6 volt LT at 2 amps

[Refugee]

Are we absolutely sure that the mounting plate for the output terminals is not conductive?
It looks like old brass in the photos.

[unrealdave]

Are we absolutely sure that the mounting plate for the output terminals is not conductive?
It looks like old brass in the photos.

No they are ebonite

[Crackle]

Why not bring it over to my place Dave.

Mike

[Refugee]

I agree about the terminals.
I was asking about the mounting plate that attaches them to the wooden box.

[unrealdave]

Hi Refugee - sorry I wasn't clear before - the mounting plate is ebonite, the terminals are brass with ebonite caps.

[unrealdave]

Hi Mike - thanks for the offer but I have a cunning plan  

Some bits should arrive today and I will show my idea / design for the Romford meaty six volt mean machine later.

I am going to just disconnect the first one and bring it for the next get together along with a club hammer    

[unrealdave]

OK the postman’s been so this will be the plan

Instead of an integrated bridge 4 1N5400 diodes then a 25V 4700uF cap, a new LM338T in a bigger heat sink with R1 at 120 and R2 at 470.  In the same box but instead of using the copper strip type board a chunky ‘whatever it’s called connector strip’ (see pic).
 
If need be the voltage out of the diodes should operate a PC PSU fan if things get warmish

Quick check – on circuit diagrams the diodes are shown as triangles with lines across one tip – I assume that would be the silver marked end on the ones in the pic?

[pwdrive]

Silver ring is the cathode, the cathode is the bar across the tip of the triangle in the schematic.

Lawrence.

[Mark Hennessy]

Sorry, but I still say that's not enough heat sinking, especially if it's inside a wooden box with no ventilation. The diodes will run pretty warm too. A fan might help, but with no cool air coming from outside the box, it will eventually overheat.

That heat sink on the outside of an aluminium box would be ideal.

It might only be around 5 watts or so, plus whatever the transformer chucks out, but shifting that is harder than many realise.

Power supplies are one of my "things", and as such, experience has taught me to be rather conservative.

[unrealdave]

Cheers Lawrence - I thought so

As for keeping it cool I was planning on a grill for the top of the box, with the fan on that.