Help with design of 3.5mm jack switch box

Borden

Borden

Borden

Soldato
Joined
14 Jul 2005
Posts
3,810
Location
Surrey
Hi guys,

As the title suggests, I want to build my own 3.5mm jack switch box. I couldn't find any pre built ones and so i may as well do it myself.

The purpose of it will be to let me choose whether my speakers or headphones are connected to my pc at any one time.

My question is to do with the switch. From what i've gathered it looks like i will need a DPDT toggle switch to switch the L/R channels simultaneously. See below diagram:

switchbox.png

Now what i'm not sure about is what to do with the ground connection. Is it even needed? Using the DPDT switch there's no way i can include the ground wire in the switching mechanism. So what do i do with it? If it makes any difference, i plan on connecting my headphones (Beyer DT770) to a Project Headbox Mk2 which will be connected to the switch box. Will the amp require the ground connection?

Looking at RCA - Mini jack interconnects, it doesn't seem that there's a ground cable at all, or have i got this mixed up? If i don't need it then it will make my job much easier.

Help me OcUK!
 
Can't see anything wrong with that, you can get proper signal selector switches that allow you to use more than 2 inputs which is what I would use if you're going to all the hassle of DIY. :)
 
Thanks for your input.

Do you have any links to those switches? Just having a look through the switches at RS and can't seem to see any that fit your description. Any specific models i should be looking at?

Cheers.
 
I wish I could remember the name, I just searched ebay and come up with nothing. :(

It's like a volume pot, but instead of being smooth when turned, it's clicky, and each time it clicks it switches....

EDIT: Look at ebay item number 290314112419

They're called rotary switches... :)
 
I have used a 4 pole 3 throw switch in my pre-amp and in a little switcher box I made for my dad. Got it from a high street electronics store for about a quid. Works well, and was easy to make once I got my head round how to wire it up.

Edit: Sorry should have said it was a rotary switch.
 
Last edited:
Lorlin make some fairly cheap and good selector switches. Got x2 myself for a x2 in / x2 out switchbox, but just haven't got around to building it yet.

When it is built I will have to post a project log on here.
 
So i've been looking at some rotary switches, particularly the Lorlin ones -Ad- mentioned, and i think i could make do with a 4 pole 3 way switch and only connect three poles. The third, or centre, throw could be used as an intermediary 'neither' position so neither the headphones or speakers are conencted.

Am i right in thinking the switches won't do a full rotation, but rather only click depending on the number of throws it has? eg. If it has 3 throws then you can turn it 3 clicks in one direction before having to turn it back the other way.

Cheers for your help guys, i'm new to this kind of thing so your advice is much appreciated. :)
 
Does this thing do what you need?

Konig Speaker Headphone Switch

(google it, first result) under £7 delivered.

HTH
:)
 
That looks like the sort of thing. It doesn't look very attractive though :p Cheers for the suggestion.

I think i'm going to just build it myself as i like building stuff like that and can personalise it more.


Also, does anyone have an answer to this:
mark1 said:
Am i right in thinking the switches won't do a full rotation, but rather only click depending on the number of throws it has? eg. If it has 3 throws then you can turn it 2 clicks in one direction (3 positions overall) before having to turn it back the other way.
Click to expand...
 
Just thought i'd update this if anyone's interested. In the end i went with a Lorlin rotary switch like -Ad- suggested. Took a while to get everything delivered as i changed my mind about using ordinary equipment wire and bought some Starquad instead.

The first enclosure i bought also turned out to be way too small, the switch would not fit at all. Serves me right for not checking beforehand. The second enclosure i got is much more appropriate i feel. It fits much better on my desk.

I'm now thinking of adding a couple of small LED's to indicate which one is connected. Still undecided as it may ruin the minimal looks, it would be easy to fit though.

Anyway, here are some pictures:

All the parts
DSC00170resize-1.jpg


Internals
DSC00171resize-1.jpg


On my desk
DSC00172resize-1.jpg



Cheers once again for all your advice guys. It might seem like a simple project, but for a newbie DIY'er like me it's good experience!
 
Good job, looks nice and clean.

I have exactly the same jacks, knob and rotary switch in various projects. :p
 
Last edited:
p4radox said:
Good job, looks nice and clean.

I have exactly the same jacks, knob and rotary switch in various projects. :p
Click to expand...
As it happens, the first enclosure i bought that was too small was the same size as the one you used for your cmoy. That might give you an idea of how optimistic i was being :D

I used different jacks when i built my cmoy (these) but much prefer the ones i used for the switchbox. Bigger solder tags and higher quality feel.

MikeHunt79 said:
Nice work, what enclosure is that?
Click to expand...

Thanks. It's a Hammond 1455K1201. You can get it at Farnell, Rapid etc. I used a Hammond enclosure before and was impressed by the quality, so i got another!
 
Nice one, looks awesome.

Was actually in ******s in Kingston earlier today looking at some lorlin rotaries. Was trying to figure out what I needed to make a swtichbox similar to yours (2 in 1 out) but for analogue 5.1 audio (R, L, Sub, RS, LS). Then I realised that the lunchtime beers had scewed my mind and it would be silly to try to make one of them.
 
You must log in or register to reply here.
Back
Top Bottom