I'm using the schematic below to control a lamp (light bulb) with a microcontroller and I'm running the mcu (and moc3010) off of AA batteries. I just realized the moc3010 has an LED in it that needs typically 15ma. I'm assuming this 15ma needs to be applied constantly if I want the lamp to be on for say 6 hours a day--this will drain the batteries very quickly.

I need a lower power alternative (in 10s of uA to be constantly drawn instead of 15ma) for this to work, is that possible? Or am I better off just splitting the lamp wires and tying the first two to an ac adapter for the mcu/moc3010 and the second two to the light bulb-triac part?


  • \$\begingroup\$ Have you considered a latching relay? It will take more current than the optocoupler while switching, but no current at all until you need to switch back. \$\endgroup\$ Commented Sep 4, 2013 at 19:12
  • \$\begingroup\$ @AnindoGhosh Ah, I was looking into relays but I didn't realize a latching one wouldn't need a constant current draw. Do you have any recommendations for a model that can handle a 100W lightbulb, 120VAC outlet \$\endgroup\$ Commented Sep 4, 2013 at 19:16
  • \$\begingroup\$ Since you have AC available, it seems silly to me to use batteries to power the controller - use an AC adaptor. \$\endgroup\$ Commented Sep 4, 2013 at 19:17
  • \$\begingroup\$ @user2665581 See this relay for example. The key reason for using mechanical latching relays is that they will indefinitely hold position without any power consumption, after the set or reset pulse switches them. \$\endgroup\$ Commented Sep 4, 2013 at 19:20
  • \$\begingroup\$ @AnindoGhosh I'll need something smaller and under $10...not sure this solution will work for me \$\endgroup\$ Commented Sep 4, 2013 at 22:03

1 Answer 1


As mentioned in the comments, a latching relay would be an excellent choice: http://www.digikey.com/product-detail/en/kemet/EC2-12TNU/399-11031-5-ND/4291097


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