official GDIY51PSU Help & Support Thread

[[silent:arts]]

A small observation. As the LM350's were changed to LM317's, the schematic and parts overlay in the 1st post still show LM350. Might confuse a beginner? (Or a simpleton like me :)

Jeff,
nothing changed to LM317  ???
where did you read that?
the LM350 is 3A while the LM317 is only 1 to 1.5A ...
or do you mean LM338 (5A) ;D

 

[jsteiger]

It was some talk between yourself and JDBakker near the beginning of this thread.

A few nits:

With that transformer you're limited to ~1A on the main rails. Why use an LM350 in that case, instead of the more ubiquitous LM317? It looks like you're limited by dissipation not max current, and the thermal resistance of both parts is almost the same, limited by their TO-220 package.

the PCB is designed to power up one Rack, with 12 modules installed needing the max power of all 5 rails.

With a 2x16V/1.5A transformer this PSU can only power eight normal 500-series modules (@130mA max per rail). You'd need at least a 2x16V/2.2A transformer to feed a dozen.

Am I missing something here?

JDB.

And your reply:

With that transformer you're limited to ~1A on the main rails. Why use an LM350 in that case, instead of the more ubiquitous LM317? It looks like you're limited by dissipation not max current, and the thermal resistance of both parts is almost the same, limited by their TO-220 package.

LM317 & LM350 are pin compatible, no problem.

With a 2x16V/1.5A transformer this PSU can only power eight normal 500-series modules (@130mA max per rail). You'd need at least a 2x16V/2.2A transformer to feed a dozen.

will change the transformer specs and my order

Am I missing something here?

you just have the better knowledge

thanks for the nits
(and, btw, thanks to Harpo who helped with this PSU too)

FWIW, I noticed that Ptown includes LM317T's in his parts kit. That's what made me think about the posts.

I guess this was not changed huh? I didn't check the specs of each. I suppose I should have before just populating.

Best, Jeff

 

[[silent:arts]]

Jeff,

the great JDB was talking about my first prototype transformer specs.

we changed the transformer specs for a higher and JDB compatible current draw.
[written like: "will change the transformer specs and my order"]

no problem with any half populated rack, and I'm even sure you can run two racks with one PSU
(depending on the modules).
but JDB is right with "if you spec 130mA each rail it should be able to do it"
never seen a module with 130mA at 4 rails, but you never know ...

 

[jsteiger]

Hey guys,

I thought I would post a few pics of Cemal's prototype PSU enclosure. The final production version will be a little bit different but this will give you all an idea of what's in store.

I need the shoulder washers yet for the LM317's and a cover for the 2nd output connector. Other than that, she's pretty much ready to roll.

The phenolic base for the transformer is only for the proto case. Cemal will have an addition support for the toroid built into the production case.

Also, Volker and Cemal have came up with a nifty little circuit & PCB to indicate proper functioning voltage rails. Mine is just wired point to point. If the rail is not on or the fuse blows, the LED doesn't light.

The front panel is very sharp looking. The pic really doesn't do it justice.











I haven't gotten to testing under full load yet but as of now, the toroidal transformer is excellent. I hope to get to that tomorrow. The slated delivery will be about 6-8 weeks from now on the transformers. Cemal will have to fill us in on the cases.

Best, Jeff

 

[Echo North]

Awesome!

Great work!  Looking forward to this and the power transformer!

You ever rest Jeff?

Mike

 

[jsteiger]

...You ever rest Jeff?

Like they say Mike, "I will sleep when I'm dead!"  ;D 

 

[[silent:arts]]

Jeff, yes, Cemals Prototype is awesome.

For the fuse indicator PCB I'm still undecided which version is best  :
yellow / red, or green / red 
would prefer green / red, but yellow / red is the better / safer circuit ??? ??? ???

 

[Ptownkid]

I'd vote for green/red....but as long as it shows red when there's a problem...no worries.

 

[jsteiger]

If we're gonna do it, I say green when all is fine and red when it's not. Like a traffic stop lite.  ;D

BTW Volker, safe circuits are for girls! 

 

[horvitz]

Jeff, this looks great!  By FAR nicer than the hacked together little case that mine is in  ;D

 

[jsteiger]

...nicer than the hacked together little case that mine is in  ;D

There is something to be said for a "hacked together little case"!

 

[stereokillah]

after made some work in my new apartement every days i tried to finish my 51x box and psu, hoppefuly i didn't sell it now it's alive.

Haven't see the 51x logo yet it's late

i did some test with purple action and evry sound are great no big noise or auther thing like that.

thank you the 3 friends for this new great project

.
NOw it's the time to have time for used it!!!

 

[jsteiger]

Looks Nice!! 8)

Sure is a lonely looking Action though...

 

[grantlack]

Jeff, yes, Cemals Prototype is awesome.

For the fuse indicator PCB I'm still undecided which version is best  :
yellow / red, or green / red 
would prefer green / red, but yellow / red is the better / safer circuit ??? ??? ???

sure, safety's nice and all... but yellow and red is so much more 51x!

green and red would make me think 51x-mas 

 

[Ptownkid]

green and red would make me think 51x-mas 

HAH!

 

[Ptownkid]

So what do we think here...is it realistic to think that a rack would need more than 1.5A per rail? Should I switch out the 317's for 350's in the remaining kits?

 

[jsteiger]

Well, Volker's schematic does show LM350's. I think that is what they should be. It is quite feasible to think that a user will power 2 racks with one supply. FWIW, I am gonna swap mine out.

 

[Ptownkid]

Ok, done...man this run is gonna break me, hahaha. S'ok, I'm more concerned that people get what they need than anything else.

 

[[silent:arts]]

sure, safety's nice and all... but yellow and red is so much more 51x!

green and red would make me think 51x-mas 

;D ;D ;D
now, this is a decision!
we want it 51x, not x-mas!!!

 

[jdbakker]

It is quite feasible to think that a user will power 2 racks with one supply.

Only if they like the smell of napalm molten silicon in the morning (but I've sung a similar tune earlier in this very thread).

I can't be bothered to do the math again, but I suspect that particularly for the 24V rail it's not possible to spec a transformer so that you can safely get 3.2A out of any regulator in a TO-220 package, even given an infinite heat sink. Keep in mind that you need to account for low line and high line conditions, not to mention component variations.

JD 'dissipation!' B.
[besides: compare the price of an extra power regulator board to that of even one typical 500-series module. The big expense is in copper and aluminium, not silicon and epoxy; you can use one (big) transformer to power two regulator boards, and two smaller heat sinks tend to be cheaper than one big one]