SCR firing circuit using 555

Discussion in 'The Projects Forum' started by jignacio, Dec 5, 2012.

  1. jignacio

    Thread Starter New Member

    Nov 20, 2012
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    Hi, anybody who could help me building my own battery charger using SCR. I have 2 pcs. of 12 Volts 200Ah battery, our 24 volts battery charger was stolen. I have a 32 volts 30 Amps transformer and I am willing to buy a new SCR also I want to use 555 timer IC to trigger the SCR so that I can adjust the necessary current needed for my battery. Anybody could help me would be very much appreciated. Thanks in advance.
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Just a naked transformer making 32V AC? Or does it already have a rectifier, filter and regulator making 32V DC?
     
  3. crutschow

    Expert

    Mar 14, 2008
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    If you have only a transformer, then you just need a phase-control circuit for the SCR as described here. You don't need to use a 555. Also you don't need to add a capacitor filter on the output since the battery will act as a large capacitor.

    But note that you will likely need to add some inductance or resistance in the circuit to limit the peak current, since the transformer voltage is much higher than your battery voltage. An SCR by itself will not limit this.
     
    #12 likes this.
  4. #12

    Expert

    Nov 30, 2010
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    Thanks. I haven't taken a jab at this because I can't figure out why you need a 555 to charge a battery.
     
  5. wayneh

    Expert

    Sep 9, 2010
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    +1
    I assumed he was thinking of PWM to control current, but that's just a guess.
     
  6. crutschow

    Expert

    Mar 14, 2008
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    Well, AC phase control is a sort of PWM. ;)
     
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