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 Operation
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:
Comments
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.
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
Hi, I could not find any info regarding the devices in30, in70, so can't suggest much, rather you could try the following design for getting identical results:
https://www.homemade-circuits.com/2014/02/220v-smps-cell-phone-charger-circuit.html
sir i want 24 volt 1 amp ckt in above ckt some suggestion plz..
thnks
Khodal, the above designs are not confirmed ones, instead you can try the following , but you will need to make a PCB for this:
https://www.homemade-circuits.com/2013/10/12v-24v-1-amp-mosfet-smps-circuit.html
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… :/
a filter capacitor may be added after the bridge, the capacitor you are referring to has a different function and is also crucial.
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
In this circuit Please tell me which Component you used for high frequency switching?
the transistor and the associated components.
Hi Kumar,
I am sorry, I don't have the exact specifications for the transformer