Large Value Caps

[col]

I read in an old model railway mag how to use one of the power back up caps that are used in computers to smooth supply to the motor and to induce an electonic momentum to the train i.e when power is applied nothing happens until the cap charges up enough to allow ~5v across the motor and then it comes to a stop slowly once power is removed as the cap discharges. The rest of the article seemed a bit pointless as the cap operates at a maximun of 5.5v which is just enough to get most motors turning and it's not reversible.
2 main questions from this. Is there any way to use one of these 1F or higher value caps across a power supply to get rid of crackles as leads get booted around the stage. (Even if you don't habitually boot your equipment, the drunk joker who gets on stage invariably does). If so, how do we deal with the 9v? Are there any that will work with 9v?
Also, can a non-polar cap be made by combining two back to back and if so will this affect the voltage that can be applied across them? Could it then be used to power an electric motor?

Col

[John Lyons]

Would the cap affect anything?
It's only dealing with DC voltage applied to the pedal.
The crackle isn't anything dealing with that I don't think.
Is it?

John

[head_spaz]

A large cap addresses the symptom rather than the problem.
I suspect that your crackle is due to an intermittent connection between your input / ouput jacks and the cables.


The most common style of jacks (shown above) employ a round hole that's supposed to make contact with the sleeve on the plug.
It stands to reason that the hole in the jack must be larger in diameter than the sleeve on the plug, or the plug wouldn't fit into the jack. And that large hole is the problem, because the plug can rattle around in the hole... causing intermittent contact which leads to crackles.

And the problem is exacerbated because most pedals use the sleeve and ring contacts as a power switch. An intermittent connection there would cause crackle due to both intermittent power and intermittent signal.

One solution might be to replace the old jacks with the newer plastic type (shown below), where the sleeve connection is handled by a  dedicated spring contact, rather than a loose... rattly hole.


Try it and see for yourself.

[Brymus]

I read in an old model railway mag how to use one of the power back up caps that are used in computers to smooth supply to the motor and to induce an electonic momentum to the train i.e when power is applied nothing happens until the cap charges up enough to allow ~5v across the motor and then it comes to a stop slowly once power is removed as the cap discharges. The rest of the article seemed a bit pointless as the cap operates at a maximun of 5.5v which is just enough to get most motors turning and it's not reversible.
2 main questions from this. Is there any way to use one of these 1F or higher value caps across a power supply to get rid of crackles as leads get booted around the stage. (Even if you don't habitually boot your equipment, the drunk joker who gets on stage invariably does). If so, how do we deal with the 9v? Are there any that will work with 9v?
Also, can a non-polar cap be made by combining two back to back and if so will this affect the voltage that can be applied across them? Could it then be used to power an electric motor?

Col

I added a 2200uf as a filter cap on my breadboard circuit I am doing at the moment.(It was handy)
I noticed when switching the circuit off it takes about 2 seconds to power down due to the large cap discharging.
I think this is what you are asking?
So yeah that would help with a very short cutoff at the DC jack, MAYBE enough to hide it...
I would think a 10,000Uf would take even longer.
That and better jacks would probably solve your problem.
I cant see putting 1Farad caps in a pedal how would you fit them in w/o a bigger enclosure?