problem with dimmer schematic

Hi,

I am trying to make one dimmer. I use a MOC3021 and a TIC 106D (5 amps). The main power supply is 220V. The lamp that i try to control is 500W. The problem is with the resistor for the gate of the triac.I Have attach the schematic. This is as the one of the datasheet of the MOC3021.

Every time, the 330ohm resistor is burned. I have tried another type of connection with a single resistor from the anode to pin 6 of the MOC, but the same thing happens. If i use a rather big resustor, like 220KOhm, it works for about one minute, and then the light is turned on at maximum power by itself.

Anyone any idea for the resistor burnong staff?

Hi,

A real quick look and it seems that you probably need a much lower value resistor there.
The large value makes the triac wait too long to turn on when the voltage is too high.
A much smaller resistor should do it.

MrAl said:

Hi,

A real quick look and it seems that you probably need a much lower value resistor there.
The large value makes the triac wait too long to turn on when the voltage is too high.
A much smaller resistor should do it.

Click to expand...

The problem with lower resistor is that within fractions of seconds it burns in fire and smoke... What do i do wrong?

pcbheaven.com said:

The problem with lower resistor is that within fractions of seconds it burns in fire and smoke... What do i do wrong?

Click to expand...

hi,
The MOC3081 is connected as per this diagram.

Hi again,


That schematic looks better already. I used these kinds of chips in the past and never used a capacitor like in the original circuit posted here.
Perhaps the cap is storing too much charge. The only other possibility is that something is not connected properly.