Triode tube breakdown

Crystal oscillator

Mobile phone crystal 3.2*2.5mm 3225 26M (26.000MHZ) 7.5PF 10PPM 20PPM 30PPM

Single chip microcomputer STM32L151CCU6

When the base is open, when the voltage applied between the collector and the emitter of the triode rises to a certain extent, a breakdown phenomenon first occurs as shown in Fig. 1. The IC rises rapidly, and after reaching point A, the tube voltage drop suddenly decreases, and the current increases sharply. The segment from A to B is called secondary breakdown and its transition time is in the order of milliseconds. At this time, the triode has a negative resistance effect and can be used to make a relaxation oscillator.

See Figure 2. 220V AC is stabilized by Rl buck, D rectified, and Cl filtered to obtain a stable DC power supply. The power supply charges C2 through R2. The voltage at the C2 terminal begins to rise. When the voltage at the C2 terminal rises to the breakdown voltage of the transistor V, the CE pole of V breaks down. After V breakdown, its resistance between CE is extremely small, and C2 is quickly discharged through the speaker and V. After the end of C2 discharge, V is turned off, and the power supply is charged to C2 through R2. Due to the extremely short turn-on time of V, its power consumption is within the tolerance range and V will not be damaged. When C2 is fully charged again, the V-crossing is turned on once, and the circuit forms an oscillation, which pushes the speaker to make an audio call.

The circuit of Figure 3 is equivalent to Figure 2, and only the connection of the triode is different. The transistor type of this paper is 3DG12. According to the connection method of Figure 2, the breakdown voltage is 30V. According to Figure 3, the breakdown voltage is 7V. Therefore, when the resistance capacitance values ​​are the same, the oscillation frequency of the circuit of FIG. 3 is higher than that of the circuit of FIG. When the power plug is unplugged, the charge stored in C1 continues to supply DC power to the oscillator. As the charge stored in the CI decreases, the frequency of the oscillator gradually decreases. Therefore, the circuit of this article can be used as a hypnosis. Plug the plug into the power supply before use, and then pull out the power plug for a while to use it safely. Choosing the appropriate values ​​for R2 and C2 allows the speaker to emit a sound like a dense to thin and gradually stopped rain to achieve hypnotic sound. The Cl capacity determines the working time of the hypnotic device, and it is possible to increase the time by connecting several capacitors in parallel. When C1 is 22μF, the hypnotic device can work for eight minutes.

Component selection: R1=2.2KΩ, R2=1MΩ, D is 1N4007, Cl=22μF/400V, C2=0.33μF/160V, V is 3DG12, speaker impedance is 8Ω. The C2 withstand voltage is only required to be greater than the breakdown voltage of V. The triode V can be selected from 9013, 9014, 9018 and 3DG series small power tubes, but the breakdown voltage of each triode is slightly different.

This website tries to open micro- and small-enterprise business advertising business; maintenance point recommended items. The fee is affordable and effective! Welcome to contact in QQ or email!

Why do you want to do online advertising contact?