ac light dimmer light using triac and triac

[dumi]

Its ohk,I am using LM358

- - - Updated - - -

Don't u think that I should change the capacitor?

 

[KerimF]

Its ohk,I am using LM358

It is equivalent to LM324! And you mean you are using 2 ICs since the circuit needs 3 opamps.

Now, let us simplify our tests to find out how or why the output refuses to be as expected

Please note that the following tests don't need all the elements after the end opamp output.
For clarity, I will refer to the circuit I attached on post #35 only, ok?

 

[dumi]

U referring to the test we use 2 test yesterday?

 

[KerimF]

U referring to the test we use 2 test yesterday?

No, I mean new tests since we are sure that the MOC and the power triac are fine.

Added:
As I said, I will take the lables and names from the circuit shown on post #35 only to avoid ambiguity.

Added:
from post #82

Please note that the following tests don't need all the elements after the end opamp output.

First, connect a 10K from Vcc to TRG (o/p of U3). I assumed, as I mentioned earlier, you already removed R13, the red LED, MOC... etc.

 

[dumi]

Ohk,so we must do another test?

 

[KerimF]

Yes

Looking at the traces (always post #35), we see V(pls) as narrow positive pulses. Therefore the voltage at "PLS" (o/p of U1) should be rather low though not zero.

Also we see a ramp (from high to low) at Vo; o/p of U2, trace of V(vo). Therefore, the DC voltage at Vo should be close to Vcc/2 (close to 6V if Vcc=12V).

Try to measure these two nodes since they are not affected by the potentiometer U4 (10K).

 

[dumi]

Yes,I did.

- - - Updated - - -

U4 I get 10.25V

- - - Updated - - -

U4 I get 10.25V

- - - Updated - - -

U mean the the two node of U4?

 

[KerimF]

Are we looking at the same circuit?

I meant by the two nodes:

(1) the node PLS, the o/p of U1

(2) the node Vo, the o/p of U2

 

[dumi]

(1) 13.89v
(2)0v

 

[KerimF]

As you see, both voltages are too far from what they should be
(1) low voltage close to 0V (around 0.5 V).
(2) Vcc/2, so if Vcc = 12V, it is around 6V.

Are you sure, your circuit is connected exactly as the one on post #35?

Added:
Since you use LM7812, your Vcc should be 12V. The output of LM7812 could be lower than 12V if its input voltage goes below 13.5V (this happens when the mains voltage is relatively low). But Vcc doesn't increase above 12V (as you said once, to 15V) no matter how high the mains voltage is (though the IC, LM7812, may get very hot). Your Vcc=15V of yesterday made me confused

 

[dumi]

Yes,U know why I am saying this?its because when I do the test at school lab I get the same waves as you get earlier.

 

[KerimF]

U know why I am saying this?

We say, you and I, a lot of things. What do you mean by 'this'

 

[dumi]

Sorry miss test,I'm was trying to say when I was doing the test in the lab I get the same waves as u did,

- - - Updated - - -

may be my regulator (LM7812) is faulty or maybe is not connected properly

 

[KerimF]

For LM7812:
pin 1 is input
pin 2 is ground (connected to case)
pin 3 is output

We can see pin 1 at the left if the plastic side of the package is in front of us and the 3 legs are down.

- - - Updated - - -

So what can we do?
The circuit is rather simple. But it seems one component or more are faulty now

Added:
For instance, do you know the pins of LM358?
pin 1 : o/p A
pin 2 : IN- A
pin 3 : IN+ A
pin 4 : Ground
pin 5 : IN+ B
pin 6 : IN- B
pin 7 : o/p B
pin 8 : Vcc

 

[dumi]

I suspect that something is not right, but what confuses me is that all three circuit works the same I think it could be over voltage that a may damage the components.When you do measurement to your circuit do you get the same values that I get?

 

[KerimF]

Sorry, I was taking my dinner
To be honest, for such a simple circuit, there is no need to build it just to verify that it runs properly. In this case a simulator is more than enough

But on your side, since you cannot check visually, using a scope, the voltages at every node on your real circuit to find out the cause of the failure, it may be very hard to be 100% sure of anything. Also the probes of a scope have usually 10M ohm as internal impedance while many multimeters loads the circuit with 1M only (do you know it of yours) and this may alter the voltages on some high impedance nodes on the circuit (mainly at the input pins of an opamp).

Could you have a good LM7812?
Did you measure its input DC voltage?
Is the ripple voltage on C1 (100uF) rather high? (you can measure it with the AC voltage tester).

In case your circuit is on a breadboard, is it difficult for you taking an image of it? Perhaps I can help you localise where it seems there might be something wrong.

As a first step, we should focus on U1 and let its ouput generate narrow positive pulses. As we know, in this case, its output voltage should be low (around 0.5 V).

 

[dumi]

i will check my transformer because when I test the voltage on my bridge is not giving me 12V

- - - Updated - - -

I will do.

 

[KerimF]

For instance, we may let the circuit work on 5V only. Do you have LM7805? In this case, you just need a voltage higher than 7V at the input of the regulator.

- - - Updated - - -

The following circuit works on 5V (with LM7805).
https://obrazki.elektroda.pl/6981210000_1382124616.png

 

[dumi]

Yes,I have LM 7805

 

[KerimF]

For instance, the page of the "Manage Attachments" doesn't open since yesterday. Is it just me? My internet browser is IE9.