40V dual power supply

Description.

This 40V dual power supply circuit was designed in response to a request made by Michael from Philippines. His application is to power the 150 Watt amplifier circuit published here. I think this power supply design is adequate for the purpose. The transformer T1 steps down the mains voltage, bridge D1 performs the rectification, C1 and C2 does the job of filtering.C3 and C4 are decoupling capacitors.

Circuit diagram with Parts list.

40v-dual-power-supply

Notes.

  • The T1 must be a 230V primary, 30-0-30V secondary, 200VA transformer.
  • All capacitors must be rated at least 63V.
  • C3 and C4 are polyester capacitors.
  • If 8A bridge is not available, make one using diodes like P600A.
Show Comments

77 thoughts on “40V dual power supply

  1. Shajeel

    i want to make -30V t0 + 30V dual regulator power supply so plzz give me some circuit of it if u have…Regards

    Reply
  2. keith

    hi seetharaman, so if I want to change this power supply to a variable one, potentiometers at the output are not enough ?

    Reply
  3. admin

    For using this power supply to power two 150W amp modules slight modifications are required

    Transformer must be raised to 350 VA.
    Current rating of the bridge must be raised to 12 or 15 A.
    Fuses must be changed to 12A.

    Reply
  4. Seetharaman

    Hi Mounica you require a maximum current limitting of 30% of the rated battery capacity that is 30amps (for flat battery of less than 11volts terminal voltage)and normal charging current of 1/10 of the rating that is 10 amps at 12volt.

    Reply
  5. Seetharaman

    Hi Mounica you can use 100AHbattery for operating the UPS but it is not rated to charge it, hence you have use an external charger.
    Hi Adnan When you bridge two identical amplifiers into the speaker of same impedance, then it will give 4 times the rated power. i will email you the details

    Reply
  6. mounica

    Hello seethraman i have APC ES-500 UPS it has 12v 7Ah battery
    can i use 12v 100Ah battery instead of 7Ah
    this 100Ah battery will spoil the ups?

    Reply
  7. Seetharaman

    Hi Adnan my PC is through I will send you by wednesday positively.
    Regarding these power amplifiers they are not Class A type that is conuming constant current, but they are class B type hence as per volume their current requirement vary from few mA to few thousands of mA. hence the voltage will vary from 12 volt to almost the AC supply voltage which is likely to kill all the components hence you have to use a shunt regulator to take care for the full current capability.

    Reply
  8. Adnan

    But Mr Seetharaman if i use 220uF capacitor instead of 120uf capacitor as you told me then according to your calculation it will have to give approximate 9A
    (0.47 X 9) / 0.02=211.5uf apprx 220uf????

    Reply
  9. Seetharaman

    Hi Adnan the max current can be 5 Amps at 12 volts. if you want to increase the output voltage the current will fall down. If you short the output the maximum current can be 5amps only.

    Reply
  10. Adnan

    if use 220uf @ 400v instead of 12ouf what will be the output current @ 12volts?
    and if we want to increase the voltage what changing will required???

    Reply
  11. Seetharaman

    Hi Adnan with 0.47uF you will get 20mA, for 5Amps you require (0.47 X 5) / 0.02 you require around 120uF 400 volt capacitor for continuous rating. check for the availability and price. this may be very expensive comparing to switched mode power supplies which are quite efficient and pretty small in size. 12 volt 5amp Halogen bulb power supplies are available for as low as INR150/- very small 2″ X 1″ X 1″ few grams in weight. efficiency >90%

    Reply
  12. seetharaman

    Hi Adnan if by chance if the output is shorted or load takes higher current as per the capability of the trransformer then the rectifier will get destroyed. hence it is preferable to use higher rating bridge rectifier.

    Reply
  13. Adnan

    if we have 4Amp transformer then we have to use more than 4Amp bridge like 6amp why we use high ampere rating bridge?and what will happened if we use low ampere bridge when transformer current is high??

