Amp Builder's Co-operative PCB

[nickb]

In general, it occurred to me that there might be an opportunity to buy components as co-operative and save costs. There could be substantial savings on bigger items like test gear.

Anyway, to specifics. Here is a proposal for a "Universal Amp Builder's PCB" that is an alternative to hand made turret or eyelet boards.



It is fabricated on a 15 x 15in panel array of 6 x 5, making 30 boards to a panel with scorelines between them. That way you can snap off custom lengths in multiple of 2.5 in. I got quotes and each board would be around $2.50 if made 20 panels at a time. FR4 double-sided, 1/16in thick.


What's I'd like to know:
(1) Would enough people be interested in this?
(2) Is there anything you would choose to do differently in the layout?
(3) Would holes to accommodate popular sizes of snap-in electrolytics be worthwhile?

Nick

[Steve Conner]

1) Probably not. Once you factor in the cost of the bulk buy organiser's time, and the number of people who say Yes and change their minds later, or generally mess you around, you could make more money with less stress by just ordering an entire panel for yourself and using the time you saved to get a second job in McDonalds.

2) I'd make the clearances between signal traces and ground plane wider, if this is intended for tube circuits. See the IEC standards on PCB creepage distances.

3) Yes, they are a bitch to mount otherwise.

[Bruce / Mission Amps]

Hell, I'd just like someone to teach me how to run one of those damn "free or semi free" PCB programs everyone talks about, and finally, supply a finished PCB file to a PCB company that can just make the darn things from me...

[nickb]

Thanks Steve- I miscalculated the clearances as 0.05" should have been 0.2".

I've redone it and added pads for four snap-ins. 10mm lead pitch seems to cover about 80% of the supply. Waiting for the new quote.

Bruce - the whole problem with the free PCB programs is the cost to make the boards. It's very nearly the same price for 1 or 100. That's why I'm motivated to get enough parties interested in this.

[J M Fahey]

FWIW and as a somewhat related comment, I designed and made for own use a PCB which , by mounting the proper parts, allows me to build a Plexi, a Bassman or an AC50 with minimal component variations.

And can be populated real quick.

Not needed, but I often add small eyelets at wire exit points.

Can be built without them, of course, and in industrial production I would use a PTH double sided board.
But for home/small scale use this is a good compromise.

It can even accept FETs to make an SS version.

[loudthud]

JM, what do you call a small eyelet? 3/32 inch hole? That size is used on the old Music Man amps where wires terminate to the PCB.

[defaced]

Hell, I'd just like someone to teach me how to run one of those damn "free or semi free" PCB programs everyone talks about, and finally, supply a finished PCB file to a PCB company that can just make the darn things from me...

There are a TON of tutorials on Youtube. I became proficient with Eagle, but do to limitations, I have been slowly migrating to KiCAD. Most of what I learned was either from reading the quick start guides that come with the programs or watching tutorials on Youtube. There's definitely a learning curve, but once you have the basics down you can become very effective pretty quickly.

[J M Fahey]

JM, what do you call a small eyelet? 3/32 inch hole? That size is used on the old Music Man amps where wires terminate to the PCB.

Let's turn the old calculator on

Looks like you have "eagle eyes" or something : 3/32" is 2.38mm; I use *slightly* smaller 2.0 mm .

I use Metric sizes for most everything, except for nuts and bolts, where we are .... surprise !!! .... Imperial.
(Whitworth British)

[loudthud]

Looks like you have "eagle eyes" or something : 3/32" is 2.38mm; I use *slightly* smaller 2.0 mm .

I've been working on my prototyping technique. This board is made from plain .062 FR4 with four different size Keystone eyelets. Connections are on the backside of the board with bare wire of differing gauges. It's a single rail 12W chip amp with power supply, zobel and mixed mode feedback.



I wish I had a better source than Keystone. They are getting expensive. The only 1/4 inch eyelets I can find are aluminum. I'd like to use them for board mounting holes.

[J M Fahey]

Love it.
Looks *real* Pro, specially for the mounting brackets.

Problem with eyelets is that they are not practical beyond, say, 50 or 60 eyelets per board.

That said, when I started making SS amps around 1972, I had been making eyeletted board tube amps for 3 years, and was quite proficient at it, so I continued with the old way, even using somewhat large eyelets and fitting 3 or 4 parts legs in each one , "like in tube amps".

Much faster than using "1 eyelet per leg".

[RedHouse]

Hell, I'd just like someone to teach me how to run one of those damn "free or semi free" PCB programs everyone talks about, and finally, supply a finished PCB file to a PCB company that can just make the darn things from me...

Send me an email, I might have something.

[cyclone]

Nickb, I apologize for participating in the blatant "thread hijacking" but those free cad programs are a huge timesaver.

Bruce, if you spend two hours with pcbexpress laying out a fuzzface circuit, you will get it and be hooked. I also have used Eagle for 20 yrs, learning curve is higher so I'd recommend pcbexpress.

Ok, here's a really useful tip: I use frontpaneldesigner to make faceplates, then I discovered that you can make and save your own objects, so I made objects for transformer holes, opt mounts, all the different tag strips I use, pec pots, alpha pots tube sockets etc. and I do all my layouts and drill templates with it. I also use it to figure out the best way to use tolex, draw a rectangle and drop little ones on it and move them around until I get the best yield.

Emachineshop.com if you want to get a gear made or some other hard part, also easy to get the hang of it

[RedHouse]

...Emachineshop.com if you want to get a gear made or some other hard part...

Hey thanks for that link, I often have need of one-off parts and it's a huge pain-in-the-arse trying to get any of the local machine shops to do anything, they all seem to be doing Boeing sub-contracting work, they're not hungry and just don't want to talk to a guy needing one or two parts made.

Have you used Emachineshop.com before?

[big_teee]

Send me an email, I might have something.

You can't just tell, and help us all?
T

[RedHouse]

You can't just tell, and help us all?
T

It's specific to Bruce's post BigT, not really an all thing.

And no I'm not pulling a quadrapedal diprotodont with the old "I know but not gonna tell anyone".