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Can any body help me in making dual 24 Volt 5 amp Regulator??

Discussion in 'General Electronics Discussion' started by pashu007, Jun 25, 2015.

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  1. pashu007

    pashu007

    3
    0
    Jun 25, 2015
    I want to build +24-0- -24 Regulator with current rating 5 amp. Can any one suggest me the appropriate schematic,


    Thanks
    Prashant
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    11,513
    2,651
    Nov 17, 2011
    Have you tried Google or any other favorite search engine? There are schematics galore on the internet.
     
  3. AnalogKid

    AnalogKid

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    Jun 10, 2015
    Search for terms like 'dual lab supply schematic', 'tracking bench power supply circuit', and other buzzword combinations. Many results will go up to 3 A because that is a common capability of bench supplies, but increasing them to 5 A usually is a minor circuit tweak and a larger power transformer.

    ak
     
  4. AnalogKid

    AnalogKid

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    Jun 10, 2015
    pashu007 - No one has asked this - are you asking about a fixed regulator (+/-24V only) or an adjustable regulator (zero to +24V, zero to -24V). Fixed regulators are relatively easy to do with3-terminal regulators by following the advice in the datasheets.

    Adjustable regulators are more complex. An important factor is how far down you want to adjust the output. If adjusting all the way down to zero volts is important, that makes things a bit more difficult. If adjusting down to 1.5 V is ok for a minimum output voltage, then adjustable 3-terminal regulators can be used.

    1. Fixed or adjustable?
    2. If adjustable, down to 1.5 V or down to 0 V?

    Just to give you a feel for the complexity of the project, here is a link to a bipolar adjustable power supply. It has a tracking feature that you have not mentioned as a requirement. If you don't ned tracking, modifying this schematic is fairly easy.
    http://groenholdt.net/tag_power_supply_index.html

    ak
     
    Harald Kapp likes this.
  5. AnalogKid

    AnalogKid

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    Jun 10, 2015
    Let's start over.
    What is the input to the regulators? Voltage? AC or DC?
    What is the load the regulator is going to supply power to?

    ak
     
  6. pashu007

    pashu007

    3
    0
    Jun 25, 2015
    Sorry guys.. I was away since last month so couldn't able to reply..
    The thing is that I want to built fix +- 24 V regulator using only LM7824 and LM7924 IC up to 5 amp current capability.
    For input step down transformer and rectifier can be used.
    I found on google that if we use three regulators in parallel then current capability will increase 3 times that is 4.5 amp. but it doesn't work when I tried to build.
    even I used series pass transistor MJ2955 and 2N3055 with respective regulators but it also doesn't worked.
    most imp is I want to build this dual power supply using these(7824 and 7924) regulators only..
     
    Last edited: Jul 15, 2015
  7. Martaine2005

    Martaine2005

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    May 12, 2015
    Hi Pashu,
    Both regulators you mention are only 1 amp max.
    How does stacking three in parallel give you 4.5a? Isn't that 3a?

    If you want 5 amps, you need to start with a 5a regulator.
    If you get a variable regulator say, 1.2v to 30v, put the pot inside and 'set and forget'. I would prefer the pots on the outside so it can be used as a variable psu.

    Martin
     
  8. davenn

    davenn Moderator

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    Sep 5, 2009
    pass transistors are the best way for larger current requirements and when done correctly work very well

    show us the circuit u used for your one and lets see where you went wrong :)


    Dave
     
  9. AnalogKid

    AnalogKid

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    Jun 10, 2015
    I agree with Dave. The circuit using a PNP power transistor to boost the output current of a fixed output positive voltage regulator is decades old and very well understood. If yours did not work, that is the place to start. Please post a schematic that includes the power transformer, rectifiers, and filter capacitors.

    ak
     
  10. pashu007

    pashu007

    3
    0
    Jun 25, 2015
  11. davenn

    davenn Moderator

    13,833
    1,950
    Sep 5, 2009
    @pashu007
    we are still awaiting your circuit and maybe a photo or 2 of your construction
     
  12. Martaine2005

    Martaine2005

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    May 12, 2015
    Yes, there are lots. But you specified LM7824 and LM7924. Both of which are 1 amp max.
    The L78xx series are 1.5 amp. That's what you linked to.
    This is what you specified you must use.
    LM7824
    Martin
     
  13. TedA

    TedA

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    16
    Sep 26, 2011
    Prashant,

    Perhaps you can do what you want with the 7824 / 7924 devices. There are some advantages, and also disadvantages to this approach. I expect you might need 8 to 10 of each P/N to supply your 5A reliably.

    These devices may be paralleled using balancing resistors, but the result is poorer voltage regulation than you get with a single device. This may not matter at all in your application.

    Can you tell us what sort of load this will be used to power?

    And, do you know the DC input voltage the regulators will encounter over line and load variation?

    Unless you get lucky, a transformer to provide the raw DC to the regulators will be by far the most expensive and most difficult to source item in your parts list. The design needs to start there.

    A note on the 1.5A vs. 1.0A ratings. I'm sure there is variation among devices from different manufacturers, and even from the same mfg at different times. However, the parts were originally rated for 1.0A and later re-rated at the higher current value. The same identical product. So I would not count on one actually being more powerful than another.

    Ted
     
  14. AnalogKid

    AnalogKid

    2,501
    719
    Jun 10, 2015
    Attached is the LM7824 datasheet. Page 20 figure 13 has a high current booster ircuit that will do what you want. Figure 14 is the same circuit with added short circuit protection. Also attached is an expanded circuit for much higher output currents. All of these will work with the 7924 and NPN transistors for negative output voltages.

    ak
     

    Attached Files:

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