oscillation

[WG1337]

Hi!
I started to read about oscillation and found that electronic clocks are working on oscillation.
So simply oscillation is made with an inductor and a capacitor when they "charge" and "discharge" each other. So I had an idea to make "a timer" which would make a LED turn on every second.
I calculated parameters of the coil needed and used a 22 gauge wire to make a 1cm x 1.3cm x 10 turns coil and wired up a 47nF capacitor @ 16V in parallel with a 3V battery. The LED didn't blink.
I think it was because of I left the capacitor charging, so that would mean that I nead to charge the capacitor and disconnect the power source, but can't this be done with a circuit which would tell if the capacitor is "full"?
P.S. does farads(F) change if I use lower voltage? If one book is correct then no, because 1 farad is such a value that would mean by changing 1 Amp of current would allow to store 1 Volt (may sound weird because it's translated), but that book has many mistakes :/
Also, a diode is a device that allows only current flow in one dirrection, so if I add a diode in AC (I won't do that) that would mean that circuit is cut off when there is a negative flow, like -10V?

 

[MikeMl]

There is more to an oscillator than just a capacitor and inductor. It takes an electronic circuit to supply just enough energy each cycle to make up for the energy lost in the capacitor, inductor, and whatever the oscillating circuit drives as a load. Wiki "Oscillate" for an explanation of how oscillators work.

 

[Miles Prower]

Hi!
I started to read about oscillation and found that electronic clocks are working on oscillation.
So simply oscillation is made with an inductor and a capacitor when they "charge" and "discharge" each other. So I had an idea to make "a timer" which would make a LED turn on every second.
I calculated parameters of the coil needed and used a 22 gauge wire to make a 1cm x 1.3cm x 10 turns coil and wired up a 47nF capacitor @ 16V in parallel with a 3V battery. The LED didn't blink.

Mega problem there. I guesstimate that the coil has about 1.0uH of inductance. If this is off by an order in magnitude, let's say it's 10uH. Given a 47nF capacitor, you have:

w= (LC)^-0.5

w= (10E-6 X 47E-9)^-0.5= 1.46E6 (Rad / Sec)

f= w / 2pi

f= 1.46E6 / (2 X pi)= 232.37KHz

You are way way way off on the frequency, and wouldn't be able to see the LED blink at that frequency.

For frequencies of 1.0Hz, LC tuners are hardly practical propositions. You'd be better off with something that derived its timing from RC circuits (astable multivibrator, 555 timer, etc.) Besides, what you have described won't do more than ring when first connected to the battery, and powering a LED will damp out whatever oscillation (if any) occurs. You still need some sort of active circuit to keep driving that LC tuner.