LED Fading Effect / LED Strobe using 555

  • Rajkumar Sharma
  • 1199
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  • easy
  • Tested

In general, generating an LED fade effect requires a microcontroller or another expensive circuit. We have built this low-cost LED fading board using an inexpensive 555 Timer. The 555 timer is used as an astable multivibrator, which generates low-frequency pulses, further, this pulse train is feed to the base of BJT transistor TIP122 with a series resistor along with a high-value electrolytic capacitor. The combination of resistor R5 and capacitor C6 at the base of Q1 gradually increases and decreases the base voltage which provides soft ON/OFF (Ramp) to the load. The circuit can drive a load up to 18W without heatsink. An onboard potentiometer is provided to adjust the frequency of flash. Connector CN1 DC is for 12V Input, Connector CN2 is provided to connect the LED. This circuit also can be used as a LED Strobe Light and covert a regular 12V LED Light into a Flashing Strobe Light with few changes of components.

This circuit can be used as a high-power LED Strobe with the following modifications:

  • Do Not Populate C6
  • Use R5 2K2 Ohms SMD Size 0805
  • Use R6 0 Ohms
Note 1: This circuit can drive 12V LED directly, thus use R1, R3, R4 at 0 Ohms, to drive bare LED choose appropriate series resistor R1, R3, and R4 as per LED load current requirement.
Note 2:  The circuit is built for low-frequency operation, to use as a high-frequency flasher choose C4 10uF /25V or lower capacitance.

Features

  • Operating Supply 12V DC
  • Load 1.5A Continues (Max)
  • Frequency 1Hz to 5Hz Adjustable (Approx.)
  • Header Connector for Power Supply and LED
  • Large Thermal Area on PCB provided for heat decapitation
  • PCB Dimensions 60.48x 49.53 mm

Schematic

Parts List

BOM    
SR.QNTY.REF.DESC.VENDOR/DIGIKEY/MOUSER
11CN14 PIN MALE HEADER 2.54MM PITCHDIGIKEY S1011EC-40-ND
21CN24 PIN MALE HEADER 2.54MM PITCHDIGIKEY S1011EC-40-ND
32C1,C50.1uF/50V SMD SIZE 0805YAGEO
41C2DNPOMIT
51C3100uF/16V SMD SIZE 1210YAGEO
61C4100uF/25V OR 16V ELECTROLYTICDIGIKEY 493-13451-1-ND
71C6220uF/16V OR 25V ELECTROLYTICDIGIKEY 732-8797-1-ND
81PR1100K PRESETDIGIKEY 3362P-104LF-ND
91Q1TIP122DIGIKEY 497-2543-5-ND
103R1,R3,R40.1E OR 0E 5% SMD SIZE 2512YAGEO
111R210K 5% SMD SIZE 0805YAGEO
121R533K 5% SMD SIZE 0805YAGEO
131R60E SMD SIZE 0805YAGEO
141U1NE555 SOIC8DIGIKEY 296-6501-1-ND

Connections



Gerber View

Photos

Video

NE555 Datasheet

ne555

PCB

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