My switch is a 25A 250V Nikkai toggle switch. I think I'm good to go...

Took a few pictures of it because it's so pretty!

 

My project is in a wooden chasis, but I'll be using a bolt to connect up everything that needs ground via wires.

I hope you don't mean to secure the ground leads together using a bolt tightened against a wooden base. It might just about be OK to pinch the connections between some nuts on the bolt, but it is not good to rely on the tension of a bolt in wood for an electrical connection.

It would be better to use something intended for securing mains electrical connections, like a proper terminal block or junction box.

 

Black to Black and Red to Red is correct.

There is no way to know for sure what the secondary voltage is. It will be 6V or 12V, center tapped, but an educated guess would say 12V since we are told it is a 240 Volt transformer and the highest output voltage would be listed and can still be achieved with either 240V or 120V configuration on the primary.

Danny

 

I hope you don't mean to secure the ground leads together using a bolt tightened against a wooden base. It might just about be OK to pinch the connections between some nuts on the bolt, but it is not good to rely on the tension of a bolt in wood for an electrical connection.

It would be better to use something intended for securing mains electrical connections, like a proper terminal block or junction box.

I shouldn't have said bolt, because I'm not actually using one. I'm using one of those Radio Shack solderable terminal strips and I soldered all of the connections together with a piece of 12 gauge wire.

http://www.radioshack.com/product/index.jsp?productId=2103233

that except the 5 connections are soldered together.

That's what I am doing.

Thank for the concern.

 

Black to Black and Red to Red is correct.

There is no way to know for sure what the secondary voltage is. It will be 6V or 12V, center tapped, but an educated guess would say 12V since we are told it is a 240 Volt transformer and the highest output voltage would be listed and can still be achieved with either 240V or 120V configuration on the primary.

Danny

Does "12V" mean +/- 12V or +/-6V?

 

Hey guys. I bought the transformer on eBay, but I couldn't find it before when I made the thread. I just found the new listing they must have put up.

http://cgi.ebay.com/12V-Transformer...976?pt=LH_DefaultDomain_0&hash=item1c1c6f3740


So according to this, it's a 120V transformer with +/- 6V (which makes 12V). But that doesn't change how I'm going to wire it, right?

 

The E-bay advertisement says:

New Surplus Chassis Mount Transformer Okura LP-427

6V-0-6V CT 1A

Input: 110/220VAC 60Hz
Outputs: 12VAC @ 1A (6V-0V-6V)

However, the diagram shows two 120v windings for the primary, so it's 120v/240v.

No changes will be necessary.

One of my favorite suppliers, MPJA, carries that same transformer for $3.95:
http://www.mpja.com/viewallpict.asp?dept=45

 

Cool thanks for the link. I've been buying surplus lately, so I'll definitley look at that site.

 

Thanks everyone - for telling me I'm forgiven.

For those new posters; be aware. Do something right and no one remembers. Do something wrong and no one forgets.

 

Thanks everyone - for telling me I'm forgiven.

For those new posters; be aware. Do something right and no one remembers. Do something wrong and no one forgets.

Beware....this will come back thousand fold.

 

So it's alright to use the fuses after the DPST switch? In that case, that simplifies things a lot. Well of course I can. I'm acting a fool right now, so excuse me.

I think I'd like to use two fuses, for some reason. I have a crapload of nice panel mount fuse holders, so I think I'll do two.

Thank you for clarifying the fuse value, because I really never knew how to do that correctly. I'll go with a 5A fuse on the power amp, and I guess 1A for the other transformer.

Thanks.

NO!

I would use one fuse and one SPST switch.

The fuse is the first thing that gets connected to the AC mains.
The BLACK LIVE wire from the AC power cord goes to the tip of the panel mount fuse holder. I would put heat shrink tubing where the LIVE is connected on the fuse. In your case a 1A-SB fuse should do. I can't see you taking more than 100W from this thing.

The other terminal of the fuse is connect to the SPST POWER switch.

Connect the black leads of the two transformers to the other terminal of the switch.

 

Most people trust this guy....He says DPST switch and then fuse. Not trying to say you are wrong, but this is the way I've seen it done many times.

http://sound.westhost.com/psu-wiring.htm

 

I agree.fuse should come first, even though they tend to go after something blows or is melted.

 

I agree.fuse should come first, even though they tend to go after something blows or is melted.

Okay then. But can I still use a DPST switch because I already have one and it cost me over $10?

 

Okay then. But can I still use a DPST switch because I already have one and it cost me over $10?

Well clearly you can: even if you only want the SPST function, no-one is forcing you to use both poles. It's quite common to switch both live and neutral though.

The real no-no is to put a fuse in the neutral, as that can easily leave the equipment "hot" in the case of a fault. So one fuse, in the live connection.

 

Well clearly you can: even if you only want the SPST function, no-one is forcing you to use both poles. It's quite common to switch both live and neutral though.

The real no-no is to put a fuse in the neutral, as that can easily leave the equipment "hot" in the case of a fault. So one fuse, in the live connection.

Oh sorry did you think I mean't TWO fuses. One on live and one on neutral?

I meant TWO, but ONE per each transformer's live line.

Is that possible? Or should I just group the load together into one fuse?

 

That Rod Elliot guy is a wizard in Land of Oz. I don't know if they have different standards down under or what. You'd be best to check CSA/UL standards for North America.

The fuse is to prevent a disastrous fire. If the DPST switch comes first and it shorts you would have a lot of current (15A) flowing before the house circuit breaker trips.

Sure you can use the DPST switch but put the fuse on the LIVE side first. NEVER fuse the NEUTRAL side.

I would go with one fuse first at the LIVE line.

 

That Rod Elliot guy is a wizard in Aussieland. I don't know if they have different standards down under or what. You'd be best to check CSA/UL standards for North America.

The fuse is to prevent a disastrous fire. If the DPST switch comes first and it shorts you would have a lot of current (15A) flowing before the house circuit breaker trips.

Sure you can use the DPST switch but put the fuse on the LIVE side first. NEVER fuse the NEUTRAL side.

I would go with one fuse first at the LIVE line.

In that case, I'll go with one fuse one DPST. I calculated around 5A for the one transformer and 1A for the other, so I'll go for somewhere around a 6A slow blow.

Thanks.

 

Remember, 6A x 120V is 720W. Are you going to draw that much power from this baby?

 

Depends on how BIG the baby is.