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Circuit switching problem

Discussion in 'Troubleshooting and Repair' started by Bilal Ashraf, Jul 21, 2014.

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  1. Bilal Ashraf

    Bilal Ashraf

    Jul 21, 2014
    I have a problem with a circuit which is designed for switching . this circuit work is to pass the 220 v supply to the double action solenoid hydraulic valve . hydraulic valve have 2 coils . each coil have 2060 turns of copper wire gauge number 35 ,and the circuit is pass supply one by one to these 2 coils . a photocell is fix to set the paper roll . three wires of sencer are connected in this circuit . when the sencer sence the paper position it gave a pulse to transister that it pass the supply to coil .circuit operating supply is 12 v DC . and switching supply is 220v . there are 2 transisters BT 136 on circuit for switching one by one . now problem is that after 4 or 5 minuts of working it any 1 transister is burn out and bypass the supply to coils . when 2 coils take supply together then these are brun out . how can i control this problem why the transistor are burn out .
    help me .
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
    Can you post a schematic?

    The BT136 is a triac, not a transistor. Do they get hot?

    Do you have any kind of suppression across the solenoids? Usually a resistor and a capacitor in series are connected across inductive loads to suppress the back EMF. Google RC snubber.
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