Can the Hairball 1176 push buttons handle 240 volts for power switch?

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canidoit

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Apr 6, 2009
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It sais on Hairballs little push button 1176 manual to check the specs if it can handle it, but his push button switches did not come with spec sheets. His manual sais to use Neutral from the IEC to wire it to the 1176 push buttons if voltage is an issue. Is this safe to do, that's 240 volts going thru those push buttons that are directly in contact with the user pretty much and sparks could fly?

Would this cause any form of issues having the power direct from the IEC going thru the Push Buttons, like grounding, noise, magnetic field, whatever?

How about adding a snubber, I read this up on Drips La2a manual? Is this possible with the 1176?
 
andrew_k said:
luis said:
you can connect the neutral to the switch.

Please don't switch neutral and leave hot connected.  :eek:

It's not the best scenario but i have seen commercial gear that switches only the neutral.  In this case you would want to fuse the hot.

Here is a previous discussion on this topic:
http://www.groupdiy.com/index.php?topic=30732.msg372447#msg372447

Thanks,

Mike
 
JoleFIN said:
Or, a better version would be to connect the secondary side on the switch and save your finger tips of possible burn-outs.  ;)
Yeah but wouldn't that mean, that the power transformers will always be on if there is power going thru the power leads and all you are doing is shutting on/off power after the power transformer that goes to the board?

How does Universal and Urei do it? Are these push buttons have lower voltage rating than the ones on Urei and Universal audio?
 
canidoit said:
How does Universal and Urei do it? Are these push buttons have lower voltage rating than the ones on Urei and Universal audio?

UA uses a meter bank with a higher rated switch in the on/off position.

The companies that offer these have very large min orders, I hope to be able to offer these in the future.

Mike
 
urei used the same type of switch that mike sells now for many years, so did purple.  UA does have a higher rated power switch, but i've never seen one of the old switches fail.

and yes, if you switch the secondary of the transformer, then the winding resistance in the power transformer will be dissipating power as long as the unit is plugged in. 

ed
 
Just to be shure, how are you guys wiring your iec to the switch on mike pushbuttons? Am I doing wrong on having the switch connected to neutral, and to primary?


by the way the iec connector that i´m using already has a fuse.
thank you all,
 
If you're switching both the hot and neutral with the switch that is a little too much current for the terminals to handle.

You're better off switching one and wiring in parallel (using two terminals).  This will double your current handling and get you in spec.

Do you have the wiring guide?

Mike  
 
I have your guide for the pushbuttons is that the guide you are refering to?

According to your guide. I connected the "From IEC" with the Neutral cable from the IEC connector, and the "to primary" to the primary wire in the transformer. This way I don´t have the neutral and Hot switched, Right?? ???


Sorry to be such a bore, buy my lack of knowledge and my bad English sometimes just play some tricks..! But I just thought I had the switch correctly wired.

Thanks once again Mike.
 
Have a look at Skylar's guide:
http://www.filefactory.com/file/ag514d3/n/SG-1176-RevD-Wiring_ALLv3_pdf

Here he is switching the "hot".  Imagine the "A" and "B" on the meter board in his diagram or the polls on the switch in my diagram.

If you want to switch the "neutral" then do the same thing except run that wire through the switch.

Mike
 
if you have a question that can be answered by the schematic
you can always look at the schematic , but
good discussion especially in this energy conservation time
 
Seems to me the problem is current more than voltage. Whether you switch the neutral or hot, the current is the same. If you switch the secondary, the current is actually much higher.  Since the switch is DPDT, it is a simple matter to parallel both sections of the switch and double the current carrying capabilities.  In a 240 volt unit, the current will actually be half what it is in a 120 volt unit.  The dielectric rating of that switch under normal conditions (50 - 100 degrees Farenheit, < 80% humidity) should be more than sufficient to switch 240 volts safely.  I've built many 1176's using those switches with the switch sections paralleled and never had a failure. Until I wrote this post anyway, I guess we'll see :)

---Joe
 
I'm no expert for sure...but this is how I read it.

The current handling capability of the switch terminals is 500ma.  So in parallel you've got 1A.  On a 120V system your 1176 is drawing say 200ma and as much as 800ma with toroidal inrush.  On a 240V system these numbers are halved.  So you are within spec in both instances.

As it was explained to me, the main difference between a switch rated for 120V and 240V is the terminal spacing.  At the hot lead at 240V there is a chance (at any current) of arching.  Switching the neutral (if your region has one) will reduce this risk (near 0V here).  Keep in mind you're only switching what you think is the neutral, who know what is going on in your wall, especially if you're in PRR's kitchen ;)

That said it's been well documented that these switches have been used for years by other 1176 manufactures as on/off switches.

Mike
 
Nah, regardless of where you switch it, the voltage potential (and current) being switched is the same.  Take a voltmeter and measure it yourself if you don't believe me.  The electrons don't know and don't care which is "hot" and which is "neutral", all they care about is the potential difference between the two terminals.

Switching the hot lead is much safer IMHO, because there is far less chance of finding a current path back to ground if the hot is switched out of the circuit. If the unit is mounted in a rack, chances are the chassis is at ground (neutral) potential anyway.

---Joe

Echo North said:
At the hot lead at 240V there is a chance (at any current) of arching.  Switching the neutral (if your region has one) will reduce this risk (near 0V here).  

Mike
 
joe-electro said:
Switching the hot lead is much safer IMHO, because there is far less chance of finding a current path back to ground if the hot is switched out of the circuit.

Definitely agreed.
 
JoleFIN said:
Or, a better version would be to connect the secondary side on the switch and save your finger tips of possible burn-outs.  ;)

It is a bad idea to leave a transformer connected to the mains with no load.  It's a bit like putting your car in neutral & putting your foot hard on the accelerator for a few hours, revving the nuts off it.  You're generating lots of power but it's not being dissipated properly.  The engine gets thrashed & would eventually explode.  For the same reason wall warts shouldn't be left plugged in if they are not powering anything

Also say the transformer was 240v:24v    (I know there are 2 x 24v in this case)   Then the switch would be handling roughly 10 times the current at the 24v than it would be at 240v for the same load.

I swapped out this switch for a toneluck one from Rapid, which seems to spec better (on paper at least).  I wired up with the live using to poles.   If you were really worried you could use a 4 pole switch, so the current was dissipated over 4 instead of 2 contacts.
 
It just occurred to me, arcing can be minimized by putting a 0.047 - 0.1 uF 600V capacitor across the switch contacts.  It helps equalize the inductive reactance from the transformer.

---Joe
 

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