Ok that's cool. I might only need a 4 position as I brought an iec socket and it has a fuse and dpdt switch. I could use that as everything off and then the rotary switch to choose what output I will use. Correct?

 

Well, um, not really. You can't use that to shut off the battery because the battery is not fed through that plug.

 

It's kind of an external switch it's not wired up inside. It's one you can wire up afterwards. So I could have live connected to one side of switch and battery connected to the other
Or do I need the neutral wired up to the switch as well as live? Hope you understand what I mean

 

I'm not sure of what you're describing. One thing for certain, you don't wire up the hot AND the neutral to the same switch. One little mistake and you can blow the switch. Also, I wouldn't suggest using the same switch for 230 and 12 volts (AC / DC respectively). Too much chance to hit the battery with high voltage. Sudden and loud explosions have been known to occur.

Take my drawing and add in one more switch node (the blue box). Instead of using 12 volts use the main power (230 VAC) and use that to control a 24 volt relay. The contacts will be isolated from the main power and all potential accidental cross voltage danger is removed.

Please don't ask me to redraw the circuit; by now you should know how to handle that on your own. If you're not certain, post your own drawing - or copy and modify the one I gave you. If we see any potential dangers we'll alert you before you commit anything to hard wire.

Good night. Grass is cut, garbage is at the curb, it's time for bed.

 

Ah no its not what I was meaning.
Like this.
But if it's not safe then I will not do it like this

 

OK, here's my final input to this project. If you wish to do something different, I wish you good luck and much success. There's a certain measure of pride in making it your own.

With this you can stay with the 2P5T. If you can't find a 2P5T you can use a 3 pole or 4 pole - however many poles you wish, and just leave them totally unused. You NEED at least 2 poles. I recommend 5 throws because in one position you have an "OFF". You CAN use 4 throws if you wish. But then you need a way to shut everything off. HOWEVER you wish to do that - it's up to you. You're the engineer now.

Good luck.

 

Sorry Tony, that's not going to work. There will never be enough current through the 100k resistor (about 2mA) to operate the relay.
Maybe connect the poles of the switch to live, with resistors in each triac gate to limit the current. Then use a 240V AC relay - connected between switch and neutral - to switch the battery.

 

Yeah, I was a bit concerned about the low current. The reason for the low current is because the rotary switches are typically not built to handle more than a half an amp. Also, most (that I've seen) won't even handle more than 115 VAC. 230 is definitely not advised. It's a catch 22.

I chose those resistor values because they limit wattage to 480 mW. That also means there's a need for half watt resistors. If we drop the Rt by a factor of 10 we up the wattage and the circuit would need 5 watt resistors. I was trying to avoid the excess heat. That's also why I opted to use a separate switch to control the 12 VDC.

At this point I'm at the limits of my abilities. I think I need to step back and allow someone else the opportunity to improve on this design.

I'm also concerned that the resistance of the coil will change the current through the circuit and possibly over heat the resistors. Off hand, what's the current requirements for a BJT? Maybe a transistor can switch a 12 volt relay. Honestly, I'm stretching for an answer now - so it's probably best I sit silent and learn something.

 

A sensitive gate triac may need say 10mA. But it needs that at the start of the cycle so the current will be much greater at the peak voltage needing bigger resistors...
I think it makes more sense to use relays - a PCB mount 230V coil relay capable of switching 4A needs just 7mA.
The black and white rotary switches (the ones with the adjustable stop) are rated 250V AC and 150mA.
So that gives: (ignore the component type numbers - they're just some that Eagle knows about!)

 

Thank you both, I found a rotary to suit
http://www.jaycar.co.nz/Electromech...ches/Rotary/2-Pole-Sealed-PCB-Rotary/p/SR1212

I have one last question, if there is no 230vac, can I still switch it to battery. Or does the relay have to have power to switch the battery on. Probably a stupid question but I have to ask

 

Yep that's the switch I meant.
Good luck (and be careful with mains wiring).

 

Sorry I updated post. I lied I had another question .sorry Albert

 

I have one last question, if there is no 230vac, can I still switch it to battery. Or does the relay have to have power to switch the battery on. Probably a stupid question but I have to ask

Good point - no you can't.
Will there always be a battery? If so you could use 12V relays and the same switching fed from the battery.
Difficult question, this one.

 

Thanks!
Can I get a rotary switch that has a 3 with same input and one with different do you know what I mean?

There is a popular range of rotary switches that have a lock washer under the bottom spindle nut - it has a spigot that you locate on one of the holes to select how many positions the switch has. The switch has 12 position tags, but the rotor can have wiper contacts for 1, 3 or 4 poles.

The name elgin is at the back of my mind, but I'm not sure - maybe someone else can fill in the correct make.

 

Yeah there is always going to be a battery. Bugger just when we think we've got it.
Yeah might have to do that. Just hope battery doesn't die and not being able to charge it haha

 

I think there is a simpler way to get everything to work.
Would you ever want the amp to run from the battery even though the mains was connected?

 

Na only use battery when disconnected from mains

 

Na only use battery when disconnected from mains

Aha! Await circuit tomorrow...

 

Awesome thanks Albert!

 

Here it is - but it still has a problem! S1 switches mains power to the charger and it is assumed that the output of the charger can be permanently connected to the battery. S2 switches on power to the amp, from the mains if available, otherwise from the battery. The problem (maybe) is that S2 has one pole connected to the mains and one pole connected to the battery and I'm not sure about the safety of that. When these switches are used as dual pole mains switches you have live on one pole and neutral on the other, but...

To get around that needs an isolated power source fed from the mains - e.g. a small mains transformer, or small switch-mode supply.

What do others think about the safety of having mains and 12V on the same switch?