Troubleshoot Bell Ringer

Discussion in 'General Electronics Chat' started by jarwulf, Mar 11, 2014.

  1. jarwulf

    Thread Starter Member

    Jul 7, 2013
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    0
    Having trouble with a bell ringer that I am making shown here

    DIAGRAM

    [​IMG]





    MODULE

    [​IMG]



    BACKSIDE SHOWING SLOPPY SOLDERING

    [​IMG]



    It does not seem to work when I hook it up for initial tests. The only thing I could think to do was to test the resistance between all the connections except for those within the transistor and it seemed to be near 0 or the relevant resistor value. I tested the voltage booster by touching the power source directly to its input pads and it lit up properly unlike when normally connected. I checked the power source with an led and it seemed to work fine. In my resistance tests I haven't detected any short circuits from the pads that might look like their inadvertently connected.

    The draw for the device should theoretically be less than 100mA. Around 10-45mA maybe.

    Any ideas what could be going on? Or what other tests I could run to figure it out?
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,979
    3,691
    If you have door buttons with lights, they might be passing enough current to screw up your circuit. The few milliamperes passed by the switch light do not bother a standard magnetic bell mechanism but could fool an electronic 'bell'.
     
  3. jarwulf

    Thread Starter Member

    Jul 7, 2013
    60
    0

    Output goes straight to the bell. I'm not sure what else I can do to test it. I think maybe for some reason not enough current is getting through. Any nondestructive way to test current up to the booster or the transistor?
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    3,691
    Just to check, you do realize that doorbells run off of AC. Do you have a proper rectifier circuit to convert to DC?
     
  5. jarwulf

    Thread Starter Member

    Jul 7, 2013
    60
    0

    Thanks for the suggestions. The Bell is a phone bell not a doorbell. The power supply I am using says it converts to 7.5VDC. In the future I plan to replace the supply with an 8AA battery pack that will supply I suppose 6V and afterward maybe some lithium ion rechargeble.

    Operation: arduino pinx is set to high and that flows to the LL transistor allowing for current to flow through and power the voltage booster which in turn powers the device. This circuit seems to run fine on a solderless breadboard. Unfortunately it doesn't seem to work on this board.

    Additional tests I have run:

    I tested the voltage booster itself by touching leads from the power supply directly to the inputs. Its led lit up properly which it did not do in normal operation of the protoboard but not enough to power the device. In the breadboard the led of the booster lit up and the booster powered the device.

    THe power supply properly lights up an led and I've used it to power the arduino.

    I measured the resistance between all teh connections save the ones through the transistor itself. All were near 0 or the value of the resistor in between.

    I measured voltage via plugging in the multimeter into the positive input and touching the other lead to various points and I found a voltage of 8.75 throughout. Input source is actually 7.5 volts approx not 9V in the figure.

    I tried measuring current. for the pinx to transistor wire. There was a definite signal from the arduino but it seemed extremely low. The led I put in lit up very dimly. When I tried to measure it I only got brief pulses of .001 on the 2m and 0.1 on the 200u current settings. When I measured the current across the negative input wire there was no current I could detect.

    Is there any problem you can figure from this information? Is there any further tests I can do if its still not clear what the problem is?
     
    Last edited: Mar 13, 2014
  6. n1ist

    Active Member

    Mar 8, 2009
    171
    16
    If we are really talking about a mechanical bell removed from a telephone, they run on 90VAC 20Hz. Depending on the phone, you may need a resonating capacitor as well.

    /mike
     
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