CD4017 fish tank oxygen pump control circuit

Most fish tank oxygen pumps pass the mains electricity through the coil to generate an alternating magnetic field, which interacts with the permanent magnet and pushes and pulls the leather cup to generate pressure. The detailed process will not be repeated. A few years ago, I used an oxygen pump and found it noisy, so I made improvements. I would like to organize the circuit for reference.

50Hz is considered a low frequency for electronics; for the mechanical movement of the oxygen pump, 50Hz is too high. Through circuit control, the working current waveform shown in Figure 1 is generated. When a positive half-wave ① passes, the next negative half-wave ④ passes; then the next positive half-wave ⑦ passes, and the cycle repeats. The control circuit is in the off state at other times. The specific circuit uses a CD4017, see Figure 2. The circuit wiring is similar to a switch, which can be connected in series to the oxygen pump circuit.

After full-bridge rectification, a DC pulsating voltage is obtained. The power supply is rectified and then stepped down by a 220KΩ resistor. The voltage is divided by the resistor at the counting end. The part higher than the power supply voltage (this is indispensable and is also to protect the CP end of IC) is used to trigger the thyristor to conduct, which is equivalent to 1 and 4 in the waveform. Q6 outputs a high level at the waveform 7 above, triggering IC to reset, and Q0 outputs a high level, and the cycle repeats.

When the circuit is just powered on, it will take about 1 to 2 seconds for the filter capacitor to charge before it can output, which does not affect the use. Therefore, the CR terminal of IC is not set to power-on reset.

The actual use effect is that the vibration and noise of the oxygen pump are significantly reduced. When touching the shell during use, the temperature rise is much smaller, and the amount of bubbles is slightly less than before. Visually, it is about two-thirds of the original amount of bubbles.