This 8 function serial Christmas lamp controller is based on the IC UTC 8156 from Unisonic. Specially designed for the same purpose, the UTC 8156 can control the four lamps in 8 modes namely waves, sequential, slo-gol, chasing/flash, slow fade, twinkle/flash, steady ON and auto scan. Control signals for controlling the lamps will be available at pin 12 to pin 15 of the IC. SCRs are used to drive the lamps according to these control signals.
Circuit diagram.

8 mode christmas lamp


  • The circuit can be assembled on a Vero board.
  • L1 to L4 can be 230V/40W lamps.
  • H1 to H4 can be TYN612 SCRs.
  • Heat sinks are recommended for the SCRs.
  • IC1 must be mounted on a holder.
  • If 1A bridge is not available, make one using four 1N4007 diodes.
  • S1 can be an 8 through rotary type selector switch.
  • S1 can be used to select the modes.



  1. Can these be run at 120v? How many strings can be run in series?

  2. Error in the application diagramm, compare this with datasheet IC. Ground is connected to negative pin of diode bridge. R2 connected to lover wire AC.

  3. I see that to choose the various modes in the chip essentially a rotary switch capable of creating contact with pins 1 to 8 is required. How then are the Chinese light controllers I have work with just a push button that creates a momentary contact.

  4. I need help with something related to this. I bought a couple of led xmas lights using a 8 function mini controller. I opened it up and it looks similar to this. I installed it just below the roofline, so I attacked a switch lower to the ground. I noticed that if left switch off for a long period of time the light revert to the original setting of combination (all sequences will be played in intervals) when I had set it to steady on. Since it is too high to reach the controller every time is there a way to keep it steady on by uhmm I don’t know maybe cutting a connection or jumping one? Any help would be great. Thanks


    please tell me, I want use this on LED running on 12volt DC.

    thanks & regards

  6. surya prakash

    very interesting and simple decoration project , i was searching for this type circuit.
    can you design PCB layout for this project.

  7. seetharaman

    Hi Patrick yes you can. it is not going to improve anything in the operation

  8. seetharaman

    Hi Tobi BC109 is a small signal low noise amplifier in TO18 metal casing for input stages. BC549 is the plastic equivalent. BSY & BFY are almost same but for better switching charecterestic of BSY. BFY is a higher frequency transistor with lower input capacitance. Please refer nxp manual.

  9. what is the equivalent of BC109 IC. BSY51 and BFY51 transistor, are the same?

  10. hullo, thanx for the circuit but what can i use as an alternative for ic 8156?

  11. Hi ok thanks a lot everyone. I will try RS components. No I am not in India I am on a small island in the mediterrenean sea. thanks again

  12. seetharaman

    Hi AD You can try in RS components. if in India try Visha Kits or Vega Kits, Mumbai. You can use any sensitive gate thyristor to suit your requirement, as this IC can give an output drive of 0.2mA only.

  13. So can I change the triac model so I can have more power? because I cannot limit myself to just 40 bulbs. Another problem is that I cant find a shop to buy this IC. if any of you have a site and can post me the link I would be very very grateful. Thanks all

  14. seetharaman

    Hi AD you can use 10nos 230volt 40watts lamp in parallel per channel not more than that say if the Triac used is TNY612. in 4 channels that is a total of 40 lamps.

  15. So I can put for example 25 230/40W on each channel ? sorry I am not such a pro for circuits

  16. How many light bulbs can I add to this circuit ? Is tere a limit? and how do I connect say 100 lightbulbs?

    • Reply to Ad
      As the diagram shows you can add only four channels to this circuit. The number of bulbs (in parallel) per channel channel depends on the current rating of the corresponding triac. You can choose any number of bulbs ( in parallel) per channel but the load should should not exceed 400W (for TYN612).


    very intresting circuit.I want so much IC based blinking circuit like this for dacoration.

  18. Dick Rodriguez

    Does anybody knows were can I buy the utc 8156?