[cobaltmute]

As I'm part way through my build of my Pimeta and with no BUF634s in sight almost anywhere (and the one I can find are SMT), I'm looking at using the Monofied Sijosae buffers

Now I did try to build one on perfboard and while it is ok and likely usable, I'm not at all happy at how it came out (especially the long trace across the board).

As a result, I'm think about using BatchPCB to build a set or two of boards. The layout that I've done looks like this:

Now is there anything anyone sees about this layout that is goofy? This would be the first PCB I've ever sent out to production so I want to get it right. Red Traces are bottom, green is top and trace width was set to 50 mil (with the sofware set to allow narrowing of traces)

 

[Pars]

Is there a reason you aren't just going to home etch some of these using mono's pattern? These boards are so small (about the size of a DIP-8) and single sided that getting them run by a board house would require that you do many to make them economical. Home etching is really quite easy if you have access to a laser printer, and iron, and some simple etching chemicals. And a drill with a small (#61 or so) bit.

Easy PCB (Printed Circuit Board) Fabrication, Using Laser Printer Toner Transfer, with a Household Clothes Iron and Glossy Inkjet Photo Paper; DIY at Home; Better AND Cheaper than Press-n-Peel ( PnP / P-n-P )! Making, Cheap , Economical , fastest fas

Regarding your board layout: this is so simple that going 2-sided is kind of a waste. And I hope you were careful in moving things around so that the pins that need to go into the buffer DIP-8 socket (pins 3-4-6-7) are lined up correctly, as they are on Mono's pattern. If you want to proceed with this thru a board house, a single sided 160 x 100mm panel from Olimex might be the most economical. You would need to check to see if they have a minimum board size, but they allow you to fill up the panel and cut them apart for you.

 

[DolbyR]

Would the Sijosae buffer work, (and how good/bad) as a replacement for OPA2134 in the SOHA output stage.
I know Jisbos is out, and its the way to go for SOHA, but until I finish the remaining pending projects, this one looks quite interesting.

 

[cobaltmute]

At the end of the day, I was figuring the price at BatchPCB has ($2.5/sq inch + $10 setup + mail to me) was a fair deal, considering that that is for double side board with double side silkscreen. As the boards are are ~.35 sq inches, cost would be low.

I laid out the required part/pins in the PCB software at the appropriate spacing and then locked them so they would not move as I placed everything else.

I would only keep double sided if I actually sent it out to made. In part doing it was to keep roughly the same wide trace for all the traces.

I was considering toner trace until I learned about BatchPCB. Given that I have no etching supplies on hand, getting it made with soldermask and the likes seems a good trade-off (but then again I don't have the practical of actual having made my own board)

 

[Pars]

If you can get them made for a reasonable price, then yes, boards with soldermask, etc. are nicer than home etched. Does BatchPCBs pricing include cutting the boards to size? WHen I etched mine, I used a large paper cutter (2' blade) to cut them, and it was still a PITA.

Your trace widths are wider than they need to be.

 

[rds]

Someone should do a big run of these. It would be a nice item to have available.

 

[cobaltmute]

What would be a good trace width? I've got it laid out single sided as with about 15 mil traces as well.

 

[cobaltmute]

Quote:

Originally Posted by rds /img/forum/go_quote.gif Someone should do a big run of these. It would be a nice item to have available.

If we agreed on a good layout, I'd be willing to get a small run done.

BatchPCB uses Golden Phoenix to do the boards. error401 made comment in another thread that they are reasonable quality. From what I see there, we could get them made for about $0.60US/board. The only thing is if they charge a setup fee or similar that is not listed (or hidden) on their webpage.

 

[Pars]

I don't have an absolute value in mind, just a bit smaller than what you used to allow a little cleaner routing. I typically use something around 1mm or 0.040" for home etched boards in Eagle.

 

[cobaltmute]

If we wanted it small:

.5" x .6" dual layer, 20mil traces. The dual layer here is simply to avoid having to go "around the edges" of the board on the two traces which makes the board a bit smaller.

As a note, all the pin spacing is on .1"

 

[NelsonVandal]

It's funny no-one has made boards like this to sell. A group buy ought to be a success.

I wonder if there's anything to gain from using transistors instead of diodes, eg 1N4148 like in LISAII for instance. The board could be made smaller with diodes. I think the story is, Sijosae had a lot of BC327/337 and used them as diodes instead of buying new parts.

I've made a lot of discrete buffers on perfboard, even smaller

, and I prefer the standard "diamond buffer" with emitter resistors like the one below. It could be a bit tricky to add 4 extra resistors on a PCB though.

 

[MASantos]

Quote:

Originally Posted by NelsonVandal /img/forum/go_quote.gif It's funny no-one has made boards like this to sell. A group buy ought to be a success. I wonder if there's anything to gain from using transistors instead of diodes, eg 1N4148 like in LISAII for instance. The board could be made smaller with diodes. I think the story is, Sijosae had a lot of BC327/337 and used them as diodes instead of buying new parts. I've made a lot of discrete buffers on perfboard, even smaller , and I prefer the standard "diamond buffer" with emitter resistors like the one below. It could be a bit tricky to add 4 extra resistors on a PCB though.

*cough* go with SMD *cough*!

 

[synaesthetic]

Quote:

Originally Posted by rds /img/forum/go_quote.gif Someone should do a big run of these. It would be a nice item to have available.

Agree. Especially considering the paucity of BUF634P.

 

[cobaltmute]

I'm going to do a BatchPCB run for a couple of boards.

If it works out, I'll do a full panel of the second layout I posted.

 

[rds]

In my mind the diamond buffer is preferable too.
Either way hopefully a group buy will come together soon.