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Old 3rd December 2003, 11:24 AM   #1
Wright is offline Wright  United States
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Cool Show me your cool switches!

Hello Gang,

I am starting the design process for my new amp and I am looking for a nice power switch to use. I had my heart set on using one of those pictured in this thread, but I have spoken with Hugh Dean of Aksa fame and he says I need a switch with a 10A/120VAC rating, whereas those switches are 50mA/24v
I'm sure you guys have run across some neat switches that qualify so I'm hoping you can give me some recommendations, with or without leds. Thanks!

George
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Old 3rd December 2003, 11:32 AM   #2
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You can use any switch you like with a suitable relay to switch the load.
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Old 3rd December 2003, 11:55 AM   #3
Wright is offline Wright  United States
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Now we're talking! I must confess though, since I am an electronics novice, I'm not familiar with the relay concept. I tried a search on google and got many hits but no explanations. Does it simply tie it to another switch with a more appropriate rating? I would appreciate if someone could explain the concept to me. Thanks,

George
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Old 3rd December 2003, 12:09 PM   #4
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Yes, the switch just supplies enough current to energise an electro-magnet within the relay which then pulls a pair of contacts together to switch the much larger current.

If you use a relay you will also require a permanent supply to energise the relay when the amp is "off" but a tiny transformer mounted on the same board as the relay and permantly connected to the mains will suffice.
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Old 3rd December 2003, 12:56 PM   #5
Wright is offline Wright  United States
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Thanks Richard,

I have done some more searching and I came up with a couple threads talking about power relays. It looks like I can use one of the lighted switches I wanted to without a seperate transformer, if I pick this up:

"...I ended up buying a Potter & Brumfield (of Tyco Electronics) bistable impulse relay:
Spec sheet:
http://www.pandbrelays.com/datashee...ys/S8990_DS.pdf
You can figure out what part number you need at the bottom of the first page of the spec sheet. I ended up going with the 120VAC operated version (for use in the USA) with 20A contacts bought for about $35 from here:
http://www.mouser.com//index.cfm?ha...roductid=341943
The design of the relay assembly is pretty straightforward and is amusing to watch for the first few operations.
For my momentary push button, I used a Vandal switch from Bulgin (www.bulgin.co.uk), the MP0031 for my 1/4" (6.35mm) front panel, purchased for ~$14 from www.newark.com. I picked up the Vandal switch hint from a thread where an Aleph used one obtained from Conrad."



So it seems this will work. I do need to figure out precisely how to implement it but I suppose this will have to wait until I get my amp schematic as I have no knowledge of basic circuits. I am a bit curious...will such a relay degrade the sonics of the amp at all?

Also, I'd still love to see pictures of your favorite switches, my mind isn't quite made up just yet

George
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Old 3rd December 2003, 09:19 PM   #6
lgreen is offline lgreen  United States
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Default switches

As the author of the thread you cite, I've got more experience looking at switches than I ever wanted to have. Here are my thoughts to you.

1. this link has a ton of switches if you want to spend hours checking them out.

http://www.newark.com/products/browse/1_4_13_0.html

Note switch sizes. Realize that 22mm switches are almost an inch wide, so do you really want something this big?

2. NKK switches are my favorite. They will send you a few free samples, and these are very nice switches. Get on their website and fill up a sample bin, put yourself in as a consultant. I got a few free, along with a catalog (a very big catalog), but my 2nd order was rejected and a sales rep called instead. So my advice is to be careful and get what you want on the 1st order. Check out prices, some of these are very expensive and most places don't stock the switch configuration you want.

http://www.nkkswitches.com/Default.asp

click on product line.

3. Other swithmakers that have a good selection are Omron, E-switch and EAO. E-switch.com has free samples but i've not tried to get any.

4. If you are going to switch a relay, don't forget to put in a diode. Then again, maybe you don't need one for a high power relay. That's why you need to read up on this by looking at some application notes that deal with using relays.

One good app note I used for small signal relays is the NEC/Tokin app note that I got here:
http://www.nec-tokin.net/now/english...on_notes_e.pdf

but it looks like its down, email me and I'll send the pdf to you.

5. Have fun, hopefully it wont take you long to find the ideal switch.
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Old 3rd December 2003, 10:17 PM   #7
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Quote:
http://www.nec-tokin.net/now/english/product/pdf_dl/relay_function_notes_e.pdf
Doesn't work
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Best regards: Holger
www.holgerbarske.com - Deutschsprachiges Paradise-Support-Forum
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Old 4th December 2003, 10:25 AM   #8
Wright is offline Wright  United States
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hey lgreen,

Thanks for your input, NKK switches looks like a great resource. I think I am going to try a relay so I have sent you an email about the pdf. Regards,

George
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Old 6th December 2003, 07:30 PM   #9
Possum is offline Possum  United States
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Wright,

The setup you quoted (I believe that was from my post) was what I used for my AKSA amp. I don't think you can use one of the Bulgin illuminated switches as a direct replacement for the one I used.

On Bulgin's website, the illuminated switches only have contact ratings of 50 mA, 24 VDC. The MP0031 switch I chose had 5A, 250 VAC contacts. If using the switch and relay the same way as me, you'd have about 120 VAC passing through the switch for the impulse required to trigger the relay's solenoid.
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Old 6th December 2003, 08:11 PM   #10
sam9 is offline sam9  United States
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When an ampilifier reaches a certain power level you need to start thinking about soft start, in-rush limiting, triacs and so on. Keeping that in mind while I've disassembled a couple of commercially bult amp , etc salvage enclosures and transformers) I've noticed that frequently the "on" switch never passed the main current. Instead it activates a relay, a triac or some other device that switches the main current.

This adds complexity, but would allow more free reign in the aesthetics of selecting a swith. If you start building really big amps you have to do this anyway. If you want a "cool" switch, that's probably something to investigate.
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