting current against normal running current. More than 10 times? this due counter emf, torgue and load of motor. I work as Industrial Technician before in Knitting company and my supervisor mentioned it to me. That's very long time ago.:D
  3. Rleo6965

    IGBT ignition coil driver

    Do you know how many volts you expect on IGBT collector ( - coil terminal )? If its 300V, place 6 pcs zener 1N4757 in series . Cathode on collector of IGBT and anode to ground. This will act 300V zener in IGBT collector to protect it from ringing or spike voltage of – coil when IGBT turn off...
  4. Rleo6965

    IGBT ignition coil driver

    Yes its at high or approximately 1V on gate of IGBT. You have a 33 ohm as current limit. But pulse signal must short as required by ignition coil. Longer pulse will cause overheat of IGBT and got shorted. You mentioned that BC547 was shorted. I assume the cause of damage was a long trigger...
  5. Rleo6965

    Reassurance on Dual Polarity Power Supply Design

    Each capacitor 10,000 ufd with 50V working voltage will be charge of 24V. So, its safe.
  6. Rleo6965

    IGBT ignition coil driver

    Can you tell us which components was damaged. So, we can help analyse.
  7. Rleo6965

    IGBT ignition coil driver

    @mmcIO55 How about placing a 3Amp fuse on +12V supply wire. This is to protect your circuit in case of short circuit and shorted transistors.
  8. Rleo6965

    IGBT ignition coil driver

    Ooops. Sorry steve. Your right. Transistor only conduct if BC547 was turn off . that is BC547 collector was pull up by 1k resistor.
  9. Rleo6965

    IGBT ignition coil driver

    No. BC547 have a base resistor as current limit. I think BC547 was shorted due shorting of transistor on its collector. That transistor have no resistor protect its collector emitter current when BC547 turn on or conduct. So when that transistor have shorted, it will also short BC547. I guess.:o...
  10. Rleo6965

    oscilloscope question

    I can use my old Leader 1021 Oscilloscope measuring 220V AC main. Because I use 2 prongs AC plug for my scope. I removed the 3rd pin or ground prong. But I don’t touch any metal part of Oscilloscope casing or probe when measuring AC mains. But I still suggest that you must use isolation...
  11. Rleo6965

    IGBT ignition coil driver

    @GonzoEngineer My Multiple Spark CDI project have intermittent misfiring problem and I can't avoid using ground because car battery - terminal was connected car body chassis or ground. Here's picture of waveform
  12. Rleo6965

    IGBT ignition coil driver

    Test DC voltage on LM7805 input terminal. It should not be lower than 8V.
  13. Rleo6965

    Intercom noise

    First isolate problem if noise comes from connecting wires of the building. Bring the other Intercom unit near the Master unit and connect necessary wire. If noise or popping sound still persist. Send the Intercom for repair.
  14. Rleo6965

    Trying to identify an SMD

    Diode test reading was ok. Why do you have to remove it?
  15. Rleo6965

    Help with voltage controlled switch

    Likewise here. I can't distinguish schematic symbol of depletion and enhancement mode mosfet. All I know was both were FET. Schematic symbol of mosfet were from ExpressSCH library. Never designed a circuit with Mosfet before. This is my first time. That's the reason I have mistakes with the...
  16. Rleo6965

    Help with voltage controlled switch

    We can use N-channel Depletion Mosfet with its drain connected to ground and source connected to the LED , I wrongly placed N-channel Depletion Mosfet as voltage follower in my 1st schematic.:D twister notice my mistake.:D
  17. Rleo6965

    Help with voltage controlled switch

    8V zener ( non-inverting ) was still higher than 6.2V reference voltage ( inverting ). Non-inverting input need only around 0,5V difference voltage from the 6.2V reference voltage to change its output. 8V zener was only for transient protection as steve suggested. Initially at 13V car battery...
  18. Rleo6965

    A few quick questions

    Try injecting 60hz signal to the input of TDA2050. You can do this by holding a wire and touch pin1 of TDA2050. Free you other hand from ground etch of pcb.
  19. Rleo6965

    Experiment 9; MAKE: Electronics

    You did not connect the other of resistor to the positive wire or capacitor .We removed connection of push button switch to simplify circuit. That's the reason that capacitor does not have charge voltage because current path was discontinued or not connected. Please check if negative wire of...
  20. Rleo6965

    Help with voltage controlled switch

    Then , I have to interchange the circuit on input of LM311. Thanks for the advice.
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