LED Flasher using NE555

LED Flasher circuit using NE555 timer IC

• R1, R2, C1 and the supply voltage determine the flash rate. For a variable flash rate, replace R1 with a 1 MΩ pot in series with a 22k resistor.


• The purpose of R3 and R4 is to limit current through the LEDs to the maximum they can handle (usually 20 milliamps). 470 ohms works well with a supply voltage of 9-12 volts.


• The duty cycle of the circuit (the percentage of the time LED 1 is on to the time it is off during each cycle) is deterimed by the ratio of R1 to R2. If the value of R1 is low in relationship to R2, the duty cycle will be near 50 percent.


• The NE555 timer chip can be damaged by reverse polarity voltage being applied to it. You can make the circuit fool proof by placing a diode in series with the supply leads.

10 Stage LED Sequencer

Circuit diagram

Components

1. IC1- CD4017


2. IC2- NE555


3. C1 - 1μ


4. C2- 0.01 μ


5. R1 - 470 Ω


6. R2 - 100 KΩ


7. R3- 100 Ω


8. LED1-10 - RED LED


9. 9volt DC power supply.

For power supply you can use 9volt battery or can design separate power supply using step down transformer and 1N4007 diodes.

Lamp Dimmer

12v LAMP Dimmer


[caption id="attachment_82" align="aligncenter" width="308"] 12v Lamp Dimmer[/caption]

Parts

1. IC 1 – NE555


2. Transistor – 2N2955 -1


3. Resistance – 1k(2 no.), 100 Ω


4. Variable Resistance – 50k


5. Capacitor – 0.1 µF


6. Diode – 1N4001 – 3


7.  12v 2 amp Bulb

Input Voltage is 12v. To create your own bench top power supply use the circuit shown in http://electronichobbyist.wordpress.com/2012/06/17/regulated-dc-power-supply-circuit/