6A PSU using L200

[Bluechip]

Hi Folks

To amuse Mr. R. Wilson ...  4-6 V @ 6A Regulator. (  ?)

I suppose it's a PSU, as the bridge rectifier is on the heatsink with the transistors ... & whatever ..

Home brew PCB using 'fast etch' facility on mill.  ( It would have been faster if I could remember where I last slung a 4mm slot drill )

2 MJ2955 on t'other side of heatsink ..

2 yellow wires go to the transformer secondary, not really aerials ...



Dave BC

[Rob.Wilson]

Hi Dave


mec it do something   

Lookin good 

Rob

[John Stevenson]

                      BANG

[SKIPRAT]

Hi Dave
Now i know what to do with the L200 regulators i have got three strips of 50 that makes 150 in total .


Cheers Paul

[Bluechip]

                      BANG

Not so far ... one can but hope ...  

Soak Test tomorrow ... full power for 2 hrs. ....

Dave BC

EDIT The PSU, not me, ....

[MrFluffy]

Is this load it up till the big electrolytics turn into party poppers time?

[Stilldrillin]

Hi Folks

To amuse Mr. R. Wilson ...  4-6 V @ 6A Regulator. (  ?)

I suppose it's a PSU, as the bridge rectifier is on the heatsink with the transistors ... & whatever ..

Home brew PCB using 'fast etch' facility on mill.  ( It would have been faster if I could remember where I last slung a 4mm slot drill )

2 MJ2955 on t'other side of heatsink ..

2 yellow wires go to the transformer secondary, not really aerials ...



Dave BC

Dave!

Dave! 

It might amuse young Rob........   


BUT! Worrizit, (PSU?), an wotsit actually do?

Where does the 4mm slot drill fit? 

Am confussed......... 

David D

[Bluechip]

Mr. F.

Yup, probably  

Just re-calculated the ripple volts and the ESR, I'm a bit er ... near the max on ripple current, room for some larger caps. anyway. Just stabbed those two in 'cos I had them ..  Some you win etc.

Dave SD

PSU   Power Supply Unit ..

Your are Confussed .. wasn't he an ancient Chinese Sage  ... long thyme ago ....   ..... got stuffed in the end ??  

Yeah, OK, ... not funny ...  

What does it do  ??

Not depicted is the transformer that has 240Vac in and 7.5Vac out ... down the two yellow wires ..
This is rectified to about 10V DC .. or rectified AC as it used to be known ...
The 'raw' DC is smoothed out by the two capacitors .. the cylindrical wotsits on the right ..
( Unless the little bowgers go phutttt.. and eject their toxic guts in all directions ....  not unknown     )
Having got some DC which will still have some ripple on it, we then purchase (at some £2 unless you are a SKIPRAT it seems ... ) a L200 regulator chip, which is the little black thing with a hole in the metal tab, sitting on 5 legs just inboard of the blue connector, extreme left. Having consulted the .pdf for the L200, which tells you how to deal with the thing, you whack a bit of a circuit board together, the yellowish thing with the L200 on it. And, having ensured the exits are clear, ..
Connect up, and switch on.      
But NO, it works. Rather surprised. Not usually the case.
I use the slot drill to remove the copper off the circuit board. If you make a PCB for a power supply, most of the copper stays on. Saves messing about etching with Ferric Chloride. You can see the places where the copper has been removed, the greyish tracks on the board ..
The output voltage can be adjusted by the doings hanging about on the end of the two red wires .. all done by the L200 ..

That's it .. not very exciting really .. your Big Bertha Stirling much more enticing .. IMHO ..

Dave BC

[Stilldrillin]

Hmmmm....... Thanks Dave! 

That's it .. not very exciting really .. your Big Bertha Stirling much more enticing .. IMHO ..

Dave BC

Enticing? The turbo boost is exciting.........  




Note added lead, to stop it walking! 

David D

[Bluechip]

Hmmmm....... Thanks Dave!  

That's it .. not very exciting really .. your Big Bertha Stirling much more enticing .. IMHO ..

Dave BC

Enticing? The turbo boost is exciting.........  




Note added lead, to stop it walking!  

David D

WOW ... sure you've got enough heat going in that engine ...

I see you've given up on the 'Carbon Footprint' aspect ...  

Nice .... engagingly brutal ... my sort of engine ... jealous ...

Dave BC

EDIT   .. BTW, your pic seems to be minus the little triangle thingy that makes it whizz round ...    any chance ?

[John Swift]

look windfarms are clean and green - until you let the magic smoke out
but our projects are more fun

[Bluechip]

John

I think your pic. needs re-sizing ... pulled the sides off my screen, still can't see it aaaaaaaaaaaall ..

Dave BC

[John Swift]

Yes your right     I've saved a smaller picture
the first picture did not look that big when I saved 

would one mje2955   ( plastic pnp) not of been ok ? or even a 2N3055 ( metal npn )

I've not used the L 200 regulator my self  - thats why I am following your project

waiting for your next instalment

[Stilldrillin]

EDIT   .. BTW, your pic seems to be minus the little triangle thingy that makes it whizz round ...    any chance ?

I`m confused again Dave....... 

Why would the pic need to whizz round? 

If you mean the crank throw. It`s still there......... It all gets a little blurred at a dizzy 400+ rpm! 

