LEDS Flashing circuit diagram

This simple and inexpensive circuit is not just for Christmas! There are only two resistors, transistor such as a BC547 signal a "flashing" LED and a series of "normal" LEDs. The blinking LED operates as an oscillator and changing the transistor on and off, and the transistor switches all other LEDs. An (non-regulated) Power supply 12 V can be used for power.

No current limiting resistor is required in the LED string, because the forward voltages of the LED in the string is added to the supply voltage. If the red LEDs are used, with a voltage drop of 1.65 V, then 12 V supply seven alternatively, use six five green yellow (2.1 V each) or (2.7 V ). You, of course, you can always mix colors.

Solar garden lights circuit

Solar garden lights circuit

The solar panel  provide 5.5 V and 150 mA. Assuming 3.7V/1500mAH battery charging is complete in 8 hours at 200% capacity at 180 mA. With 10 LED energy consumption would be 90 mA / hour provides a 10 hours lighting light levels 50 lumens to 60 lumens. LEDs 20 the light intensity will be from 100 to 120 lumens.

LED powered at 220 Volts

LED only works at low voltages and still need to use a series resistor. Not a good idea to limit the current at higher voltages using a resistance due to the power dissipated will be too high and the resistance will burn.

LDR switch circuit diagrams

LDR switch circuit diagrams

It is a light switch or light activated relay circuit. Relay when uncovers LDR and relay when covered. Adjust VR1 for light sensitive. LED is lit simultaneously with the relay.

Light Operated Relay Circuit Schematic

Light Operated Relay Circuit Schematic

LDR is used as the light sensor. Low resistance of about 100 ohms in bright light, but increases to 10 megs or more in the dark. Pre-set VR1 sensitivity LDR. LDR will perform during the day so that you will not get T1 gate bias on the base. Therefore, the relay remains deactivated. When the light intensity is reduced, LDR provides more resistance and more current passes to the base of T1 and is being carried out. Then switch to the deportation of pregnancy. Adjusting VR1 to move the relay, especially in the light level. LED indicates the relay activation