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Wednesday, 30 March 2016

Power supply bodge

I have a couple of torrid transformers with some big 6A 9V AC windings.

I want them as 3A 13.8V static supplies.

I had thought about rewinding the secondaries but the simplest (read cheapest) option looks like something from eBay.

The description (warning Engrish used!)

Module Name: 150W boost module
Module Properties: non-isolated step-up module (BOOST)
Input voltage :8-32V
Input Current: 16A (MAX), if the current is larger than 8A, please add extra heat dissipation.
Quiescent operating current: 15mA (12V liters 20V, the output voltage higher the static too current will increase)
Continuously adjustable output voltage :9-46V
Output current: 8A MAX exceed 4A enhance heat dissipation (input, output differential pressure, the smaller the greater the pressure differential output current)
Output power: natural cooling 90W, to enhance heat dissipation 150W
Operating temperature: -40 to +85 degrees (ambient temperature enhance heat dissipation)
Operating frequency: 380KHz
Conversion efficiency: Up to 95% (the efficiency of the input and output voltage, current, differential pressure related)
Short circuit protection: None
Input reverse polarity protection: No, (if required in the input string into the diode)
Installation: 4 3mm screws
Free welding output wiring: terminals, with housing for welding output. (V-IN is input as an output, V-OUT)
Module size: 60(L) x 50(W)x 20(H) mm
1, DIY a regulated power supply, input 12V can the output can 12-46V/60V adjustable.
2, the power supply for your electronic equipment, can set according to your system voltage output value.
3, as the vehicle power supply for your laptop, PDA or digital products supply.

I expect I will have to add some filtering to the output as this will create some hash (quick test shows it does) but nicely RadComic a few months back showed some simple common mode filters that will do the job. I have a load of sub 1MHz ferrites just begging to be pushed into service.

The pcb even has the cable points for a fan so might dig out an old CPU heatsink fan and add that. 

So it will look like this...

mains in visa a kettle lead type socket, dpdt switch and fuse, into the transformer, 6A 9V AC out into a bridge rectifier, 10000uF capacitor 16V across the output, into this module, via a common mode filter, out of this module into a second common mode filter then DC output.10000uF capacitor 16V across the output. I MIGHT put a voltage display on the in and the out.
(Description until photos)

I will test to see if need to use a voltage regulator, if I do will be an LM317 and pass transistor.

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