Triac Output Flickering Problem

[Boncuk]

Hi saturn1bguy thanks for the reply.

I'm going to use 4.7K.

Guarantees a long life for the bulb.

 

[MrAl]

Hello,

The gate resistor is calculated from the power supply voltage minus
the gate forward voltage divided by the max gate current required for
proper operation.

For example, for this triac the max gate current is 10ma or 5ma if you
restrict the operation to certain quadrants. Lets say you want to go
with 10ma. Also, Vg max is 2v. This would mean
R=(V-Vg)/0.010
so with a power supply of 5 volts R would be:
R=(5-2)/0.010=300 ohms.
With a power supply of 10 volts,
R=(10-2)/0.010=800 ohms.

You can calculate the required resistance for any power supply voltage
this way.

 

[SMUGangsta]

I need to turn on the bulb for 30 mins & off.
......
I want to stop this flicker thing with least amount of parts.

What do you mean you nead the bulb to come on softly in the oiriginal post?

Cant you just use your logic to switch a relay on then off after 30mins

 

[Suraj143]

For example, for this triac the max gate current is 10ma or 5ma if you
restrict the operation to certain quadrants.

Hello MrAl your example gave a good understand.Thanks for that.

But I have to tell I'm new to TRIACs.I don't know what are quadrants.& how the triac operates.

 

[Suraj143]

What do you mean you nead the bulb to come on softly in the oiriginal post?

Cant you just use your logic to switch a relay on then off after 30mins

Hello I'm using transformer less power supply.It cannot supply too much current probably 30-40mA depends upon the capacitor.

 

[on1aag]

Hi Suraj143,

The quadrant thing is actually very simple.

When you operate a triac in the first quadrant the voltage
applied at the anode is positive with respect to the cathode
and the trigger current applied at the gate is also positive
with respect to the cathode.

Second quadrant: Anode voltage also positive but the gate
current is negative with respect to the cathode.

Third quadrant: Anode voltage is negative and gate current
is also negative with respect to the cathode.

Fourth quadrant: Anode voltage is also negative but the
gate current is positive.

You are using the first and fourth quadrants.
Look at the datasheet of the TIC206 at page 1 bottom right.

If you want to be sure that the triac will conduct you need
to apply the maximum gate current for certain triggering
for that that quadrant. (It has nothing to do with the
maximum gate current which is +/- 200 mA)
Therefore you need to apply minimum 10 mA gate current to
be sure that the triac will conduct at all angles.
(From 0 to 360 degrees of the applied sinewave to the anode)

on1aag.

 

[MrAl]

Hello MrAl your example gave a good understand.Thanks for that.

But I have to tell I'm new to TRIACs.I don't know what are quadrants.& how the triac operates.

Hello,


Well, you dont have to know what the quadrants are if you always
use 10ma for your triac. The triac you are using works in every
quadrant if you make sure you use at least 10ma gate current.
Use 10ma gate current and you're done.

Not all triacs work with that low gate current, but yours does.

If you would like to learn more about the quadrants anyway
that's up to you, but you can get this working without knowing
that information yet.

 

[Suraj143]

OK Thanks guys on1aag & MrAl that gave me a lot of understand of triacs.