Transformerless Power Supply

transformerless power supply


Transformerless Power Supply Circuit

Transformers are indispensable in the field of electronics. But the need for a bulky and expensive component like a transformer can be eliminated in circuits involving low current chips, by utilising the circuit presented here.

In addition to being compact and versatile,this circuit is also low cost and capable of supplying almost any voltage ranging from 3 to 24 volts by selecting suitable component values.The Output is sufficiently regulated.

transformerless power supply circuit

Fig.1. single polarity DC power supply

Fig. 1 shows a single polarity DC power supply.it utilises R1 as a series dropper.D1 rectifies the voltage obtained through R2, while D2  stabilises the output to the specified voltage.C1 filters the output.

PARTS LIST
R1 100K
R2 (see table) 10W
C1 (see table) 25V
C2 0.22µF
D1 IN4001
D2 (see table) 250mW
DS1 NEON LAMP

some ICs require a dual DC power supply.For this purpose, the circuit shown in Fig. 2 may be used.R1 drops the voltage . which in turn is rectified by D1. D2 stabilises the voltage and C2 filters it.The polarities of  D1, D2 and C1 are reversed to obtain a negative voltage.Neon lamp indicates the presence of the mains.

transformerless dual power supply circuit

Fig.2. Dual polarity DC power supply

Values of R2, C1, and D2 Depend on the output voltage required (see table)

Both circuits are capable of  providing 25mA current, They continue to provide the specified voltage even if the mains voltage varies from 195 to 270 volts. Suitable component selection table given here.

Component Selection Table
V Out R2 D2 C1
3V 15K 3V 220µF
6V 12K 6.2V 220µF
9V 10K 9V 220µF
12V 10K 12V 470µF
15V 10K 15V 470µF
18V 10K 18V 1000µF
24V 8.2K 24V 1000µF

The circuit can be used with low current ICs.The circuit has been successfully tested with with ICs like UM3482, UM3484, UM66, UM3561, UM3562, NE555, LM741, LM748 and LM556.the circuit is capable of providing around 25 mA current.

The current supplying capability may be enhanced to about 40-50 mA by using a 5.6k, 2oW resistor as R2. However, this would require the use of at least a 1-watt zener diode.


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20 comments on “Transformerless Power Supply
  1. Lorren says:

    Great article, thank you again for wtriing.

  2. ahmad kassem says:

    hello
    how can i modify the circuit to accept 380VAC and to deliver 0.5Amps

  3. Mayank Shorey says:

    Really big thanks for the second circuit mate. Would simulate it and would let you know the results. 🙂

  4. yagneshbhatt says:

    i want to run 12v DC light bulb into ac 230v AC power supply .. which circuit i had to made for it? can u send me circuit diagram…?

  5. Johny Radio says:

    hi, is it possible to get an amp or more from a transformerless supply? -thx

  6. pradeep says:

    Hey dude,
    send me the circuit for 230 a/c input and 12 dc output with 1 amps current rating please send me the circuit asap..thanks in advance ….

  7. Amnos says:

    Hi! Thanks for the circuit.. by the way,how can i have a resistance of 12k ohms 10W if i have 2 12k ohms 5w resistors? thanks in advance.

  8. mouli says:

    hey,
    i need ckt of 12V 1Amp, is it can modifiable to 1amp current output

    • tiago pereira says:

      no! transformerless power supply is up to 100mA! for this search for SMPS transformerlesss power supply

  9. sjaak says:

    do not do this, it can easily kill you if you make a mistake when connecting N and L.

  10. tiago says:

    can i put varistors, NTC Thermisthor, X and Y capacitors and inductors in input 230VAC for protection?

  11. Mohsen says:

    Hi. Can i do use circuit for the led driver?

  12. Rahman MR says:

    Can I have a circuit for 150-0-150 volt 25 amp for 2500 + 2500 w power amp?

  13. Mustafa says:

    “The current supplying capability may be enhanced to about 40-50 mA by using a 5.6k, 2oW resistor as R2.”
    Is resistor R2 5.6K 20W?…

  14. Gautam Rana says:

    24 0 AC to 24 0 24 DC 5amp supply convert. pls..help..

  15. Arsh says:

    Brother plz transformerless dual 40 volt supply

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