Is there a better way to wire this?

Tonyr1084

Joined Sep 24, 2015
7,853
Ah right ofcouse it's like a bridged rectifer right? What if I changed the switch to the dc side of the circuit instead of the ac side would that work?
By changing to the output - or "DC side" you can control the power going to the amp. However, the PSU is ALWAYS on and so is the Charger. And no, it's not like a bridge rectifier.

Controlling their output is not the way to handle this unless you want to have a master switch that can turn both the PSU and the Charger on at the same time. THEN you have control over the circuit. All you're doing is selecting the DC source for your amplifier.

There are so many different ways you can control this but it's not the way I'd go with this if it were my project. I still think I'd go with the rotary switch, transistors and relays (and a couple flyback diodes).
 
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Thread Starter

camg

Joined Jun 3, 2016
25
Nice I will do that then :)
So would that mean I would have a voltage Drop across the diodes right?
I was wondering about this as it might affect the charging of the battery?


Sorry it's just the way I find it easier to explain

I have a 12v sla battery
A 230v to 12vdc psu
And 230v charger for the 12v sla.

State one: everything off
State two: only battery on
State three: only charger on
State four: only psu on
State five: only psu and charger on

Any order doesn't matter.
Thanks
 

Thread Starter

camg

Joined Jun 3, 2016
25
Ah didn't see you had posted on the next page.
Yes I see what you mean.
That's what I was thinking, they would still have power going through them if the where working or not.

Il go with your idea.
Might take a bit of studying to figure out how to do that but yeah haha.

Thanks
 

AlbertHall

Joined Jun 4, 2014
12,345
This might do the job. You wouldn't need anything other than the switch - but I don't know whether it would be OK switching mains voltage. You could ask the supplier for voltage ratings.

Anybody else care to comment?
 

Tonyr1084

Joined Sep 24, 2015
7,853
This might do the job. You wouldn't need anything other than the switch - but I don't know whether it would be OK switching mains voltage. You could ask the supplier for voltage ratings.

Anybody else care to comment?
Please read ALL posts. it's already been covered that the rotary switches certainly won't handle the 230 volts. In the case of the first switch I offered as a solution - it's BEST current rating was 500 mA (half an amp) In NO WAY could that handle the job.

And it looks like you forgot to post what it is you refer to when you say "This might do the job". What is the "This" you're referring to?
 

AlbertHall

Joined Jun 4, 2014
12,345
Please read ALL posts. it's already been covered that the rotary switches certainly won't handle the 230 volts. In the case of the first switch I offered as a solution - it's BEST current rating was 500 mA (half an amp) In NO WAY could that handle the job.

And it looks like you forgot to post what it is you refer to when you say "This might do the job". What is the "This" you're referring to?
Oops: http://www.ebay.co.uk/itm/New-4-pol...f245318&pid=100033&rk=8&rkt=8&sd=121678298243

I have read all posts but clearly glossed over the blanket ban on rotary switches.
 

Thread Starter

camg

Joined Jun 3, 2016
25
Hey Tony if you have time would you please draw a quick diagram on what you mean? I learn a bit faster when I have a picture to refer to. No worries if you don't have time.
 

Tonyr1084

Joined Sep 24, 2015
7,853
I don't know why I do this! Maybe it's the challenge. And given my "Old World" knowledge (limited at that) of electronics - I'm sure there are better solutions. However, most people here don't feel like being your personal engineer to design circuits. I only do it to see if I still can come up with something. Still, there ARE better ways. In fact, I don't even think it's worth trying to power an amplifier from three different sources. I'd say pick one and enjoy.

So here's my solution for now:

OK, S1 is your main switch. It's needed to shut things down. Without it, once powered everything will stay on, so you need S1 to shut everything down. S1 is a DPDT switch. S2, S3 & S4 are momentary switches and are only needed to activate the Triacs and/or the SCR. If I were to go at this it'd probably be something more elegant, but for now, with your level of understanding I don't want to get you in over your head and leave you frustrated.

Once the Triacs and the SCR are switched on they stay on. Hence, the need for S1. When they lose power they shut off.

Now, honestly, this is about as far as I'm going with this. You've gotten several good answers. Time to start experimenting with things. One word of caution - BE DAMNED CAREFUL WITH THE 230 VAC. Can give you a nasty shock and burn. Could even kill you.

