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LC tank circuit at resonance

hello,

I have been reading on the LC parallel tank circuit. I have installed on my breadboard an inductor and a small Ac capacitor, I hooked it up to my frequency generator at 5vac. I was expecting to seen the voltage rise at resonance, but I was never able to get more then 3 volts. from what I have been reading, voltage is basically amplified at resonance frequency. is there more to it ? I just have two components in the circuit, I mean it is not complicated circuit, so why doesn't the voltage rise to 10 or 20 volts ??? thanks K

Reply to
lerameur
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"lerameur"

** Try again with the L and C connected in series.

Then measure from ground to the mid point.

...... Phil

Reply to
Phil Allison

HI Phil

I put the cap and inductor in series like you said and it does work, thanks, I get almost double the amplitude. But how do I make it work having the cap and inductor in parallel ?

K
Reply to
captoro

"captoro" "Phil Allison" "lerameur"

I put the cap and inductor in series like you said and it does work, thanks, I get almost double the amplitude. But how do I make it work having the cap and inductor in parallel ?

** You have to feed a parallel LC tank from a current source.

Using a voltage source like you have will never work.

..... Phil

Reply to
Phil Allison

What are the component values for the L and C? Are you sure that your frequency generator range is covering the resonance frequency? (Be sure to distinguish between Hertz and Radians per Second).

Since you're driving the circuit with a (presumably) low impedance voltage source, that source is going to do its best to maintain its 5V across the circuit regardless of the circuit's impedance. Place a resistor in series with tank circuit to provide another place for voltage to be dropped, then sweep the frequency and measure the voltage across the tank.

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Reply to
Greg Neill

By measuring the current rather than the voltage. Series LC amplifies voltage, parallel RC amplifies current.

Reply to
Nobody

Nobody, it's not quite correct to call this amplifcation. It's just energy storage. The L and C are storing energy from previous cycles.

George Herold

Reply to
ggherold

parallel LC acts like an insulator at resonnance and like a conductor elsewhere,

easiest way to see a peak at resonance is to put a resistor in the feed

R in ---/\\/\\/---+-----+----- out | | 3|| --- L 3|| --- C | | +-----+ | ----- /////

Reply to
Jasen Betts

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