[Lost81]

Hi guys,

I have a 120VA 9-0-9 dual secondary toroidal transformer I am using for my Mensa DIO. Since the AKSA 100W recommends the use of arc-quenchers to prolong the life of the switch, I was wondering if I need one for my DIO Power Supply as well. The DIO PS only uses a SPST switch for the Live wire.

I have a 100 ohm, 2W, flameproof resistor, and a 250V 0.22uF X2 capacitor for this purpose.

I am planning to wire have both components run in series between Live and Neutral after the switch. I plan to use a length of heatshrink over both components as insulation.

Is this correct?

Is this necessary?

Thanks.


-Lost81

[_scotty_]

Lost81,how many mfd of storage caps in the power supply do you have.
It is the combination of the large,300VA and up transformer and substantial amounts of capacitance in the supply which compound the problem. Your power amp has a much bigger power supply and looks like
dead short for a longer period time, this is what kills the switch over time.
I don't think I would even worry about it in this case. Even if you have to replace the switch in three or four years it probably only costs $5.The cap used in  an arc quenching circuit is usually a .022mfd 600 to 1000v ceramic cap no resistor is used.

[Lost81]

Hi Scotty,

I have no idea, but as it is a DIO (albeit modified), I am sure it is not significant. Maybe 7000uF max, divided between 2 capacitors, a couple of film and foil bypasses capacitors.

If it is unnecessary to add an arc quencher then it will be good too.
It will save me the hassle of hacking into the wiring for the mains.
Always a good thing: the less complexity and components, the less to go wrong.


-Lost81

[markC]

Hmmm...interesting subject. I'm in the process of building a pair of mono block amps; each sporting 8x 10,000 uf storage caps with a 750 va torroid. Do you believe some sort of protection is required for the switch? I'm using a 10 A spst rocker switch and must admit it looks a little light duty for it's task.

[_scotty_]

markC,you should use at least a 15 or 16 amp switch with a .022 600v to 1000v ceramic cap. When you power that amp up the lights should momentarily dim due to the inrush current. This will be kind of hard on the switch and even with the cap it will eventually die. The switches are inexpensive, buy a couple extra for replacements and don't make the switch impossible to get at, you will regret it when the time comes to do the swap.

[markC]

Thanks fopr the reply, Scotty, any idea on where to get? Digikey is where I found the 10A version; I didn't see any higher rated switches. It will be quite accesable, but the more durable and the longer lasting, the better.

[Lost81]

Get the mouser catalog.

Get those rocker switches which are HP rated.
Those are built to survive arcing from inductive loads (e.g. electrical motors).


-Lost81

[markC]

Thanks Lost, I'll check it out.