Cheapest SMPS Circuit Using MJE13005

The explained circuit in this article is probably the simplest and the cheapest, since it employs minimum number of components and the making of the circuit is very straightforward.

Generally SMPS topology involves some fixed standard stages and criteria. Thgey may be listed in the following manner:

The first stage which is the input stage incorporates an obvious mains rectifiers stage, followed a few important protection components.
The above protection components may be in the form of an MOV , or an NTC or both of these for suppressing high voltage transients.

The next stage involves a mosfet based IC in conjunction with the primary of a small transformer for generating the required oscillations.

The IC is normally a state-of -the-art chip having many in built features and abilities.

Further on the secondary of the transformer is clamped with the mosfet IC through a optocoupler which takes the responsibility of controlling the output voltage to a predetermined fixed level.

However the proposed circuit of a cheapest SMPS circuit is rather free from all these complications and employs a very simple configuration.

The input does not involve any protection, which is rather replaced with the snubber network around the transistor. Moreover the rugged MJE13055 is assumably strong enough to take on most the situations.

The two winding on the primary side are so arranged that on switch ON the circuit immediately starts oscillating at around 100 kHz.
The secondary winding typically decides the output voltage and here no optos or zeners are introduced for the sake of simplicity.

Having said that, the circuit  may be considered quite crude and therefore in some way might be vulnerable at some point of time in the long run.

Here’s another identical  simple 220V SMPS circuit design you would like to investigate:

45 Replies to “Cheapest SMPS Circuit Using MJE13005”

  1. Very interesting circuit idea for hobbyists! thanks in advance!
    I want to know some things–
    1) Output power rating of this circuit- how much mA or Amps ??
    2) please specify the details of the transformer- winding details?? can it be home made with a ferrite rod or torroid ferrite core? plz plz give the wire details!
    3)how much stable this circuit with voltage surge/fluctuations? input voltage range??
    4) can the same circuit design be made with low current Transistors like 13001/13002 etc for making low wattage/power charger or dc power supply?
    5) in place of diode 5402, can two or more IN4007 may be used in parallel?

    1. Thanks!
      The circuit was taken from some other website, I don't remember the exact location…roughly I can say the following:
      1)Power will depend on the SWG of the sec winding, and the inductor size, but cannot exceed above 2amps.
      2)I cannot say about the transformer winding detail, you may consult a professional coil maker. The inductor definitely needs to be done over Etype cores.
      3)This circuit is crude, so cannot guarantee regarding output standards.
      4)13001, 13002 can be used.
      5)1N5402 is more safe and a better option than two 1N4007s

    2. Dear Sir,

      i am working on the 15V SMPS design, as i am interested inyour design Ckt so wanna make 15V SMPS on the same.kindly let me know how can we increase the Output voltage & current on this design as per my requirement.

    3. Dear Ashu,

      Normally by increasing the number of secondary turns results in a proportionate increase in the output voltage, while increasing the thickness of the wire results in an increase in current.

      It's better to use parallel connected wire of two or three instead of using a single thicker wire, for increasing current.

  2. Hi!Thank You for this,it is really simple!Do You maybe know some other SMPS with bipolar transistors?I have a lot of bipolar switching NPN transistors (BLD128,D13009…) and i would love to use them and make SMPS.Most of circuit i find use MOSFET and/or IC.Please help me if You can.Thank You and all best!

  3. don't use 1N series at the output such diodes used for Low frequency rectification….u have to use fast recovery diode like UF5402(ultra fast diodes)…switching frequency of smps is in terms of kHz..mail me if you want efficient and cheap smps circuit design using BJT and

  4. can you explain the working please… i thought that the reservoir cap shud be between the ground and vcc of the primary.(hi voltage section i mean).. but here its btween the vcc and the transistor… :/

  5. Hi,regards.i m designing a 5v 1amp smps can u pls help me to get some idea.i want to charge samsung phone.i opened a samsung charger it consist of 13003 transistor and one 5 pin smd very small part to drive marked another charger it marked in30 and another one marked in70.can u pls help me to make a fast charger

  6. Hello sir,

    I hav noticed the 2nd schema, that it has a bridge rectifier both in input and output, it is in wrong configuration, and also in the collector of the transistor, the diode is reversed biased. Therefore this circuit wont work,

    Sorry, just trying to help.

    1. Hello khema, thanks for pointing it out, both the circuits were taken from some other site, these are not verified by me….yes the bridge configuration looks in the opposite direction for the second diagram, not sure why it's been configured in that way, I found it in one of the forums.

  7. Hi Swagatam,

    I have a query regarding switching can we select or calculate the freq. in flyback topology (upto 100W ) SMPS? I mean to say, in above ckt. which component is used for generating the switching freq.?

    1. Hi Maddy, i can't suggest the formula immediately since I have not yet investigated the circuit deeply… but it's the base capacitor/resistor and the 47uH winding which are basically responsible for the frequency value..changing the value of any or all of these elements could cause variations in the frequency….

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