Resistor Chip Arrays
Product name: LM358 breathing light DIY welding kit
Product model: TJ-56-263
Working voltage: DC3V
PCB size: 42 * 32mm
The light changes gradually from light to dark, and then from dark to light. It feels like people are breathing. It is widely used in digital products, computers, audio, cars and other fields, and has a good visual decoration effect.
Circuit diagram:
Step 1: C1 is equivalent to short circuit at this time, and the output of U1A is equal to the voltage of the third pin of U1A;
Step 2: This voltage is sent to the lower U1B, and the lower positive feedback circuit makes the lower U1B output high level; High level voltage is+VCC;
Step 3: When U1B output is VCC voltage, voltage difference will occur at both ends of capacitor C1. At this time, the following U1B output will charge C1 through R8 adjustable potentiometer, R7 and R6; When charging C1, the current flows through Q1, and the LED light is also on. With the increase of time, the charging current on C1 gradually decreases, and the corresponding LED also gradually darkens;
Step 4: When C1 is fully charged, C1 is equivalent to an open circuit. At this time, the U1A above becomes a comparator. Because the input voltage of pin 2 is greater than the input voltage of pin 3, the output of pin 1 of U1A becomes low voltage 0V;
Step 5: When the output of pin 1 is 0V, the output of U1B below changes to low voltage 0V through positive feedback of U1B below;
Step 6: C1 discharges with U1B below through potentiometer
Step 7: When the C1 voltage is discharged and the voltage of pin 2 is less than 0.5VCC, the voltage of pin 1 of U1A above begins to rise with the discharge voltage of C1;
Step 8: When the voltage of pin 1 of LM358 rises, the output of U1B below will change to the voltage of VCC through the positive feedback of U1B below;
Step 9: The voltage of U1B is changed to VCC voltage, which is to repeat "Step 3" and the f