Noob circuit design help

TechnoFreek

Hey guys, not sure if this the right place to ask this but hopefully it is!

I am a bit of an electronics noob but I can read basic schematics, am handy with a soldering iron and can follow instructions real well!

Can anyone design a basic circuit for me, tell me exactly what parts I need and how to wire it all up?

The basics of what I am trying to do is a speaker switch: two lots of speaker inputs from source A and B, a simple slider type switch to select between ysource A or B. there then is just one output, based on the switch position.

Once I have my head around that, I want to add a slight complexity to it - an output headphone socket. So: the switch will select source A or B which will output to either the output speaker terminals OR the headphone socket. If there is a headphone connected the output would be the headphones, otherwise the speakers.

I have drawn a simple diagram of what I am trying to achieve.

I do understand that such devices already exist however I have a couple of ideas like this that I am trying to develop into a single project box which has a number of switches, controls etc

Any advice here is greatly appreciated.

Michael Collins

Bascially all you need is the right switch and the right headphone jack. You need a double-pole, double throw (DPDT) switch, and a headphone jack that has two pass-through connections.

You can hardwire the two L- sources (A and to the L- output, and similarly the two R- sources can be hardwired to the R- output. And, provided the sources are completely separate, you can, and should, tie the R- and L- on the output together.

Now the tied connection should go to the headphone jack ground.

Now you're left with the 4 unconnected + terminals between the source A and B leads. This is where your DPDT switch comes in. You connect the two centre contacts of this switch to the L and R connections on the jack, one side of the switch goes to the source A L+ and R+ leads, and the other goes to the source B L+ and R+ leads.

Now finally, the jack should have another output (which is only connected when there's no plug in the jack), these connect to the L+ and R+ on the output.

Hopefully this is clear but I suspect it's not! Let me know which parts don't make sense and I'll try and make them clearer.

KK4SAM

Michael Collins wrote: »

Bascially all you need is the right switch and the right headphone jack. You need a double-pole, double throw (DPDT) switch, and a headphone jack that has two pass-through connections.

You can hardwire the two L- sources (A and to the L- output, and similarly the two R- sources can be hardwired to the R- output. And, provided the sources are completely separate, you can, and should, tie the R- and L- on the output together.

Now the tied connection should go to the headphone jack ground.

Now you're left with the 4 unconnected + terminals between the source A and B leads. This is where your DPDT switch comes in. You connect the two centre contacts of this switch to the L and R connections on the jack, one side of the switch goes to the source A L+ and R+ leads, and the other goes to the source B L+ and R+ leads.

Now finally, the jack should have another output (which is only connected when there's no plug in the jack), these connect to the L+ and R+ on the output.

Hopefully this is clear but I suspect it's not! Let me know which parts don't make sense and I'll try and make them clearer.

Please consider what power you are switching some power amplifiers do not like their output open circuit even momentory.In the day we had to use a wafer rotary switch wit Make before break contacts.Radionics/Farnell/Maplin all do them.The matrix needs a little bit of figuring out though.

FoxT

Michael Collins wrote: »

.....

You can hardwire the two L- sources (A and to the L- output, and similarly the two R- sources can be hardwired to the R- output. And, provided the sources are completely separate, you can, and should, tie the R- and L- on the output together.

I wonder if this would cause earth loop problems?

Assuming 1 or both amps are mains powered, if one is earthed & the other is not, or if neither is earthed, what will happen?

I expect that most modern amplifiers are protected against Open circuiting the outputs, but I cannot state that definitively.

It would help if more info. was available, ie
-How much power (how many watts) to be switched?
- Battery or mains powered amplifiers?

Also, what problem is the OP trying to solve here? It would be much simpler to have one amplifier with multiple switchable inputs. I am curious as to why you want to do this at all?


Regards,
FoxT