Aleph L/P PCB Bulk Purchase?

I was still hoping that Brian or someone would do the output boards for the Aleph 2 project. Otherwise there is just too much hardwiring ........... we're talking about two resistors for each transistor and then wiring from transistor to transistors .....

Another project so soon? I don't know ........ building aleph 2 cost close to $1000 already ....... or are we talking about just getting the new project board done and built it 2 years down the road?
 

BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
Dale,

For the output boards, I like the idea of 3 per board with the easy wiring of two boards together. I made some hand drawings, and I will try to make something on the computer to show what I had planned. RS5 should be fine, and most other 5W resistors are the same size or smaller then the RS5 (an observation just from looking through the digikey and mouser catalogs).

each board has 4 inputs, gate, source, drain and sense. I will draw up a quick layout and post it.

--
Brian
[email protected]
 
Brian and Dale,

This morning, I was checking out Wayne's output board layout on Passdiy website ........ why can't you just use that ....... convert it and send it to the same manufacturer as the Aleph 2 board to make it? I don't know what's the procedure to convert the pdf file or is it possible at all. I'm sure Wayne uses some kind of software to do his layout too.

I also saw a board called the Rectifier Board ....... I guess this is the main power supply board excluding those 4 big capacitors .... what I like about it is that there will be minimal hardwiring and very easy to troubleshoot if ever the amps malfunction .... years down the road .... due to bad parts ...not design.
 

BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
I like their designs, but I think that boards should be made like this:

[IMGDEAD]http://www.prism.gatech.edu/~gte619j/output.jpg[/IMGDEAD]

This way, you can tie one end to the main board, and the other end to another output board. This would allow for easier scalability. If you want to build an:

Aleph 1.2, use 8 boards per channel
Aleph 2, use 4 boards per channel
Aleph 3, use 2 boards per channel, with only 2/3 spaces occupied
Aleph 4, use 4 boards per channel
Aleph 5, use 2 boards per channel

I just made the picture in photoshop, so I have not made a layout, but you get what I am getting at.

For connectors, you just need to connect the sense input to one of the devices, and then the source, drain and gate inputs to all devices in parallel.

Let me know what you think.

EDIT: The above board is for illustration purposes only. I did not fully consider the size of the components, or the spacing of the pads. I would make the spacing greater on the pads for wiring to the boards. Another option for the boards is using 2 - 3W resistors instead of the 5W resistor. This would make the boards smaller and cheaper to produce, and I think that it would allow for a wider choice of options. For the Aleph 2, you could use 2 - 2 ohm resistors, etc.

--
Brian
[email protected]
 
I know it's much easier to put a circuit together when using PCB, don't forget however, that point to point wired circuits sound better.
I used to do all my cicuits on PCBs too and my impression was that p2p wired designs were either inferior or not professional.
Recently I started to wire my circuits whenever it' possible and I plan to do all my Aleph projects that way. I just think it's a better way.
 
Yes, I'm wiring the whole circuit and I'm building at least 6 channels. Aleph circuits are very simple and they ask to be wired. I probably wouldn't p2p A75 front end but Aleph amps and preamps are not a problem. With 3-dimensional circuits the connections are much shorter and there is much less connections (board traces are omited), so the whole signal path is also shorter.
 

WayneS

Member
2002-03-24 11:44 pm
Dallas
gents.....

Making boards is EASY. I talked about it a bit in my article on the Pass Labs DIY site. You just do the artwork yourself for groups of 3 power boards, or copy my artwork for groups of 6 power boards.
Make a couple prints on transparentcies on a laser printer
tape the transparencies together
get your positive resist board, developer, and acid
remember to expose BACKWARDS
use a piece of glass to hold the art to the board and expose in sun for 4 minutes.
develop - usually less than 1 minute
etch - maybe 10 - 15 minutes
drill
solder parts
done.
It'll cost you maybe $20 for the first board and $6 - $8 per board
from then on. My 4 output boards for 2 amps came from a single board actually so they were about $3 each.
Try a small test board first if you're afraid or skeptical, thats what I did.

With all respect, I don't think I buy the "wiring sounds better" argument if you use 2 oz copper for these boards. What is at issue here is mostly resistance and the thicker copper helps a lot here. At these F's, mutual inductance and capacitance at 4 or 5 mm spacing for 7 or 8 inches will be negligible. I also made big fat traces to help out with R so I was clearly thinking about it but my boards are easily good enough compared to P2P wiring.

Look at the www.passdiy.com site in the "aleph 2" part of the gallery for my PCB artwork.

Enjoy...
 
I can draft the layout on Acad but ....

1. what are transparencies? Is that like "stickyback" where it's sticky on one side? You stick two transparencies together to make the trace thicker? If I were to buy the transparencies at the stationary shop, what exactly is it called other than transparancies?
2. how does the sun help to expose the artwork onto the board? It somehow "melt" the artwork onto the board because of the heat?
3. once the artwork is exposed to the board and when you add the "chemical", won't the chemical wash the artwork away in addition to the unwanted copper?

Sorry for the silly questions ....... I can't picture it .... I use to do it by using a special pen but it looks terrible.
 
Aleph L/PPCB Bulk Purchase

Guys,

I tend to agree with Wayne,

Besides the mount of the transistors to the heatsinks has to be well engineered and precise. The board makes this a lot easier na dremoves any mechanical stress on the fets which hand wiring may introduce.

I have zipped a couple of PDF files to Brian which may be of interest to him, one is an adaptation of Waynes driver boards, and the other is a fabrication layout for drill spacing etc.

By the way the positive photo resist boards using either iron on or coated copper clad are quite easy to make if you follow some simple procedures.

regards

Ian;)
 

BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
Output boards will make it much easier for wiring the devices, but I have no time to get them made. If someone wants to take up this task, I will gladly buy a set from them.

Or, if someone wants to simply etch some output boards as wayne sankey described, I will send them a pair of main boards in exchange.

Sorry that I don't have time to organize a bulk order for output boards. Next fall (august/sept), if more people want to get together and do a large alephpcb order, I will get output boards made then also, it is just that i have no time now.

As for the main boards, I talked to them this morning, and I will pick them up tommorrow afternoon. I will try to get them packaged tommorrow night and mailed out on wednesday morning to those who I have received payment from and I have sent a verification e-mail to.

--
Brian
[email protected]
 

BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
heh.. I made a mistake. It should have 3 fets on it. I meant for 3 on each board, so that you use 4 for each channel of an aleph 2.

If someone is going to etch boards, the wayne sankey design would work just fine for my amplifier, with 6 on each board. I just figured that 3 on each board would be better for other people, and I was planning on making an aleph 5 down the road.

As I said earlier if you make boards with 3:
Aleph 1.2, use 8 boards per channel
Aleph 2, use 4 boards per channel
Aleph 3, use 2 boards per channel, with only 2/3 spaces occupied
Aleph 4, use 4 boards per channel
Aleph 5, use 2 boards per channel

--
Brian
[email protected]