Astable Controlled by the Light on the 170-point breadboard (MIN192E)

The previous circuit can be controlled by light if we use the LDR as sensor.

It is a multivibrator where the transistors are constantly changing their state of conduction according to the values ​​of capacitors and resistors.

In this case, we have a sensor, the LDR which changes the resistance of one of the branches of the multivibrator in order to modify the speed of the blinks.

In Figure 1, we have the diagram of the light-controlled flasher.

Figure 1 - Flasher controlled by the light | Clique na imagem para ampliar |

The assembly on the breadboard is ​​shown in Figure 2.

Figure 2 - Assembly on the breadboard | Clique na imagem para ampliar |

In the assembly, observe the position of the transistors and the LEDs, because if they are inverted the circuit does not work.

If you want, try other value capacitors to see how they influence the speed of the blinks.

Material list

Q1, Q2 - BC548 - NPN transistors

LED1, LED2 - Common LEDs

LDR - Common LDR

R1, R4 - 1k ohm - resistor - brown, black, red

R2, R3- 100 k ohm - resistor - brown, black, yellow

C1, C2 - 4.7 uF - electrolytic capacitors

B1 - 6 V - 4 batteries

Miscellaneous:

breadboard, battery holder, wires, etc.