Detailed explanation of ambulance electronic flash signal circuit diagram

Hospital ambulances generally use blue mechanical rotating lights. This article uses 16 ultra-bright blue LEDs arranged in 2 sections and 4 in a group. A total of 4 groups of LEDs are arranged in a circle. Replace mechanical rotating lights with cyclically segmented lighting to create a rotating effect.

The principle circuit is as shown in the attached figure, in which the +12V terminal is connected to the positive electrode of the ambulance battery (12V), GND is connected to the ground wire, and terminal A is connected to the door switch. Before the ambulance door is closed, the door control switch S2 is turned off. After closing the door, S2 is linked to close. At this time, if the power switch S1 is turned on, the ③ pin of the bistable flip-flop composed of N1 and N2 will output a high level and send it to the oscillator N3 ⑧ pin to make it in the working state. Its oscillation frequency is determined by C2, R3 and RP time constant. It is adjusted by RP to control the rotation speed of the signal light. The oscillation signal is sent to the CP end of the decoding output octal counter IC2 (CD4022) as a clock control signal. Make Y0~Y3 output positive pulses in sequence, VT1~VT4 turn on in turn, and LED1~LED16 light up in sequence. Forming a blue rotating halo. Each group of LEDs is divided into two segments, and both segments emit light at the same time. The lighting sequence is:

1.LED1, 2→LED5, 6→LED9, 10→LED13, 14→LED1, 2…. .

2.LED3, 4→LED7, 8→LED11, 12→LED15, 16→LED3, 4…. . .

After the ambulance stopped. As long as the door is opened, S2 is disconnected by linkage, N1 and N2 are reset to the initial state, N2 ③ pin flips to low level, N3 ⑧ pin is closed to stop vibration, and the blue signal light stops rotating. At this time, S1 is turned off. Cut off the 12V power supply. For realistic results. High quality reflectors can be added.