Equip electric bicycles with brake lights and flashing tail lights

Electric bicycles are fast, quiet, and light and flexible when driving. Most electric bicycles on the market do not have brake lights like motor vehicles, which poses a safety hazard when driving fast. Therefore, installing brake indicator lights on electric bicycles to remind vehicles behind them is of great practical significance for the driving safety of electric bicycles. In addition, I wanted to install a flashing taillight for my car a long time ago, which is beautiful and saves electricity when driving at night. I took the opportunity to install a flashing taillight to kill two birds with one stone. The circuit diagram is as follows:

Working process: During normal driving, since the brake line of the motor controller is at a high level (about 5V), Q1 is turned on, Q2 and Q3 are turned off, and the brake light is not on; when braking, the brake line becomes a low level, so Q1 is turned off, Q2 and Q3 are turned on, and current flows through the brake light to light up. After releasing the brake, Q1 resumes conduction. Q2 and Q3 are turned off to turn off the brake light, thus achieving the purpose of brake indication.

The flashing taillight is a bistable circuit composed of a 555 time base circuit. When the 3rd pin of the 555 outputs a high level, Q1 is cut off and the LED2 light group is off, and Q2 is turned on and the LED1 light group is on; when the 3rd pin of the 555 outputs a low level, Q2 is cut off and LED1 is off. Q1 is turned on and LED2 is on. If it flashes in this order, the flashing speed can be changed by adjusting R.

Installation: Remove the taillight cover, cut the taillight cable, and connect the original taillight (40V/10W is just right for brake light) to the brake light circuit. Connect the flash light circuit composed of 555 to the original taillight cable. The LED light can be installed in the lampshade according to personal preference, such as double ring, double bar, double color line, etc.

After this installation, the original taillight bulb will light up when you brake and go out when you release it. When driving at night, the LED in the taillight cover will flash alternately, which is very beautiful and saves electricity. It is more eye-catching than the bulb taillight before the modification!