Flashing LEDs toy with 555


Posted on May 26, 2012

There have described the involvement benefited LM3909 circuit, which is quite expensive. That's why I prefer to use a much cheaper known timer 555th.Involvement of the tree is a very simple scheme is to figure 2 . It is based on several multivibrator used as a favorite flasher timer 555 in the simplest possible involvement. Each flasher controls six light emitting diodes, of which only D3 and D6 are on the same PCB. The signal output from the IC (pin 3) is fed through resistor R1 to capacitor C1. When power to the IC output voltage appears to be approaching the positive supply voltage.


Flashing LEDs toy with 555
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Flashing LEDs toy with 555 - image 1
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At this time, light is off. Capacitor C1 charges through resistor slowly until it reaches the voltage on the 2 / 3 voltage. Then they tilted the internal comparator and RS flip-flop. IC output voltage is reduced to zero and the LED lights up. Capacitor C1 now discharges through resistor R1 to the output IO. When the voltage on the capacitor C1 is reduced to 1 / 3 supply voltage reverses, the second internal comparator and flip-flop RS is brought to its original state. The voltage at the output of IC increases, the LED will turn off and the capacitor starts to charge again. The whole cycle is repeated periodically, the voltage on C1 ranges from 1 / 3 2 / 3 voltage. Voltage level 1 / 3 and 2 / 3 supply voltage for the comparators are set resistors inside the IC. The flasher was difficult to use the normal timer with the involvement of a discharging transistor. It does have a much better frequency stability, however, is complicated by one resistor. Frequency stability of this design is not important. The increased current consumption LED is not suitable timer 555 in the CMOS implementation. The capacity of capacitor C1 and resistor R1 affects the frequency of flicker. For Christmas tree blink intermittently if possible, choose for each "branch" another resistor R1. The assembled sample I chose R1-82, 100, 120, 150, 180 and 220 kOhm. To exit the IO LEDs are connected via resistors R2 and R3. These resistors limit the current...




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