You've got the signal generator connected properly, but you have the scope ground connected to the LC junction. It should go to the signal generator ground.
You're using an electrolytic capacitor when you should be using something non-polarized.
--- Sorry, I have Java turned off.
---
--- Copy the circuit list using a text editor like notepad, then save it to any convenient folder using a filename that ends in .asc, say LC.asc.
Once it's saved, left click on the file and LTspice should launch itself, find the circuit list, and display the schematic.
If it doesn't, then launch LTspice, navigate to the file and left click on it. The schematic will appear and if you want to run the simulation either left click on the running man icon on the menu bar or right click on the gray background of the schematic and then left click on RUN.
I have it set up to display an AC analysis and have put a small (0.1 ohm)resistor in series with the AC source so that both the voltage peak at the LC junction and the dip at the top of the inductor can be seen.
Enjoy! :-)
-- JF
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J
Jamie
50 ohm ___ scope tip here +---------+|___|+-----------+ 4825 hz AC signal | | | | --- --- 3.3 uf np + | | | C| C| 330uh C| | + | | | + GND scope common/grd. (created by AACircuit v1.28.6 beta 04/19/05
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F = 1/Sqrt(L*C)* 6.28
When this circuit resonates, you should see a minimum dip where idicated.
Most likely the components are not exact, along with your signal gen. So you'll need to move the freq around a little.
Jamie
P
Phil Allison
"Jamie"
** And you will see peaking if you probe across just the inductor.
Anecdote:
I used this kind of set up once to test some class X2 mains caps.
Using a 5.6mH air cored inductor and a 47nF mains cap driven by an audio amplifier of about 50 watts capacity it was easy to get up to 500 volts AC across the cap at about 10kHz.
This equates to about 1.5 amps of current through the cap and it did not like that one bit.
In fact it was fuming.
... Phil
C
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ted.
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Hi,
I posted some of my inductors and capacitors
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I prefer to use a tank circuit, but for now just trying to get anything into oscillation is impossible. I have your simulation running. I do the same circuit. The practical part is just not working. What other information do you need?
Ken
P
Phil Allison
"George Herold"
** I used an 8 ohm dummy load in series to protect the amplifier from harm when the cap flamed and shorted.
The purpose was to see what sort of film caps were best at surviving full power oscillation at 50 to 100kHz from a 1000 watt when used in the output zobel network.
.... Phil
P
Phil Allison
"Phil Allison"
G
George Herold
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Zobel network =3D> matching impedances, RC=3DL/R? I drive helmholtz coils (~1 ohm resistance) through a series 10 ohms paralleled by 10 ohms and C.
If you flip the B field fast enough you can leave the spins behind. (change the B field slowly and spins follow) slow and fast depend the precession rate. Energy =3D (u)magnetic moment times B.
Which is cool because you can't drag spins through zero magnetic field.
George H.
J
John Fields
Copycat.
J
John Fields
With a 50 ohm source, you won't.
P
Phil Allison
"John Fields"
** Hmmm - so maybe this is the OP's real issue.
With a 50 ohm source and *series" resonance - there is a large voltage drop at resonance that cancels any voltage boost across the reactive parts.
Drive the same circuit with an audio amplifier and you will see peaking.
... Phil
J
John S
But your diagram was too complicated for him to pick up on it.
Is that a big steel bolt through the centre of your inductor? If it is, you might get very different responses, particularly, at the higher frequencies, if you remove it.
E
ehsjr
I get the feeling that you are not using a frequency generator that applies the proper frequency to the input of the RLC circuit. Put your scope probe on the generator output with the ground clip on the generator ground. Vary the frequency from
100 Hz up to 10 kHz and watch the scope to verify that your generator covers that range. If it doesn't, then the problem is with the generator. Once you verify that the generator yields useful sine wave output over that range, connect your 50 ohm resistor across the generator output and verify again that the generator covers the range. It's possible that the generator is defective and can't drive the load.
Once you know your generator is working, connect your _five_ uF cap in series with your 330uH from delavan. It _must_ be a known value of 330 uH - you said "I then decided to use commercial inductor like a 330uH from delavan". The word "like" in your sentence means we don't know for a fact that the inductor _is_ 330 uH. And I emphasize using the 5uF cap, because we know that one is non-polarized, from the link you posted earlier in the thread. We don't know what the
3.3uF is.
With 5uF and 330uH your resonance should be ~3918 Hz. Parts tolerance may take the resonance away from 3918 some, so vary the generator frequency a few hundred Hz on either side to find the resonant frequency.
Maximum current will be drawn through the resistor when the signal generator is set to the resonant frequency in the circuit:
Sig Gen---Resistor---Cap---Inductor---Gnd
With your scope probe connected between the resistor and the capacitor, and with the ground clip connected to ground, the smallest amplitude waveform on the scope screen results when the generator is tuned to the resonant frequency.
Once you have found resonant frequency with the above procedure, and using *known* values of L and C, you can then use the same technique to find unknown values. You can resonate an unknown C with a known L (or vice-versa) and do the math to find the value of the unknown component. Note, however, that the unknown L and C you use may resonate outside the range your signal generator can cover. Always check that your generator actually puts out a good signal under load at the frequency range of interest.
Ed
G
George Herold
=A0 =A0 =A0 =A0 =A0 =A0scope tip here
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Are you probing between the L and C? Can you put the drive waveform on the 'scope too? Do you see a peak? One nice thing about having the drive on the same 'scope display is the phase relationship tells you something too.
George H.
J
Jamie
No other information is needed.
I am done.
Jamie
C
captoro
=A0 =A0 =A0 =A0 =A0 =A0scope tip here
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=A0 =A0 =A0 =A0 =A0 --- 3.3 uf np
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Anybody lives in the montreal area?
K
J
John S
No. They moved and left no forwarding address.
C
captoro
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.
age drop
ts.
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.
Anybody lives in the montreal area?
K
C
captoro
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.
age drop
ts.
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.
Anybody lives in the montreal area?
K
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