# LC parallel tank circuit

Moderator
Nov 8, 2019
3,079

#### Rajinder

Jan 30, 2016
568
Hi all,
I have attached a simulation in Simetrix, as you can see the voltage is at a minimum on the resonant frequency. What have i done wrong? The 1K was added to create a voltage to be monitored.

#### Attachments

• lc tank.pdf
11.3 KB · Views: 6
• LC Parallel.pdf
414.4 KB · Views: 4

#### WHONOES

May 20, 2017
1,217
The LC circuit should be in series with the 1K resistor as previously stated.

Edit: Have just seen your pictures. The response is correct. I intended you to put the 1K resistor on the top of the LC circuit so that it goes to the + arm of the ac source. It would then give the response previously described.

#### Rajinder

Jan 30, 2016
568
The LC circuit should be in series with the 1K resistor as previously stated.

Edit: Have just seen your pictures. The response is correct. I intended you to put the 1K resistor on the top of the LC circuit so that it goes to the + arm of the ac source. It would then give the response previously described.
Hi
Just to confirm the resistor should be placed in between the lc parallel circuit and the sine wave generator?
I will try this. However, i have seen the configuration that i have shown in a text book, hence the confusion.
I will give it a try.
Thanks

#### Rajinder

Jan 30, 2016
568
Hi,
I have just tried putting the resistor in series (see attached schematic and output - LC Parallel Circuit.pdf). It shows voltage at a max and current at a minimum as you mentioned.
I took this a bit further by adding a transistor (see attached schematic - LC Parallel with Transistor). I am not sure that is the response, I think it may be as the LC is a high impedance circuit hence passes everything out of the collector of the transistor, is that correct? is there a better way to test the second circuit?

Any help would be appreciated.

Best regards,
Raj

#### Attachments

• LC Parallel Circuit.pdf
180.4 KB · Views: 5
• LC Parallel with Transistor.pdf
173.4 KB · Views: 3

#### WHONOES

May 20, 2017
1,217
Your circuit won't do much as the transistor is not properly biased.

See PDF's attached.

#### Attachments

• Tuned cct test.pdf
10.6 KB · Views: 7
• Tuned cct test graph.pdf
40.2 KB · Views: 6

#### Rajinder

Jan 30, 2016
568
Your circuit won't do much as the transistor is not properly biased.

See PDF's attached.
Hi,
Thanks for the reply and the pdf documents. Really appreciate you taking time out to help.
I have just wired the LC Parallel circuit (as in my message). The scope was placed at the output i.e. across the LC Circuit. However, I saw no change in voltage as I changed the frequency. I sweeped from 100KHz to 350KHz, the resonant frequency should be about 190KHz. Am I not scoping at the correct point?
Thanks for the circuit you sent and graph. I do not fully understand the circuit and the graph, could you give me a brief description. Thanks again.

Jan 30, 2016
568

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