Tattoo Machine Schematic Design And Sharing?

1. Design of power supply circuit

This system is powered by a single lithium battery with a supply voltage of 3.4-4.2V. The battery voltage needs to be stabilized by LDO to 3.3V to power the MCU. The battery charging circuit uses the 4059 charging solution with a charging current of 1A and a full charge of 4.2V. The battery voltage is detected by the ADC of the MCU. When the battery voltage reaches 3.5V, the battery protection is activated and the machine does not work. The circuit is as follows.

2. Design of motor drive circuit

The motor needs a 12V power supply, so the battery voltage needs to be boosted to 12V. A boost IC (SY7203DBC) is used here. After the battery voltage is raised to 12V, an MOS is controlled by a PWM wave to drive the motor and realize the speed regulation of the motor. Finally, the motor current sampling is completed through the sampling resistor, operational amplifier, and ADC of the MCU. The circuit is as follows.

3. Design of display and indication circuit

The display interface uses an OLED screen, and the LED indication ring is composed of 12 LEDs. When working, it can indicate the charging status with a dynamic water-breathing light, or it can indicate different motor speeds through a static ring display. The circuit is as follows.

4. Design of button circuit

This circuit defines three buttons, one is the power button, one is the speed increase button, and the other is the speed decrease button. In the off state, press and hold the button for 3 seconds, and turn on the machine, the interface statically displays the power for 2 seconds, then switches to the time screen display, the ring speed level is displayed to the 10th level, this is the standby screen, at this time, the motor does not rotate; press the power button again, the default 10th speed level works, and the speed level can be increased or decreased after the tattoo machine is started; during this period, short press the power button, the motor will not rotate, the product enters the pause mode, and the tattoo machine automatically shuts down when the pause time reaches 5 minutes continuously. Press the plus and minus buttons to change the speed of the corresponding motor to fast or slow, and at the same time, the interface ring will also update the display synchronously. If the speed is increased to the 20th level, and the plus key is pressed again, the speed remains unchanged and is still at the 20th level; on the contrary, if the speed is at the 0th level, and the minus key is pressed again, the speed remains unchanged and is still at the 0th level. The circuit is as follows.

5. MCU circuit design

The MCU uses STM32F105R8, and the circuit is as follows.