Patchwork Reloaded: Circuit Optimization and Board Layout.

[MJL21193]

Board layout complete.

[MJL21193]

Originally posted by homemodder

One question though, when you did the last simulations between the 2 did you change both the LTP current source and vas current source or only the vas.

Hi,
I changed both. That was the comparison from the start.

Originally posted by PB2


John, I read you at the start saying that you just want to understand the differences so I am aware that you have no plan to change. I'm just trying to add to the understanding, and throw in my main reason for the CCS preference which is to eliminate the electrolytic cap. I do also wonder why we're not seeing the expected rise in distortion at LF. Might want to try 1 Hz or .1 Hz.

No problem Pete.
I appreciate the points that everyone has made. I see that technically the CCS is the better way, and that the biggest problem with the bootstrap is the electrolytic cap. What I have been trying to do is weigh the harmful effect, and determine if it justifies changing the design. The fact that the cap has a life span and will eventually fail needed to be considered too. The one I have for this is a 100V Nichicon rated for 5000 hours at 105*C.
I think I can expect many hours of trouble free use.
Besides, the way I get sick of things, this may only be around for a year or so.

In the end, I feel comfortable with the choice, and wouldn't have any reservations about doing it this way in the future.


I had a malfunction with my power supply. It seems that the rectifier diodes (1N5406) were not up to the task of charging all of those filter caps. Two of the four failed, and went short circuit. This happened as I plugged the transformer in, and tripped the panel breaker.
SO, I designed and build a new one, with the GBPC25 rectifier. I made the shape different, square rather than rectangular. I think two of these will fit better in the chassis.
Doing things in a rush, i made the fuses a little too close to each other. I have slipped a thin piece of plastic between each.

[MJL21193]

I put some final touches on my new board layout, ready for etching.
My new supply of blank boards is still not here, but I did have a few pieces of double sided left. I used one that was big enough and went ahead and etched the board. I have a pretty good system going for this and I only use enough acid / peroxide mix to do one board. I then discard that mix. I have tried to re-use it in the past, but it has lost all of it's potency. Better a fresh batch every time.
For trace repair if needed, I use a paint marker. I gave up trying to find that magic Sharpie that this mix will not eat. Paint marker works beautifully, dries fast and is absolutely impervious to the acid mix.

[andy_c]

Well John, nobody can accuse you of wasting time!

[MJL21193]

I have taken to putting the component values on the board "silkscreen" - it saves a lot of time and prevents mistakes.
My first try doing it, I made the font too small and it wound up being next to useless. Here I have values that are easily read.

This is the finished board. Hopefully I didn't frack something up.
Trust in my relatively good luck when it comes to this.

[MJL21193]

Originally posted by andy_c
Well John, nobody can accuse you of wasting time!

Hi Andy,
No, I'm full speed ahead when I'm ready and properly motivated. I'll get this one done and if all goes well, I'll get bored with it again and start another project.

No, I'm in this one to the bitter (or sweet) end. Six of these, 2 homemade serious heatsinks, another one of those dinky power supplies, chassis, etc, etc...

I'm assembling the board now. It is the best I've done so far - everything fits as it should. Pics to come.

[MJL21193]

Assembled, but not tested. I thought Id get a couple pics before I smash it with a sledgehammer when it doesn't work.



The bottom:

[jaycee]

Your boards look amazing for a home brew! What method of transfer do you use to get the image onto the board? Is the silkscreen done by laser toner transfer?

[ostripper]

Bravo, MJL, good to see such progress.

What zoble/inductor will you use? (don't see one on board)

Very good reading this thread, bootstrap Vs. CCS,
can now understand how both play out electrically
and harmonic wise.

hope it works..OS



PS..Don't smash it mail it to me .We are all broke/poor
in US

[jaycee]

Originally posted by ostripper

PS..Don't smash it mail it to me .We are all broke/poor
in US

So are we here in the UK