Golborne Vintage Radio

So, gentlemen, and I think a couple of ladies,
I asked some days ago how to post pics. I have worked it out I think !!!.
Starting today, I am building a power supply for an amplifier ( audio ), that I started a few years ago.
This is a bare chassis, and just shows a tin box with some holes innit.
ANYBODY that says there are four without paint have already been told, YES I forgot them when drilling, ( of course NONE of you are guilty of that, ARE you ? ).
So I will start building today, with some hardware. There are four transformers, four chokes, a few electrolytic capacitors, some GEMOVS
( when I was a lad, they were called General Electric Metal Oxide Varistors ),
There are a couple of 105 volt gas regulators too.
Rectification is via high speed fast recovery sand diodes. As I post my progress I will explain what I am doing, and what most of the bits are for.
ANY and ALL critisism or suggestions will be viewed with interest, and will be taken seriously, friendly banter is welcomed.

Its a 1.6mm thick welded steel box, that is painted in satin black after super etching first.
The circuitry is dual mono, as is the whole amplifier.
There is two of everything, except inrush current limiting relay and timer, and master relay so the lil piddly 2 Amp rotary switch doesnt fry.

Inside the box is painted in flat light grey to make reading of resistor colours and even print on capacitors, is easy for a bloke of my age.
It will be totally point to point, but I will explain as I go.

Best to all

Joe

It looks like you made a good solid start

Tracy

Looks very neatly drilled (or punched!), Joe!

I'll watch with interest.

All drilled Kalee,
Wish I had a turret punch, but then I've nowhere to keep it.
Same as a guillotine, panbrake folder etc etc.
Wife is already very touchy about my "junk ".

Joe

[attachment=22170][attachment=22171][attachment=22172][attachment=22172]
So an update after spending a week in bed with the flu. ( first in probably 30 years )

So the photos have labels/names, but here goes.
Front: this is what you will see. There are two seven pin minature valve bases still to fit for the 0B2's.
The large boxes are the main filter chokes. They are something like 2 Henries at 350 mA, ex equipment from a Royal Flying Doctor base station transmitter.
Rear: this is the back panel. It looks a bit complicated but its very simple really. The top of the chassis is two toroidal power transformers. They are wound in my normal super eccentric ratings.
The iron cores are 360 watt rated, but the traffos are overwound to achieve a mere one Tesla flux density, so they only run at maximum of 218 watts. They incorporate a screen winding of copper foil,
and an external flux band of Mumetal. Hopefully no hum !!!! ( he said, and held it to the light ).
In the centre of the chassis is the mains input socket, containing a master fuse in case something happens to my wiring, or the primary windings of the transformers.
Extreme left and right are standard circular aircraft connectors that will have the umbilicals to the main amplifier. These are rated @ 500 volts and 5 amps per pin.
Four fuses, one each for mains of each transformer, and one each for the secondary HT supply for each channel of the amp.
Top: pretty self explanatory really. The holes drilled in the hold down washers for the transformer go right through the centre of the traffo, through both insulating neoprene washers, and through the chassis.
I have found that even that bit of airflow will mean  "about 20 degrees C " cooler transformers.
The two main electrolytics, each consisting of an F&T dual 100 + 100 uF 500 volt working.  One each will be after the rectifier, then after the filter choke. There is another identical cap in each channel of the amp itself to restore decent impedance  after the loss in the umbilical cords.
Under: self explanatory again, but front panel has the neon pilot lamp, and the on/off rotary switch.
Moving to the right we have the terminals for the completely potted chokes. followed by the terminals for the caps and the bias supply transformers.
These actually run backwards, I will feed them a dedicated 12 volts from the toroids into the 30 volt secondary, and use the primary to supply my power to the regulators, and hence  the amp with bias supply for the output valves.
The rest of the mess is flying leads from the transformers and the wires that connect to the aircraft connectors.
All I have to do now is wire it together.

Some will notice four tall brass standoffs that will hold the turret tag strip containing bits n pieces of the PSU, diodes, minor caps and resistors etc. I still have to make that up, but its in my head being designed by the other me.
I try and lay these out to acheive minimum lead length and avoid any cross over points that would bring my minus 105 volts close to my positive 425 volt HT. I dont need push the envelope for the wire ratings.
Wire will all be 24/.2mm standard switchboard wire, as is the standard in Australia. So its rated at 250 volts AC and 7.5 amps current. It should be adequate. Maximum current is the heaters for the 5B/254's running in series, which adds up to 1.8 amps for each channel. Nothing too outrageous.

All comments welcomed, and ANY suggestions to improve something I have done. Nothing wrong with trying for perfection. Both in performance and servicability.

Cracking work as usual Joe, one day I hope to see the finished amp.

You will Andy. I had to take a break from it though, I have been working on it for years and sometimes I just run out of enthusiasm.
Many of my projects go this way.

Joe

(01-10-2023, 08:31 PM)joebog1 Wrote: [ -> ]You will Andy. I had to take a break from it though, I have been working on it for years and sometimes I just run out of enthusiasm.
Many of my projects go this way.

Joe

I'm the same way.  My wife says I'm good at starting projects.

On another note, I owned a Golden Ear amplifier years ago that I picked up at a yard sale.  I never got around to restoring it and eventually traded it off for something, I don't recall what.   It was a solid piece of amp, though.