Filament supply modules.

[Andrew]

Great, much appreciated.

Would you be willing to send me the .asc file? Save me copying it into Spice?

thanks again,

Andrew

[Mike H]

In case anyone is wondering that is a latter part of a quick PM conversation we were having lol

[pre65]

In case anyone is wondering that is a latter part of a quick PM conversation we were having lol

What would be the max current of your circuit, like wot I built ?

Would it do 6.3V & 4A ?

[Mike H]

At the moment it only does 1.2A. In theory could do more but a helluva lotta heat will be generated. This one runs bluddy 'ot already and the transformer simmers nicely as well (albeit two circuits for stereo obviously); much more will need mahoosive heatsinks

[Mike H]

For Andrew, think everything is here, if not please say so ~

Uses:
.lib standard.bjt [BC547B]
.lib bridge.lib (+ bridge.asy)
.lib potentiometer.lib (+ potentiometer.asy) [select list group, various values]
.lib thermistor_ntc.txt (+ thermistor_ntc.asy) [group, various values]
.lib tip142.lib (+ tip142.asy) [darlington model, npn]
.lib tip147.lib (+ tip147.asy) [darlington model, pnp]
.lib vregs_7800.lib (+ vregs_7800.asy) [group, various Voltages]

HTH

[Andrew]

Thanks Mike, I've reread the thread and I'm thinking of trying the circuit Philip used as a simple first step, see how much it might drift...

cheers,

Andrew

[Mike H]

Fairy nuff, this might be useful then:

[Andrew]

Today's task was to get one Mycroft module nearly finished. Task completed !!

I have to say that the way I did it was constrained by what I had to hand. After the photo was taken I realised that the 12V regulator was wired to pins 1,2 and 3. It should have been pins 2,3 and 4.

Had to drill a new mounting hole, made me swear when I realised.

RS short shipped me the other regulator so can't get on with the other one till Tuesday probably.

How hot do these get chaps, I'm trying to get an empirical feel for it that sometimes the sums just don't give you. I get about 5 watts on the TIP142.

Andrew

[pre65]

Mine are not too bad, but they are one per mono amp, each with it's own heatsink.

I could make do with a smaller heatsink if space was a problem.

I was looking at the Rod Coleman module PCB's but that would mean new transformers as well.

[Andrew]

I was also wondering if it makes sense to get some of the heat out of this by using an 15v transformer, sort of likes this. Basically I used a lower voltage reg and changed R4 for 1k and opted for a 15v tranny.

Mike what am I missing, it seems to sim OK?

Andrew

[pre65]

I use an 18v transformer but also a 63mH choke so that reduces the volts a bit.

The transformers and chokes were in the spares box.

15v should be fine.

[Mike H]

How hot do these get chaps, I'm trying to get an empirical feel for it that sometimes the sums just don't give you. I get about 5 watts on the TIP142.

Yep.

[Mike H]

I was also wondering if it makes sense to get some of the heat out of this by using an 15v transformer, sort of likes this. Basically I used a lower voltage reg and changed R4 for 1k and opted for a 15v tranny.

Mike what am I missing, it seems to sim OK?

Andrew

Well in my case it also has to work for 801A which needs 7.5V, plus margins for V-reg and current reg Voltage drops.

I went from what was originally 17VAC 1 Amp x2 mains TX onto a RS toroidal 15VAC x 2, 2 Amps each winding or something and like you the supply Voltage was too high with that, so I dropped it by putting a resistor in series with the mains primary so it's more like 12VAC.

[Mike H]

PS: the heat is a problem, the toroidal gets freakin' hot a well, it's even got its own heatsink, well that is to say one on top of the panel where it's screwed on underneath.

In my head I've got an idea for another version which should work on lower Voltage + filament Voltage stabilising feedback, i.e. more like the tentlabs kind of thing, but nowt "on paper" yet.

[Andrew]

Don't say that I was just about to order the parts for this one....

Andrew