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Cheapest SMPS Circuit Using MJE13005

Last Updated on by 56 Comments

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.



Circuit Description

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:

 

Reader Interactions

Comments

  2. I made the circuit of MJE13005. but the transistor is heated up in no load condition and after 10 min transistor burns out and the also some other component like rectfier etc are also damaged but the out voltage at starting time is arround 13 volt

    Reply

  3. Dear sir the output is not isolated form the main if we want to isolate secondary using pc 817 how will we connect it with feedback winding and secondary winding ???

    Reply

    • Sheraz, the secondary is perfectly isolated from the primary….do you mean the primary is not linked to secondary for output control? you can do it by referring to other similar SMPS designs and by replicating the opto section

      Reply

    • thanks sir. I have design an SMPS circuit for 12V, 2A as the design above you referred. but one problem with the output is that the output change with
      changing load and the 2nd is that the output current of the transformer is not 2A but is less than it. i have used N0 = 84T(28SWG) for primary, N1 = 12T(28SWG) for feedback and N2 = 13T(25SWG) for winding the transformer. how can i get the required 12V, 2A with the above design?

      Reply

      • Sheraz, current can be improved by using bifilar winding method..in this method instead of a single thick wire, many thin wires are wound together compactly. this allows better and efficient magnetic and current absorption…so you can also try this. instead of using single wire, use many thinner wires together and wind them tightly with the same turn numbers.

        Reply

  5. Hi Swagatam,

    I have a query regarding switching frequency..how 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.?

    Reply

    • 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….

      Reply

  7. Sir, i want to make smps with +12V, gnd & -12V. Is that possible? & if so, how to build the circuit? Plz provide me the circuit diagram…

    Regards,
    Mandar

    Reply

  11. 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.

    Reply

    • 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.

      Reply

  12. 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 13003.it marked rf27.in another charger it marked in30 and another one marked in70.can u pls help me to make a fast charger

    Reply

  14. 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… :/

    Reply

  15. 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 mosfets..arspc8@gmail.com

    Reply

  20. I have constructed the circuit.checked well. unfortunately MJE 13005 is heated up heavily. No output is detected.

    Reply

  21. 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!

    Reply

  26. 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?

    Reply

    • 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.

      Reply

    • 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.

      Reply

  27. Hi Swagatam,

    can you list all the components? its hard to read in the circuit diagram.

    thanks and regards,

    Reply

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