Basic 3-30V 30A hand made PSU (Kiriakos project back in 1991)

[Kiriakos GR]

This project is something which I made in the age of  23 years old, but even today that I am 44, I still think that it is close to perfect regarding quality of materials and over all design.

It is an adjustable  3-30V 30A Power supply which originally made for feeding with it one 250W FM broadband linear with 2 x MRF317.
 
For about 10 years I was involved with broadcasting in FM band, and also with the assembly of such equipment as PLL transmitters and antennas.
After walking away of this broadcast radio hobby, I did get involved a bit with the citizens band  at 27MHz.
When served as soldier in the Greek Air-force at 90s, I become an operator of 6MHz equipment (Racal radio) etc.
And later on as freelancer repair man, I got involved in setting and repair VHF communication system for boats. 


The concept is simple,  there is an 3-30V circuitry with one 2N3055 as output transistor,
that drives 8 X 2N3772.

There is a 40A metal bridge (rectifier)  and  4 X 15.000mF at 50V

All those transistors (output stage) they are connected in parallel, and its one haves an 15W resistor
so to balance the inner resistance of the transistors ( they must be 0.22 Ohm).


This PSU is even today a performer, and I have even manage to use it so to power up the starter of my motorcycle that requires about 42A at 14V.

Enjoy the pictures.

[Kiriakos GR]

Yes it is heavy.   

[giorgos]

I would say that your power supply is a real "monster" Too much power... Remarkable construction.
My DIY power supply has much less power than yours, but rather enough for my requirements.
I made it back in 1993, and it is based on a well know kit circuit. It has adjustable voltage from 0-30V and current with limiter control from 0 to 3A.
Originaly I mounted it in a rather square aluminium box , and I added  analog panel meters , switch, knobs etc.
Also I used letraset letters for panel artwork, and metal clear vanish for stabilize them.
In 2008 I made some improvements . Firstly I changed the box, I choosed one slimmer  than the old.
I changed panel meters with digital ones, so I puted inside an extra mini power supply circuit for them.
I made some modifications to the circuit like second voltage potentiometer for fine adjustment,
also I put a buzzer in paraller with overload led, something useful because now it doesnt need to observe the overload led indication, to see if the current exceed the limit you have set. You can only hear the buzzer for it so you can focus exclusively  to your work.
And at last I made a front print with "front designer " Abacom software . I print it in premium hp photo paper and after this I sprayed it with clear vanish for resistance in time,humidity etc. The results was fine and after this I adopted  that method for my next DIY projects.

[Kiriakos GR]

Also I used letraset letters for panel artwork, and metal clear vanish for stabilize them.

Very recently discovered that the commonly used word in Greece as letraset which even me I though that is some sort of branding, it is actually the words : Letters Set ... Therefore our word is a chopped down version of the full description in English.   

Working with the clear varnish it is an major adventure, it takes over 9 hours to dry, and if you are lucky you will not have any insect attached to it.
The smell and the power of the chemical composition it is strong enough so to knock them down.   

By the way I have also this PSU assembled too.
The current limiter makes a funny noise when engaging (sort of whistling at 6 KHz).
Those days I am using it exclusively as battery charger for my motorcycle.   

[Kiriakos GR]

Here it is an interesting update 
Recently one customer of my liked my PSU that much and asked me if I can make one also for him.
I did accept the challenge and at that point I have all new parts needed for this project next to me.
And I thought to share few pictures of them.
 

[giavra]

Very nice i'm looking forward to see it complete

[Kiriakos GR]

This is currently my active project, and by estimate I will need 4~5 days to finish it.
Metal case this is used one and a choice of my customer, either way my own internal job (assembly) will be at high standards.
Yesterday I did verify good operation of voltage control circuitry.
Today I will start preparation of front panel and back panel.

[Kiriakos GR]

Last set of pictures from assembly phase of this project.

75% of my puzzle this now completed. 

[Kiriakos GR]

New PSU this is now tested and ready for delivery. 
My own friend and customer he did fall in love with it, design and quality far from his own expectations.

My first ever made one, I did it at age of 21 years old, with minimum use of specialized tools.
If recent version this looking significantly better as build, this is due advanced craftsmanship skills, that no copycat can have or buy.


Last pictures:
a) New 20Kg of electrical power
b) The artist ... with 30 Celsius indoor at night.  (June 23 2017)