LC circuit advice

tangwei8802429

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How can I modify this circuit to generate a 25K sine wave?

maychang

BU406 is a high-power bipolar tube. Why do we need to use such a large power dissipation tube to generate oscillation? Does it require a large output power?

maychang

The frequency of 25kHz is only slightly higher than the audio range. For such a low oscillation frequency, it is not suitable to use an LC oscillation circuit. It is best to use an RC oscillation circuit.

qwqwqw2088

It is also related to the PWM2 signal

tangwei8802429

maychang posted on 2018-8-12 07:02 The frequency of 25kHz is only slightly higher than the audio range. For such a low oscillation frequency, it is not suitable to use LC oscillation circuit, and it is better to use RC oscillation circuit.

OK, the main consideration is not to change the circuit too much, so that it can be shared; thank you for your advice.

maychang

tangwei8802429 posted on 2018-8-12 19:44 OK, the main consideration is not to change the circuit too much, so that it can be shared; thank you for your advice.

"The main consideration is not to change the circuit too much" That is impossible. If it is changed to RC oscillation, the whole circuit must be torn down and rebuilt. You'd better make your requirements clear and complete before you can get "guidance".

tangwei8802429

maychang posted on 2018-8-12 19:56 "The main consideration is not to change the circuit too much" That is impossible. If it is changed to RC oscillation, the whole circuit must be torn down and rebuilt. You'd better state your requirements...

This circuit has an output frequency of several hundred K, and then I want to add a 25K output. Switch between the two frequencies through a relay.

maychang

tangwei8802429 posted on 2018-8-12 22:04 This circuit has an output frequency of several hundred kHz, and I want to add a 25K output. Switch between the two frequencies through a relay.

The RC oscillator can generate a sine signal of up to 1MHz, and it can even be higher, reaching several MHz if it is carefully made. The lowest sine signal can be 1Hz or even lower. If you want to make an oscillator circuit that can switch the frequency between hundreds of kHz and tens of kHz with a switch, it is better to use an RC oscillator circuit than an LC one.

tangwei8802429

maychang posted on 2018-8-13 08:40 The RC oscillator can generate a sine signal of up to 1MHz. If it is carefully made, it can even be higher, reaching several MHz. The lowest can generate 1Hz or even lower...

Well, I will look up the information and modify the circuit to try it out. Thank you.

maychang

tangwei8802429 posted on 2018-8-13 23:55 Well, I'll check the information and modify the circuit to try, thank you.

The frequency range of commercial high-frequency signal generators (continuously adjustable frequency, LC oscillation) is usually from 100kHz to tens of MHz, and there are no products with the lowest frequency below 100kHz. The frequency range of commercial low-frequency signal generators (also continuously adjustable frequency, RC oscillation) is usually from 1Hz to 1MHz. You require a switch to switch between the two frequencies of tens of kHz and hundreds of kHz, so it is obviously more appropriate to use an RC oscillation circuit. Low-frequency signal generators that generate low-frequency sinusoidal signals usually use a Wien bridge oscillation circuit.

tangwei8802429

maychang posted on 2018-8-14 08:24 The frequency range of commercial high-frequency signal generators (continuously adjustable frequency, LC oscillation) is usually from 100kHz to tens of MHz, and the lowest frequency is not seen at 100kHz...

... ...It seems that the teacher has not taught this circuit. I need to review the mathematics... ...

maychang

tangwei8802429 Published on 2018-9-19 21:11 ... ...It seems that the teacher has never taught this circuit. I need to review the math... ...

I suggested using the Wien bridge oscillator circuit on the 10th floor. This circuit can be found in almost any analog circuit textbook.