A collection of my SMPS

  • Mains Transformers
    Mains Transformers, Left: EL-type, Right: Toroidal
  • SMPS-36V out
    A commercial SMPS with symmetrical 36V outputs
  • Homemade SMPS
    My Homemade SMPS with 20V symmetrical outputs
  • Nice Looking SMPS
    Another Commercial SMPS, outputs 26V symmetrical

This is about my SMPS (Switch Mode Power Supply) for the gainclone amplifier I previously have posted. An SMPS differs to the conventional linear 50Hz power supply (pictured below) in that it converts mains voltage using a smaller HF transformer. This small size is made possible because the current is switched (or turned on and off) at more than 40kHz or 40,000 times a second by a pair of switching transistors or MOSFETs. Contrast this to the 50Hz frequency of our mains applied to the linear PSUs. It is then clear as you go higher in frequency, transformer size decreases. Further information is available at Wikipedia here if you want to know more.

Mains Transformers

Mains Transformers, Left: EL-type, Right: Toroidal

All the SMPS’ I have below accept 13.8V input from another SMPS powered from mains, and output different voltages for the amplifier. The first one below outputs symmetrical 36V to the gainclone, capable of 16A max input current using a small toroidal transformer, which translates to 220 watts of power.

A commercial SMPS with symmetrical 36V outputs

A commercial SMPS with symmetrical 36V outputs

Another one below is a home-made SMPS that I created a few years ago. I used this one for my other amplifier, a bridged TDA7294-based gainclone I made specifically for my subwoofer because the former requires low supply voltage of 20V CT. Notice that this one uses an EL type transformer and four pieces of high speed rectifiers. I salvaged them from an unused PC power supply circuit, and rewound the transformer from scratch. This little one has proven dependable and reliable even for a demanding load.

A Homemade SMPS

My Homemade SMPS with 20V symmetrical outputs

I have another commercial SMPS below. This one outputs 26V CT voltages, but with a smaller rectifier diodes with a maximum rating of 3A. The small rating makes it unsuitable for use on fast-transient load. Nevertheless the big toroidal transformer along with its thick enamelled wires make for a nice looking SMPS 🙂

Another Commercial SMPS

Another Commercial SMPS, outputs 26V symmetrical

Edit: Having been abroad since a few months ago, all of those PSUs now became abandoned in my storage box because no one in my family knows how to wire them 😀

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  • Eko

    Does this high frequencies made any bad influence (hum / noise / interference, etc) to the GC amps?

    • No, the high switching frequency will not influence the amps in any way, at least not in the audible range of human hearing (20Hz-20kHz).

  • Swati

    Thanks sharing this post, it’s really nice and consist lots of information in this blog. http://connectwell.com/global/products/switch-mode-power-supply.aspx?lang=en&reg=in