Good luck.
 
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AlbertHall

Joined Jun 4, 2014
12,345
There is a problem with the triacs in this diagram. R1 needs to be connected to the other main terminal of the triac in order to trigger it. Second, the triacs will not stay switched on. They will switch off at the end of the mains cycle, so the momentary switches need to be latching - normal SPST switches.

[EDIT] No. The R1 connection is OK but the triacs need to be the other way round. MT1 to the load and MT2 to the mains power.
 

Thread Starter

camg

Joined Jun 3, 2016
25
Wow thank you so much for your time!
I really do appreciate it Tony.
You have really gone out your way to help
That's awesome.

Can't wait to put it together
 

Tonyr1084

Joined Sep 24, 2015
7,853
the triacs will not stay switched on. They will switch off at the end of the mains cycle, so the momentary switches need to be latching - normal SPST switches.
Honestly I wondered about that. I haven't used a triac since high school. Perhaps the rotary switch can work in this instance since the control lines are only drawing about 25 mA. A rotary switch can easily handle the current. Also good catch about the control line.

I'll redraw it since I got a few hours before I can go outside and cut the grass. (today is grass cutting day)
 

Tonyr1084

Joined Sep 24, 2015
7,853
IN POST #28: I've removed the drawing because of errors and I don't want you mistakenly building the wrong thing.

The new drawing goes back to using a rotary switch, and gets rid of the SCR because it's not needed.

Here's the breakdown: S1 is a 2P5T rotary switch. Most of them are not rated to handle 230 volts so I've used R1 & R2 to form a voltage divider to drop the voltage down to around 21 volts at around 2 mA, so the switch can handle that with no problem. The battery is not going to be on the rotary switch because, again, the switch can't handle more than 250 mA. Using the SCR would make that possible but with an SCR, once triggered you have to remove power in order to get it to unlatch. For that you would have needed a switch. Since a switch is needed either way I just opted to cut down on the component count and go with a battery switch (S2) and be done with it.

In the circuit, S1a in position 1 - the PSU and the Charger are both off. Position 2 turns on just the PSU. Position 3 turns on both the PSU and the Charger. Position 4 turns on only the charger, and in position 5 again, everything is off. So you have an "OFF" at either end of the dial. Originally it was going to be for the battery circuit but I've gotten rid of that. I guess that means you can get away with a 2P4T switch now. Just ignore my position 5 on the drawing. It all depends on what's available to you.

On the 230 VAC line, you need to connect the two resistors to the neutral line otherwise you won't have a voltage divider and you could arc your switch (S1). The neutral line (the arrow) goes to all other 230 devices. I neglected to show the negative line of the battery (12 VDC). Some things are "Understood" to be there.

I chose R1 & R2 values to reduce the voltage and amperage. At these values you are producing 0.48 watts, hence the need for 1/2 watt resistors. If you want to use 1/8 watt resistors you'll need to substitute the values for R1 (1MΩ) and R2 (100KΩ) which would give you 0.048 watts. 1/8 watt = 125 mW (0.125 watts).

Again, please be careful with that 230 VAC. We'd hate to lose you.

Good luck. And thanks again to Albert Hall for pointing out my errors. I really need to get a good sim program.
 

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Thread Starter

camg

Joined Jun 3, 2016
25
Grass cutting day haha :).
Cool I see how it all works.
I studied triacs and scrs last night.
I understand the basics of how they work now. I'm learning alot reading everyone's posts. Thanks again for helping me Tony. :)
I will be careful too.
 

AlbertHall

Joined Jun 4, 2014
12,345
It might be better to use that 5th position to control a MOSFET to switch the battery. At the moment, both the battery and power supply could be powering the amp at the same time. I suspect that is very undesirable.
 

Thread Starter

camg

Joined Jun 3, 2016
25
Yeah that would be good if I could do that Albert, because if anyone else uses the speaker box they will not know to turn off battery or psu first. Or me if I forget or have had a bit to drink haha. The amp may be able to handle it though it's rated 8- 26vdc it's a tpa3116 sanwu blue. Nice we amp really.
 

Tonyr1084

Joined Sep 24, 2015
7,853
3P5T. Using a 3P4T would mean something will always be on. Having a 5 position switch means one of those can be "Everything off".
 
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