What Values Should I Use For This Small Circuit?

Discussion in 'The Projects Forum' started by K-Young, Oct 2, 2009.

  1. K-Young

    Thread Starter Member

    Aug 22, 2009
    27
    1
    Alright, here is what I want to do using a triac:

    http://sub.allaboutcircuits.com/images/03225.png

    The only thing is that I don't know what the values of my components should be, given the load I have to drive.

    My load it going to be heating elements from a toaster that I will pull out and this is what I would like to control. I've taken some measurements already, and the values for the heating element are as follows(I basically plugged the toaster in) on a 120V line:

    About 900W
    Current is about 8-9 Amps

    I have very little experience with DIACs and TRIACs, so any help would be appreciated.

    Thanks.
     
  2. lightingman

    Senior Member

    Apr 19, 2007
    374
    22
    Hi,

    This is the very least of components you can use for this application. There should be another fixed and pre-set resistor in series with the pot. The fixed resistor will limit the current and the pre-set to adjust the minimum level. There should also be a choke in series with the load and a capacitor in series with a 100 R resistor across the triac for RF suppression. The triac needs to be rated at twice the lamp current, the diac can be any one (BR100 is good). The capacitor should be around 0.47uF @ 200 volts (for 110 v mains) and 400 volts (for 230 v mains). The pot around 220 / 250 k, pre-set 47 k, fixed resistor 10k.

    BE CAREFUL IF YOU ARE EXPERIMENTING. HIGH VOLTAGE CAN KILL.....

    Hope this helps.

    Daniel.
     
  3. K-Young

    Thread Starter Member

    Aug 22, 2009
    27
    1
    Thanks for the help, and I'll try to be careful :D
     
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