• This is an AC Chopping Circuit.
• The dim level sets where the AC waveform gets chopped on. More of the cycle makes the bulb brighter, less is dimmer.
• (from digikey http://www.digikey.com/ca/en/techzone/lighting/resources/articles/Retrofit-LED-Bulbs-and-Drivers.html)

• Digital Signals. The four signals on the left. They are labelled on the board.
  • Yellow: light dimming signal, comes from Arduino digital pin 11.
  • White: zero-cross signal, goes to Arduino digital pin 2 in.
  • Red: arduino +5V supply.
  • Black: arduino GND.
  • The LED on board should dim or fade along with the AC light source. Fading will not work until AC power is connected, it depends on the zero-cross info from the H11AA1 chip.
• AC Signals. The four white cords on the right. The bottom two cables on the right are the AC plug. The top two are the Bulb. These are labelled on the board, but are partially covered by the large screw terminals.
  • Bottom is AC Power – Neutral.
  • Bottom Middle is AC Power – Hot.
  • Top Middle is Bulb – Hot.
  • Top is Bulb – Neutral.
  • NOTE: For help identifying Hot and Neutral on lamp cord, look here.

Code

• EagleCAD –

• Gerber –

Building the Circuit

Parts

• 33K
• 10K
• 1K
• 470
• 180
• 2.4K
• 0.01uF capacitor
• generic LED
• H11AA1 – Optocoupler AC Input 1 Channel http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_18825_-1
• MOC3020 – DIP-6 OPTOISOLATOR Triac Driver http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_277780_-1
• BTA12-600 – 600 V, 12 A, SNUBBERLESS TRIAC http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2034010_-1