Rusty wires and poor connections causing capacitative effect?

[ki-unistudent]

Hi all!

I am running an experiment in which I have rigged up a circuit to anodise aluminium foil. Running it with a constant voltage of ~40V I have found that rusty wires, poor connections (I am using alligator clips) and even using stackable banana plugs causes erratic (and high) currents which ruins my samples. With my limited knowledge in circuitry, all of these things might be modeled as resistors restricting the flow of electrons; however if they merely acted as resistors I cannot see why this should cause erratic current behaviour and shouldn't they reduce the current rather than increase it? Is it possible that they act as capacitors, "storing" the electrons and then releasing them sporadically causing current peaks?

While I'm at it, would anyone have any idea about how to symbolically represent an electrolytic bath in a circuit schematic? (Would I represent the anode/electrolytic bath/cathode assembly as a capacitor in itself?)

Thank you all in advance.

 

[mfb]

Even a perfect capacitor does not conduct "more" than a regular wire.
There could be some inductance in the circuit - together with unreliable connections, this could lead to high voltages (and currents).
As a work-around, you can connect a capacitor in parallel to the electrolytic bath.

While I'm at it, would anyone have any idea about how to symbolically represent an electrolytic bath in a circuit schematic?

I would just invent a symbol (roughly representing two wires going into that bath).

 

[jim hardy]

Wow would you post a link to the basics of what you are doing?
I have some interest in amateur electrofinishing.

40 volts sounds to me like an awful lot for a cell.
Would you perhaps post asketch of your setup?to other question: I've seen electrolytic cells in very old equipment (1940's) represented as a dot and partial arc

sorta " ° ) " but the dot more centered in arc

perhaps surrounded by something resembling a test tube.
Before Autocad draftsmen were more artistic.

 

[NascentOxygen]

With my limited knowledge in circuitry, all of these things might be modeled as resistors restricting the flow of electrons; however if they merely acted as resistors I cannot see why this should cause erratic current behaviour and shouldn't they reduce the current rather than increase it?

You're not mistaking the overshoot of a mechanical meter's needle as indicating a momentary overcurrent, are you?

The current in a cell is greatly hindered by gas forming on the electrodes and causing an insulating layer (partially). This gas disperses with time, and is not present at startup. So if your connectors cause a high resistance, gas liberation decreases, then when good connection is re-established, there is a short higher current burst before gas buildup again hinders current flow.

Rusty wires and poor connectors do exhibit capacitive effects at RF but not at the frequency you are using.

Good luck with your explorations!

 

[alphy]

Hello,

Thank you for sharing your experiment and observations. It is certainly possible that the rusty wires and poor connections are causing a capacitive effect in your circuit. Capacitance is the ability of a system to store an electrical charge, and this can occur in situations where there are two conductors separated by an insulating material, such as the oxide layer on the surface of the aluminum foil in your experiment.

When there is a poor connection or rust on the wires, it can create small gaps or areas of high resistance, which can act as a dielectric material and cause capacitance. This can lead to the erratic behavior and high currents that you are observing.

To address this issue, you may want to try using clean and properly connected wires and connections. You can also try adding a capacitor in your circuit to help stabilize the current and reduce any spikes. As for representing the electrolytic bath in your circuit schematic, you could potentially use a capacitor symbol to represent its capacitance, but it may also be helpful to add a note or label to indicate that it is the electrolytic bath.

I hope this helps and good luck with your experiment!