LED flash circuit using driver transistor

You may wonder how a transistor can be used to form an oscillator circuit? But it is just a transistor. The key is that a self-flashing LED is used in the circuit.

This flash circuit uses a single driver transistor (transistor), and the flash frequency depends on the self-flashing LED. The LED driven by the transistor in the photo is a high-brightness white LED with a diameter of 3mm, and its brightness can be adjusted by changing the 100uF electrolytic capacitor, 4K7 resistor or 10K, 1K resistor.

The 1K resistor is used to discharge the 100uF capacitor so that when the transistor turns on, the charging current causes the white LED to glow. If this resistor is replaced with a 10k resistor, the capacitor will not be fully discharged and the LED will flash at a lower brightness. All components are fully shown in the photo, and it is easy to see how to connect the components by comparing them to the circuit diagram.