So I just made a circuit with a 555 IC, LED, a couple resistors and a 2.2uF electrolytic capacitor. Just to blink an LED on and off.
I bought the capacitor from Ripoff Shack and I have a feeling it was sitting there for a very long time. It was in the back of the shelf and the ESD bag was covered in dust.
So when I first started the circuit the LED kind of went from dim to kind of bright and was very slow, it was really sluggish. After about 5 mins the LED randomly starting running at the correct speed, blinking on and off every second, and is very bright. Like all of a sudden someone just kicked it in the butt.
I'm just wondering why I got that sluggishness at first, .. That's the best way I can describe it. Was that just because the capacitor was really old and needed to be "warmed up" or something?
I left it unplugged for hours and came back, and every time it works perfect now. It only did that during the first start up. I was just curious as to what might have been happening.
Do capacitors need time to adjust or something when they are first used?
Electrolytic capacitors rely on a film of aluminium oxide deposited electrolytically.
In normal operation the voltage helps to form and maintain this insulating oxide layer.
I suspect in storage it had deteriorated and meant the capacitor was leaking
enough to overwhelm the resistors in the RC timing section, but the capacitor
gradually "reformed" and started leaking a lot less.
High voltage electrolytic capacitors have to be reformed after long periods
of storage otherwise the leakage current causes significant heating and may
damage / pop the thing. You just limit the current with an external resistor and
monitor the leakage current as the voltage is increased towards the working
voltage.
So how would I monitor leaking current? With a multimeter some how?
I could just take a capacitor, add maybe a 220 Ohm resistor, and just run power through the capacitor for a few minuets when I pull them out of storage?
So even with a resistor on it, the capacitor would sooner or later reach it's maximum capacity and start to function properly?
The process of reforming an old aluminum electrolytic capacitor consists of the application of rated voltage, through a resistor, for a period equal to five minutes plus one minute per month of storage
...
Note: Apply the appropriate D.C. voltage to the capacitor with a D.C. power supply. An old Kepco, Lamba etc. tube regulated lab power supply rig works great. Be sure to observe the proper polarity!
the "rated voltage" is the voltage rating printed on the capacitor?