[BOSOZ] PCB fot the Audio input Selection board

[zeno]

You can take a project apart at lightning speed...

[Peter Daniel]

I decided to update it recently with Aleph P 1.7 circuits, so I made some pics in a process. Still waiting for its turn though.

[wchick]

Alex,

Thanks for sharing this.

Wallace

[tomchaoda]

Alex:

I downloaded your zip file, but my light EAGLE software can not open the board file. It is saying the file may be damaged! I tried it with 2 machines and they are all the same! Can you verify if the file in zip is good?

Thanks

Thomas

[wijgers]

You should use Eagle 4.03

This should do the trick, No problems opening the file's. I also had problems opening the files, but after searching the internet finaly found the program. Be aware off a lot of cracks wicht you are directed to.

Nils

[lgreen]

I have made a BOSOZ input relay Board, pictured below. It uses 4 Quad NAIS latching relays each which switches the pos and neg inputs for a single channel. This is my 1st DIY in about 15 years so I am new at it, but this appears to work, my preamp will be ready in a month or two.

Its 2"x4" which is really small and there is kind of a wacky layout. Don't hate me! The layout is the best I could do since I am using the free eagle pcb program which limits board size.

This is actually pretty good from a signal perspective (I think, hey this is my 2nd Board so what do I know), and is 2 Oz copper. All unselected inputs are grounded through 100K resistors. The diodes are there to protect reverse emf from hurting the relay contacts, as suggested by an app note I read once.

Inputs are selected with a 9 pin contact.

1. set input 1
2. reset input 1
3. set input 2
4. reset input 2
5. set input 3
6. ground
7. reset input 3
8. set input 4
9. reset input 4.

When I make a selection of an input through a momentary pushbutton switch, a diode matrix (on another board) fowards the appropriate 5 volts to the pins of this board and this board sets the relay you want and resets the 3 other relays. Its kind of foolproof (hopefully) but be forewarned, these relays are expensive.

Oh, and do you see my cool 9 pin mini-DIN connector! (actually its not installed on this board...yet, but you see it in the layout) Yeah baby! I told you I was new at this. Wait till you see my BOSOZ. I am definately dangerous.

Here is a combo-pic of the relay board.

[sianturi]

How much are you guys willing to spend the money for a relay (DIL relays) ?

I recently open the RS components catalogs on relay, and there are some (small current, DIL) relays costing about US$11 !

Also, what characteristics are good for audio purpose?
I've seen some relays with various contact material:

- Ag on Au (silver on gold)
- AgNi + Au plated
- 92/8 gold/silver alloy over silver-palladium contacts
- Ag + Au clad
- AgCdO (silver cadmium oxide)
- etc.

What are the best contact material?

[tomchaoda]

Try this, if you use smaller relay:

http://www.apexjr.com/components.html#Relays

Thomas