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  1. Rleo6965

    Experiment 9; MAKE: Electronics

    Welcome to the world of electronics.:) Be one of us.:D
  2. Rleo6965

    Very simple quick problem

    If you can still find small flashlight bulb. Break the glass and expose the filament. That maybe a help.
  3. Rleo6965

    Automotive Question

    Designers have reason of putting only 11 watts 3.3 Ohm resistor. Maybe it was designed to open if prolonged excessive current in the circuit.
  4. Rleo6965

    Inverter problems

    Try using higher wattage iron core transforner.
  5. Rleo6965

    Air Plane Crashes (Pilot Error)

    Too much computer in controlling airplane sometimes not advisable. Pilot's tend to forget how to fly or land plane safely.
  6. Rleo6965

    Want to build ESR Tester

    Can you share the link? Thanks in advance.
  7. Rleo6965

    LDR Motor Circuit

    This is the reason I'm sticking here in Electronics Point. I'm really learning new things to me from you guys.
  8. Rleo6965

    Velleman K8055 blowing up ULN2803

    Your welcome neil, I'm glad it works. Those small capacitors in the terminals of dc motors were noise filter for the carbon brush. For the 24V motor. Try not to connect any wire to motor body and observed. Just use the 2 terminals. Roger
  9. Rleo6965

    Velleman K8055 blowing up ULN2803

    Yes, your right . You need to placed diode as shown in diagram. 1N4001 will do. Diode will serve as one way switch. ULN2603 output can pull down end of relay but will not pass negative voltage.
  10. Rleo6965

    LDR Motor Circuit

    The reason I recommend steve because I'm not really an electronic engineer. I'm only a Radio TV technician with 40 yrs experience in electronics and computer repair.:D I'm not expert in interpreting datasheets.:)
  11. Rleo6965

    LDR Motor Circuit

    He is a "super moderator" here in Electronics Points.
  12. Rleo6965

    LDR Motor Circuit

    That current reading was without load. You need around 10A of npn transistor to drive the motor. This was reason BD139 got hot. BD139 have only 1.5A collector current. Let's wait for *steve* to recommend required transistor.:)
  13. Rleo6965

    LDR Motor Circuit

    Please try to measure current draw to dc motor. Apply dc voltage to the motor and place ammeter in series to ground. This will be our current reference for selecting transistor and base resistor.
  14. Rleo6965

    LDR Motor Circuit

    You should connect base resistor to limit current of base. This is to avoid to much current on collector to emitter. Try place 4.7K resistor.
  15. Rleo6965

    Velleman K8055 blowing up ULN2803

    What is HS1 and ES1 in your diagram? To confirm that negative was cause of damage of ULN2803. Check the resistance of pin11 and pin12 with respect to ground pin of ic. If all the IC have same defect of open pin11. That will confirm negative from dc motor cause of damage. You have to avoid...
  16. Rleo6965

    Unknown LED symbol

    @GonzoEngineer Your older than me. I'm 62 yrs old and also never saw that symbol before. It might be part of schematic diagram of flying saucer anti-gravity generator.:D
  17. Rleo6965

    Velleman K8055 blowing up ULN2803

    Here's a weird possible cause of damage to ULN2803. This is my theory only and I'm maybe wrong. I'm thinking that it's possible that "dynamic braking" of DC motor was cause of damage to ULN2803 output pin. DC motor generate dc voltage when rotor was rotating mechanically. A situation maybe...
  18. Rleo6965

    repair PCB

    If flash really necessary. Point your camera in an angle to the board that in such a way reflection of flash will not reflect back to camera. Usually with burnt damaged pcb etch. I cut all burnt or carbonized portion of pcb and place jumper wire for connecting new replaced part. This is to...
  19. Rleo6965

    Problems building first circuit - capacitor ESR meter

    According to Wikipedia about forward bias of Schottky diode.
  20. Rleo6965

    Velleman K8055 blowing up ULN2803

    No need. I will figure it out. Will reply post tomorrow.:)
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