David D

[Stilldrillin]

look windfarms are clean and green - until you let the magic smoke out
but our projects are more fun

So true John! 

Love the pic. 

David D

[Bluechip]

EDIT   .. BTW, your pic seems to be minus the little triangle thingy that makes it whizz round ...    any chance ?

I`m confused again Dave....... 

Why would the pic need to whizz round? 

If you mean the crank throw. It`s still there......... It all gets a little blurred at a dizzy 400+ rpm! 



David D

Those funny pics. with 'YouTube' in the botom RH corner, and a grey rectangle with a black triangle in the centre ...

Sort of shorter version of the Saturday Afternoon 'Tuppenny Rush' ..

No Candy Floss tho' 

Dave BC

[Bluechip]

Yes your right     I've saved a smaller picture
the first picture did not look that big when I saved 

would one mje2955   ( plastic pnp) not of been ok ? or even a 2N3055 ( metal npn )

I've not used the L 200 regulator my self  - thats why I am following your project

waiting for your next instalment

John

You could use a ( or more ) MJE2955, but not a 2N3055. Needs to be pnp, not npn.

On this PSU input volts is about 10V, lowest output Volts is 2.7-ish. This gives about 7.3 volts across each transistor x ( 3A )... ie some 22W.

With one it's 44W ... I used two MJ2955's to give them an easier time .. I got quite a few anyway. Will also put a box fan on it.

If you download the L200 .pdf and also the L200 Application Notes ( more circuits ), from ST.com it's all in there ..

Would post the .pdf of the Eagle Schematic but I don't know how to 

Don't even know how to post a image ... tried but failed .... 

Dave BC
 

[Stilldrillin]

Those funny pics. with 'YouTube' in the botom RH corner, and a grey rectangle with a black triangle in the centre ...

Sort of shorter version of the Saturday Afternoon 'Tuppenny Rush' ..

No Candy Floss tho' 

Dave BC

Oh..... Them things! 

I get bored wi em, after a few seconds of watching an engine whizzing. So, I only take filums of new stock. 


Drive a candy floss machine!  Oh yeah..... That's a great idea! 



Anyhow....... I think we should return to topic. 

Whatever it was ....... 

David D

[Bluechip]

Topic ????   Wot topic ... Choccy bar ??

Nowt to do wi me anyway     

Gone 

[John Swift]

Hi Dave BC ,
 I see you had two good reasons for using the MJE2955's
first you have them all ready and the pin out of the IC makes it easier to use a pnp transistors

you would need to use a pnp transistor with a npn power transistor like the 2N3055 to form a quasi -pnp transistor
like they used to do in audio amplifiers when there was not as many PNP power transistors

the first IC regulator I used was a uA723 , ideal for using with NPN transistors
Its a bit old ( like me ) but because the reference voltage came out of one of the pins and both op amp/ error amplifier  inputs , it was easy to turn the output down to zero

[Bluechip]

John

Never had much to do with discrete transistor audio amps. Built several valve Mullard 5-20's / 5-10's, but the only one I ever built was a ( Williamson ? ) pair from a kit bought by a character in the pub who then decided it was a bit beyond him ...  seem to remember MJ340 or similar. Worked OK for him anyway .. got some free beer. He was happy, I was happy... briefly IIRC...

I don't see why the comp. pair arrangment shouldn't work .. must admit I just modify stuff from the .pdf's.  There is a cct. using a 2N3055 as a pass transistor, don't know if you've downloaded the things .. but it's more involved than the pnp jobby I did. I just paralleled ( ?  spellcheck ) .. the two off with the usual emitter ballast resistors to even 'em up a bit. Not needed if you have a lot of transistors to choose from, and the patience to find a matched pair.. Can't be bothered, just ballast the damn things. QED.

I have used the uA 723, long time ago. At one time it was the device of choice, seem to remember them in a metal can .. might even still have some..

First used the L200 in 1978, a mate worked at a semiconductor/ electronics bits wholesaler. Managed to scrounge a 'developers sample pack of 10 ', never used any other adjustable reg. since then.  Bit inconvenient having to pay for them. Never forgiven him for resigning to go somewhere else better paid. No thought for others, some people ..

Dave BC

[John Swift]

Hi Dave ,
              I can see why you use the L200 regulator , it is nice and simple and the price is right  

variable power supplies I have built in the past could go down to 0 volts and one  had variable current limiting as well
with the L200 chip you need a  negative 3v supply to do that
a charge pump circuit could generate that from the positive supply or use a transformer with a centre tap ?

BTW the wiliamson amplifier was a valve amplifier , I should have the circuit
 have found on the 'net  the circuit of a John Linsley Hood design  that may be similar to your amplifier



           John

[Bluechip]

Hi John

Just looked up the Williamson amp. Too true, it is a valve amp.  So why did I think the one I did was one ??  Another bit of brain shot 

That J. L-H looks familiar, but the output transistors don't match my memory, vaguely remember MJ340 for some reason ??

It was only a pair of P.A.'s I built for him, 'cos he connected them to a posh ( Nordemende ?? ) walnut veneer radio-gram. Which had the pre-amps/equalisation stuff in it ...

I don't think there's much that can't be done by torturing a '555. .... 

Dave BC