PDA

View Full Version : Stiffening capacitors in a wall outlet



Raven
11-04-2005, 04:45 PM
Just a random thought, but if I were to wire two ~700uF stiffening caps in series between a piece of equipment and the wall socket it is plugged into (One on + line, on one - line), what kind of effect would it have?

thylantyr
11-04-2005, 05:00 PM
120VAC -> 700uF capacitor -> load

According to this calculator;
http://www.kusashi.com/reactance-c.php

60hz is the AC wall socket frequency.
700uF is your capacitor

Capacitive Reactance [Xc] = 3.78 Ohms

Equivalent to placing a 3.78 ohm resistor in series with the AC line.

If this is wrong let me know :banghead:

Two 740uF in series would net 370uF and Xc = 7.1 Ohms

If placed across the AC, seems like a 17A draw? /hehe

Alpineinstaller
11-04-2005, 05:03 PM
fun times :)

Raven
11-04-2005, 05:35 PM
That would be wiring the cap directly to the outlet. I'm planning on running it between the wall and a tube amp that doesn't draw anywhere near 17 amps.

thylantyr
11-04-2005, 05:44 PM
That would be wiring the cap directly to the outlet. I'm planning on running it between the wall and a tube amp that doesn't draw anywhere near 17 amps.

It won't be a 'stiffening capacitor' in that application :) It's a 'waste of time capacitor'. :D

Also, capacitors have polarity, some don't. Placing polarized capacitors in AC can be bad news.

If you want stiffening capacitors you need to examine the tube amplifier power supply.

You don't think 120VAC x 20A for a typical house circuit is a 'stiff' 2400VA power source for a little tube amp ?

JimJ
11-04-2005, 05:45 PM
Yeah, I'm not exactly sure what the point of this exercise is...:)

Raven
11-04-2005, 09:06 PM
I am looking for an inexpensive way of conditioning the power from a standard 110 outlet to combat brownouts and spikes.

JimJ
11-04-2005, 09:08 PM
Sounds like the power tranny and/or buffer cap aren't doing their job if you're getting lots of inducted noise...

Raven
11-04-2005, 09:35 PM
If by "Power Tranny" you mean the giant transformer that changes the 110AC input to whatever voltage the rectifier takes in, it's very feasable.

If by "Buffer Cap" you mean the giant stiffening capacitors that this thing seems to have one or two too many of, they've already been replaced. Sprague Atoms in their place via tubesandmore.com. =)

JimJ
11-04-2005, 09:36 PM
You have a EL84 single ended pentode amp, right? Post a picture of it, I have basically the same amp I'm restoring as well...

Raven
11-07-2005, 11:10 AM
Pics are easier said than done when you don't have a camera. =(