How do I...

Lo all,

I'm currently in the process of building a few amplifiers to power some 3-way actives.

I'll not bore with details on the amps themselves but I do have a question regarding the power switch.

I've bought some of those milled finish with inset LED push button types. I believe the brand is Bulgin.

Here's the switch:
http://uk.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=4303076&N=0

And datasheet:
http://www.farnell.com/datasheets/36350.pdf

OK, so basic stuff so far...

My question (finally) is how do I create a simple logic circuit that senses the closed circuit when the button is pressed and activates a relay to power on the amp? Likewise for turning the amp off.

If possible it would be nice to have a couple of seconds delayed startup of the amp modules to avoid turn on thumps and the reverse for turn off.

I'm a complete electronics idiot BTW. I've built 5 amps and various XO and other circuits but all were kits and simply required soldering - a monkey could be taught to do that. So any explanation will have to be very easy to understand otherwise I just get very confused very quickly

 

At least your amp will be vandal proof!

 

Yep, I won't even need to bend down to turn them on, I can just kick the switch without fear of breaking anything.

Alternatively, should I ever fall over and smash a screw driver into the gasket surrounding the switch and then accidentally try to wrench the switch out, it will remain perfectly intact.

They've thought of everything

 

Look familiar....

<<

These are low voltage, low current, momentary switches. You'll need some sort of logic detection and latching circuit to drive your relay.

 

i think avondale do some soft start circuits not sure about the logic stuff though.

 

There are such things as mains power-blocks with sequenced start-ups. Maybe that would be handy.

 

Forget logic and look at simple electro mechanical solutions.

All you require is a latching relay. Have you got two switches ?
or do you want to use only one to switch it on and off ?

Have you got a suitable DC supply for the led and switch ?
match the relay coil to the supply you are using.

Use the relay to start the amp via a soft start circuit, I am sure you can find a kit or pre built module on the web.

I tend to use www.rswww.com , but Farnell should have them

 

Hi Granville

Plan is to have a master switch on the rear and then this push buttom on the front for on and standby.

I've very recently come across this:

http://www.hypex.nl/docs/softstart.pdf

Which would seem to be OK for what I'm wanting. Is this assumption correct?

 

Looks like just the thing, and not expensive either

 

£35 + postage from the Netherlands + tax ain't expensive? hmm... I'd just use a normal switch and a slow blow fuse!

 

Well it does act as a softstart and also offers temperature sensing with associated safety measures. Plus you get the push button operation and will do bi-coloured LED if that sort of thing is appealing.

I guess ~£45 isn't too bad for that finishing touch, especially if you've already paid out good money for the enclosures, amp modules and power supplies.

Still hoping for something cheaper ie. £10-20 since I've got 6 of these to buy.

 

Are you going for the NCD?

 

Yep, sold the Chord last week - figured I'd never be able to scrounge up the other £8k to buy two more 1200E's.

This means I've got a nice wedge to devote to some DIY designs. I like the UcD700's for their clean and direct nature which allows music to be communicated clearly and honestly. Imaging was particular good, though they were a little cold sounding when compared directly to the AKSA 55N+. The NCD1 looks to be more of the same but with better measured performance.

I've been around most of the big reputation solidstate DIY amps and I'm comming to the conclusion that I've already had one of the best and sold it on without realising it. I wouldn't touch tubes because they just sound bloated, coloured and the bass is p1ss poor or at least the cheapish ones I've heard are like that.

 

Logic for momentary switch control of power

The picture below shows a unit available in the USA that I have used many times for just this application. It will switch 250V at 2A or you could use it to control a larger relay. It is made by Radio Design Labs www.rdlnet.com