Cordless Screwdriver motor don't run without crocodile cable

Discussion in 'General Electronics Chat' started by jeolex, May 3, 2015.

  1. jeolex

    Thread Starter New Member

    May 3, 2015
    23
    0
    Hello my friends,

    I ve got a cordless screwdriver which has finished battery and broken button. I decided to get an adapter and connect a button. I made it but I ve got a problem. When I try to connect adapter cables to botton and motor, it s not run. I ve used soldering, socket, connector etc. and it just give movement and stop again give movement and stop. But when I use crocodile cable, It s run smoothly. I couldn't understand that is there a special feature in crocodile cable.

    Thank you..
     
  2. #12

    Expert

    Nov 30, 2010
    16,257
    6,757
    There is some other mistake in the mix. Photos might help. A drawing of the circuit if that's within your ability.
    Yes, I know, a battery operated screwdriver is dead simple, but each one is a bit different from the next.
     
  3. jeolex

    Thread Starter New Member

    May 3, 2015
    23
    0
    I ve attached images. This circuit run with no problems. But when I try to connect adapter cable (you can see in images) with soldering, socket, connector or by hand, it is not run. Motor is hesitating for run :) WP_20150503_006.jpg WP_20150503_008.jpg WP_20150503_010.jpg
     
  4. #12

    Expert

    Nov 30, 2010
    16,257
    6,757
    My first guess is that the motor requires a starting current that is more than the 3 amp supply. When you provide excellent connections, the supply goes into self-protect. The alligator causes a weak connection (compared to solder) so the power supply is protected from the motor by a weak connection. You might try a big capacitor in parallel with the power supply so it can suffer the first surge, or you might be forced to buy a bigger power supply.
     
  5. jeolex

    Thread Starter New Member

    May 3, 2015
    23
    0
    I have only 10microfarat 50v alliminum capacitor. I tried it but it s not run again :) I think my capacitor is not enough. I checked alligator cable and it s copper wire, not a good one. If power supply is not enough for first surge, how is it run with alligator. I could'nt get it..
     
  6. #12

    Expert

    Nov 30, 2010
    16,257
    6,757
    A resistance in series with the motor will reduce the current that can flow.
    A poor quality wire with a rusty alligator has resistance that limits the maximum current.
     
  7. jeolex

    Thread Starter New Member

    May 3, 2015
    23
    0
    Hımm I get it now. Thank you. Could you suggest a capacitor, which value I have to use.
     
  8. Ramussons

    Active Member

    May 3, 2013
    557
    92
    try a 4700 uF @ 16 volts
     
  9. jeolex

    Thread Starter New Member

    May 3, 2015
    23
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    Thank you for your reply, Could you tell me how can you estimate which capacitor is enough for me. Is there a formula ?
     
  10. Ramussons

    Active Member

    May 3, 2013
    557
    92
    No, there is no simple formula as far as I know. I'm doing a guess from past experience on something similar. I had managed with 2200 uF, but settled for 4700 uF.
     
  11. wayneh

    Expert

    Sep 9, 2010
    12,093
    3,031
    Well there is a formula, but the problem is not having the parameters to plug into it. With good data on the motor, it would be easy to calculate what is needed. Lacking that, find a big cap that works and work down to lower values until it doesn't work. If the big one fails, you'll need another solution.
     
  12. jeolex

    Thread Starter New Member

    May 3, 2015
    23
    0
    What is the good data about motor ? Such as current, voltage of motor. I know old battery values. And I m sorry for my lack-information, I have questions. for example I need 4700uF capacitor for motor, but I dont have it, I have bigger one so is it work ? Or ı need exact value ?
     
  13. Ramussons

    Active Member

    May 3, 2013
    557
    92
    doesnt matter. try it out.
     
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  14. jeolex

    Thread Starter New Member

    May 3, 2015
    23
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    I tried 4700uF and 6300uF capacitor, but result was same. It s not working. I still dont understand why it is run with crocodile cable and dont run with soldering, socket, plug etc.. !!!
     
  15. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,969
    744
    are you using the same power supply for the crocodile clips as you are for soldiering to the motor ?
     
  16. jeolex

    Thread Starter New Member

    May 3, 2015
    23
    0
    Yes I use same one, you can see above. It s interesting that I used 5v 3a power supply, I tried directly connect with motor and It could run it. But when I use button and connect powersupply cables with soldering, sockets, plugs, connector or by hand It is not run, just give movement then stop give movement then stop.. If I use crocodile cable for connect powersupply cables It is run.

    It seems there is no need capacitor, just need to understand why it is only run with alligators. :))
     
  17. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    Does it run if you connect the alligator clips to the wires that connect to the button? In other words, you need to eliminate either the socket/plug or the button as the reason it won't run. So try it with the alligator clips and button, or socket and direct write to the motor. Either you button or your socket is the problem.
     
  18. Glenn Holland

    Member

    Dec 26, 2014
    353
    110
    From the picture, your power supply is 3.0 amps which should be sufficient to run the device with no load and probably with a load.

    Try connecting the power supply directly to the motor terminals.
     
  19. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,969
    744
    sounds like its the button switch thats dicky, if you solder the psu directly to the motor it works ok? If so then try it with the switch in and see what happens.
     
  20. jeolex

    Thread Starter New Member

    May 3, 2015
    23
    0
    when I bought power supply (adapter), first I tried to connect cable to motor directly and it was run. So I thought that it will run motor. I tried 2 different button but it wasnt run. Then connecting adapter cables to button with alligator it was run. I dont understand what şs matter with alligator
     
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