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220 VAC to 24 VDC

Discussion in 'General Electronics Discussion' started by kunwart, Oct 1, 2011.

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  1. kunwart


    Oct 1, 2011
    Good Day
    I M newly start electronics project. I need the 220 VAC to 24 VDC 300mA circuit diagram. Kindly help me any one in this regards.
  2. jackorocko


    Apr 4, 2010
    I think you could do this easily with a voltage regulator, there are plenty of circuits, even on this website. Do a search

    You may also find the datasheets on the LM317 very useful.
  3. kunwart


    Oct 1, 2011
    Need Help for circuit

    I M newly start electronics project. I need the 220 VAC to 24 VDC 300mA (without Transformer) circuit diagram. Kindly help me any one in this regards.
  4. davelectronic


    Dec 13, 2010
    power supply

    Hi kunwart.
    First you need a transformer to step down the 220 volts AC to say about 28 to 30 volts AC and a current of 1amp or so would do, also stated as ( VA ) volt amps, 25 to 30 would do fine, next you need to build a bridge rectifier to covert the AC to DC which will be say 28 volts DC, from there it needs smoothing or filtering with an electrolytic capacitor, say 40 volts 2200uf.

    After that comes the voltage regulator a 78L24 this is a 24 volts + fixed voltage regulator at a current maximum of 1 amp, so ok as you only want 300 milliamps.

    Then you need a couple of ceramic disk or other decoupling capacitors, and then a 40 volt 100uf capacitor or a bit less capacitance, but same voltage 35 to 40 volts is fine.

    Finally a load resistor on the output say 1k ohm 0.5 watts.

    You must fuse the input on the live rail, and its best to fuse the out put on the live rail.
    All the above would keep you busy for a wile, if your set on building a power supply.

    One of the fixed voltage regulator circuits using the components above will be fine.

    Or if its just to get a quick power supply, then there are plug in power adapters, but for 24 volts there not all that cheap, which way to go is up to you.
    Power supply link below.
    Dave. :)


    The circuit below is an example, the 35 to 40 volts 100uf capacitor can be left out, or drop the capacitance.
    You really need a transformer, or opt for a plug in adapter.
    Last edited: Oct 8, 2011
  5. TBennettcc


    Dec 4, 2010
    In his second post, he asks for a transformer-less power supply. Judging by the wording, he either wants to build a switching power supply, or he's looking for the schematic for one to try to repair a broken one?
  6. duke37


    Jan 9, 2011
    A switching power supply uses a transformer running at high frequency.
    Without a transformer the power loss would be horrendous.

    12V plug-in power supplies are cheap, a couple of these in series would give 24V.

  7. davelectronic


    Dec 13, 2010
    Power supply

    I would not rule out the OP fixing an exisisting power supply, but as for building an smp, i looked at the i am new to electronics bit, and thoght an smp a bit of a tall order, although not impossible, and as Duke said smp's use smaller transformers at a higher frequency input. So a guessed the OP was for 24 volts at a current load of 300 milliamps, so a 1 amp supply would be fine, you can build a psu with no transformer, but at a low current, but a dangerous undertaking for a beginner.
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