    Reply
  14. seetharaman

    With 12 amp transformer your short circuit dissipation of the trasistors are 1200 watts 600 at + and 600 at -. That is you require around 20 transistors in parellel on heat sink.
    to reduce the number of transistors a thyristor to be added with suitable zener and transistor, you can make a very compact high current variable power pack. i will send the circuit by next week.

    Reply
  15. Adnan

    if i want to use 50-0-50v @ 12amp transformer in that power supply you’ve mailed me then what changing will be made except of bridge rectifier or will the circuit remain same??????

    Reply
  16. Adnan

    Thank you very much Mr seetha raman for the circuit you solve a big problem for me now after implementing this supply i will be able to power many of amplifier circuit and other circuit thanks again
    i understand all the working of this supply but tell me that why we use too much transistors?what happened if we decrease the quantity of transistor?n tell me if there any replacement exist to decrease the quantity of transistors?

    Reply
  17. seetharaman

    Hi Adnan please bear with me for few more days my desk top is down i am using my mini for just emails no graphics possible.

    Reply
  18. joel

    Hi seetharaman

    i want to reduce this 40v to 12v to connect to pre-amplifier

    how can we reduce tell me please

    Reply
  19. seetharaman

    Hi Adnan you can provide series pass transistors with its base being controlled by variable reference.

    Reply
  20. seetharaman

    Hi Adnan with higher capacity power supply(current) you can always draw lesser current. but not the other way round.

    Reply
  21. seetharaman

    Hi Adnan you have US$1000 in your account hence you can draw easily US$600 from your account.
    You can draw 6 amps comfortably.

    Reply
  22. seetharaman

    Hi Adnan why not for very low currents. for higher current add few series pass transistors.
    Any transformer you can use, out put will be root 2 times the AC input.

    Reply
  23. adnan

    if i have a power supply of 30 volts 12 amp.Is this is possible to get 30 volts 6amperes from the 30volts 12amps power supply??

    Reply
  24. adnan

    p600A diodes can make a 8 amp bridge
    tell me the equivalent diodes for 6 amp bridge, 4 amp bridge and 2 amp bridge diodes name???

    Reply
  25. adnan

    p600 diodes can make a 8 amp bridge
    tell me the equivalent diodes for 6 amp bridge, 4 amp bridge and 2 amp bridge diodes name???

    Reply
  26. seetharaman

    Hi ADnan the capacitor will get heated up and explode. For a 25 volt capacitor 20volt will be safe limit. in some capacitor they would have mentione the voltage at 85deg C. These capacitors can be used upto the rated voltage. if temp is not mentioned in a capacitor, it is to be taken as 25deg C and derate it and use it at one third the voltage indicated. since inside the equipment the ambient may raise to 75 deg C.

    Reply
  27. adnan

    if i give more than 25v to a 220uf 25 volts capacitor what will happen?what will the output or the capacitor will destroy??

    Reply
  28. adnan

    if i have a power supply of 30 volts 12 amp.Is this is possible to get 30 volts 6amperes from the 30volts 12amps power supply????

    Reply
  29. adnan

    if i need 220uf 50v capacitor but i have a capacitor of 220uf 400v can i use 220uf 400v capacitor instead of 220uf 50v???

    Reply
  30. seetharaman

    By increasing the voltage of the capacitor will not have any effect on the output power.
    200va / 60volt is 3.333Amps.
    30-0-30volt transformer, both the 30 volt winding should be capable of giving >3amps current.

    Reply
  31. Jed

    In order for this supply to be used for two 150W amps – left and right – would it be necessary to increase the VA of the transformer – if so – by how much? Cheers

    Reply
  32. Jared Cook

    Would this be suitable for a stereo amp based on two of the 150W amplifiers or would two separate power supplies be required? Cheers

    Reply
    • admin

      two seperate power supply will reduce noise, but it is very costly.
      Here a single power supply with double ratings is enough for stereo mode.

      Reply

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