The most versatile preamp EVER

[michal_k]

there are two additional small pads per doa socket, it's just too easy to use a piece of wire IMO, anybody?

 

[riggler]

Hey, how about horzontal and vertical index markers? So you can be like:

C7, M42 ....

"you sunk my battleship!"

 

[[silent:arts]]

Now, a thought. Should V+/gnd/V- be run to the DOA pins?

no. don't over-engineer - there might be people without DOAs, there might be applications where you want to have a resistor or anything between the lines and the DOA, there might be one at +/-24V and the other at +/-16V, etc.
I like it as it is.

more important, we have to discuss the color of the PCB ;D

 

[okgb]

C7, M42 ....

"you sunk my battleship!"

Ah scared for life Damn advertising
pop up trouble this kind of trouble is lots of fun

what ever the pcb color make sure the screening
is easy to see , some combo's make it hard on us with failing eyesight

 

[Joechris]

Could a part of the board look like this??
http://www.wrighthobbies.net/catalog/product_info.php?cPath=40&products_id=142
So much easier to make projects with normal opamps...

 

[Igor]

Just saw this, good idea. Farnell p/n's: 149318 and 1336236
for DOA pins/sockets.

 

[haima]

michal_k - I like where this is going! Very useful...

Do you think you'll offer these for sale yourself?

Or perhaps you could "open source" it - and they could be offered through a few people's stores? Like Gustav / Jeff / Volker etc - for world wide distribution?

Thumbs up either way.

 

[evm1024]

I would really like to see this board and a metal bracket that fits 500/51x racks. I wold buy a few.

--EThan

 

[[silent:arts]]

there are already L-Brackets available:



since you have to drill some holes in the front the 4 holes for holding the PCB shouldn't be a problem

 

[michal_k]

Hi guys, quick update. I'm currently investigating possibility of adding some pads to accomodate the most popular transformer footprints. I'll let you know if it works out in several days.

here's what I got so far:
OEP - footprint fits,
Lundahl - footprint fits except of the "small size" ones. PCB hole diameter is 1.5mm - will need some drilling.

EA2622 and cinemags - will need to add some pads. it will be probably possible to fit small size lundahls in this footprint.

 

[dmp]

I"m not sure about transformer footprints. There are too many options I think.
I do think it would be nice to have a breadboard style of tied pads, like Joechris linked to. Not so much for using opamps, in my opinion, but easy tie points for making connections.

 

[geoff004]

I agree with not having transformer footprints.  Allocating spaces for specific things make the board less useful as a blank slate.

Keep it simple.

 

[michal_k]

Including most of the popular transformer footprints would be a waste of space as it turned out(and as you guys said before ) I managed to put cinemag footprint loosing just 4 pads though. Also, pads for third DOA were removed - I don't think anybody would use them anyway.

I think we may call it a final version now, although I always look for your suggestions:

Now I need to figure out what quantity should be ordered. 20 pieces?

 

[haima]

i think if the price was right you'd sell a lot of these.

i.e. i'd buy a couple if they are expensive, but if they are cheap i'd buy ten.

maybe find out what kind of price breaks you can get and let us know - that way we could all chip in to get the numbers up so it's cheap for all?

BUT perhaps get a prototype or two before you order hundreds!  ;D

thanks for doing this btw!

 

[michal_k]

i think if the price was right you'd sell a lot of these.

i.e. i'd buy a couple if they are expensive, but if they are cheap i'd buy ten.

maybe find out what kind of price breaks you can get and let us know - that way we could all chip in to get the numbers up so it's cheap for all?

BUT perhaps get a prototype or two before you order hundreds!  ;D

thanks for doing this btw!

I've just ordered a prototype to check if I got all the dimensions right. Can't really estimate the price now, because I've never done 'large' runs of pcbs(like over 3 ). I'd like to keep the price as low as possible. I think we don't need silkscreen for that board for example.

 

[[silent:arts]]

no silkscreen necessary (where & what would you print anyway?)

calculating a "large" run is difficult ;D
my 51x Card Edge Proto PCB Adapter for example (Jeff and me shared a run of I think 200):
Jeff is nearly out of stock, I have sold 5 or 10
it is either his online store, or the US market

if you don't want to have any financial risk you could ask Gustav to stock them.

 

[michal_k]

Would you mind sharing where did you send your PCBs to manufacture? Same companies as prototype runs?

edit: I don't think I'll be stocking them. Group buy may be the best option.

 

[haima]

it is either his online store, or the US market

i think you need to get your store up and running volker!! 

for me, i find the jeff's online store very handy - i'm from australia, so it's not just people from the US (although i'm sure that's a big part of his market).

i guess it doesn't hurt that jeff is a charming fellow to boot... (not to say that you aren't a charmer also volker ;D)

 

[[silent:arts]]

Would you mind sharing where did you send your PCBs to manufacture? Same companies as prototype runs?

I use www.pcbcart.com
since one PCB is nearly the same price than 10 PCBs I always have a lot of prototypes ;D
you will need Gerber files.

don't forget the shipping costs and import taxes / VAT in your calculation

i think you need to get your store up and running volker!! 

sure ;D
but first I need to sort out my problems with PayPal & MasterCard.
an online store without payment service is unnecessary

 

[Harpo]

I think we may call it a final version now, ...

... if the shown pcb is bottom view, else DOA footprint is upside down.
What about adding the missing 7th DOA pin for adj. if someone wants to fit a real 2520,
might make it more universal.