(the modeling shot)

Basically, an idea is to allows up to 7 devices, in this case (inputs or outputs, don’t matter), to be plugged in and to have them criss-cross connected across ‘busses’, to route the audio signal inputs to desired outputs. The goal is to have a remote, pc, or manual over-ride controlled source/destination bussed audio selector matrix.

Say, you have 2 or 3 pcs, with front and back speaker sets, external radio, to be routed to big room speakers, small personal speakers, headphones, rf transmitter (to listen outside or in other rooms), tv speakers, and such…

Idea is also, to add on pcb’s as modules for either extending the number of inputs per bus, or adding more busses, to have more signals redirected simultaneously. Basically, a switching matrix.

This is prototype test. It works.

some background:

I had plenty of 5v coil relays, and that’s what I decided to use for the project. Yeah, they’re not ment to be used for audio grade, but like I said above, it works…

What’s missing on the 1st built pcb is the 7805 voltage regulator, but since it’s going to be near a pc, and pc ps already provides 5v, why not use that… (for the prototype, for the time being, u get the pic)

Also missing are: the uln2803 driver ic; some resistors for led indicators; led indicators and front panel; and a duplicate headers sets for the audio signal jumping between the pcbs. (All of this was intended to be implemented, and is assumed to be on a to do list too.)

to do:    (updated 2/’12)
+ get driver ic
+ make embeded usb connected selector / controller, with win app interface over usb
+ manual selection from front panel
-add in led indicators
-make it ir / rf controlled
-make more pcbs
-put into nice enclosure
-put hold current limiting into relays (after they have picked up)
-use audio grade (not high current type) relays
-maybe redo for latched (without power to hold in position) relays. these relays are what i had plenty of on hand, and it’s what it was designed for.

as it sits being used on the computer. also tapped the power from the pc ps.

also, reused a cd-rom/dvd drive enclosure, to hold the pcb, so that it don’t fly all over, and short out on the pc.

Sometimes when the ideas hit you, it just keeps on rolling off, and working for you…

-CD-ROM / soundcard shielded cables
-the hardrive power connector, for tapping +5vdc in this case (upper left)
-audio jacks (from various sources: sound cards, stereos / portable radios, othere audio gear)
-standoffs (from embeded pc’s / dedicated controllers)
-some of the .1 headers (from pc’s and other sources)
-jumpers for temporary operation (from pc’s…)
-the power input cable (from another scrapped prototype project at previous job), with the female connector
-the black ‘jack panel’ (case scraps from another project)
-even the stickers that label the cables were scrap pieces when aligning new label, that’s usually just wated.

(you get the picture)

Basically, not reused (new) are:
-the pcb itself
-hot melt glue used to hold the jacks in the panel
-relays (they were disposed unused samples)
-some of the headers and the dip socket
-smaller components on the pcb (was too lazy to reuse, had new on hand)
-and the nuts holding the standoffs to the cdrom case, on the bottom.

used up scraps from casses that were leftover from a project at work.
also, hot glue works nice for temporary hold while building and a (semi)permanent support…

bottom view of the pcb.

yeah, it was a bitch to solder it all up. and then i realized that i forgot to wire up all of the audio signal grounds, so i had to do that after all of the wires were soldered to the posts. the ground bus is finished off in this pic.

a good use for those audio jacks and pc cd-rom/dvd drive audio cables that just get collected. used them for shielded audio signal wires.

another shot of the workbench, as it’s being used. it’s a beauty.
a work in progress, making the bench messier, and trying to find stuff.

the intended skeemehtick.
not much complexity to it, just needed something to help position components and route the wires… just like it’s ment to be used.
done in expresspcb. nice simple fast tool (and still haven’t learned eagle…). had a few pcbs done by those guys, not a bad deal.

(few more pics in the set, not included on here)

2/’12  update:

I finally got the controller portion built. It’s posted as it’s own project at


Checked off some of the items on the todo list.