Help for the project Dark activated lamp

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It's a multivibrator, like an oscillator. It applies pulses to the gate of the SCR to turn it on. When light shines on the photocell it shorts C1 which stops the oscillation and turns off the SCR.
 
Thanx... but, will you explain the circuit from the plug going to the parts?? Can you please??
 
mamand said:
Thanx... but, will you explain the circuit from the plug going to the parts?? Can you please??
Click to expand...
hi,
Its not a multi vibrator.
.
Transistors Q1 and Q2 act as voltage controlled switch, similar to a Uni junction.

On every half wave rectified cycle, cap C1 charges via R2, when the charge on C1 exceeds the threshold breakdown voltage of the transistor switch the triac gate is pulsed as C1 is discharged via Q1 and Q2 across R7.

NOTE: the triac trigger pulse occurs some time after the zero crossing point, which means the lamp will not be at its maximum intensity. It will also radiate a 'buzz' sound and interference.

When light, the LDR resistance is low enough to hold C1 below the transistor switch threshold voltage.

The gate of the triac should have a 47R is series from R6 and R7 junction.
 
ow... is that so?? sad,. . do you have some ideas to solve that flickering? is the circuit ok about that flickering?? i guess the amp will rise if that happens a long time doesn't it??.

and hey,, i ordered the capacitor and i dont have it yet..

I plan to test the circuit without the capacitor..
What will happen by then?
 
I already tested my circuit but the r7 was damaged (burned).. What would be the possible cause?
 
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mamand said:
I already tested my circuit but the r7 was damaged (burned).. What would be the possible cause?
Click to expand...

hi,
Assuming that you have built the circuit as shown in the diagram, I would check the connections to the SCR's GATE pins, ensure that you have wired the SCR correctly.

Which SCR type are you using.???

edit:
corrected SCR

T106D image
 

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R7 will burn when the full wave bridge rectifier or the SCR have the pins connected backwards.
 
Its C106d.

Assuming that the pins of the SCR were wrongly connected, i think the first one that will burn is the SCR...?

What I did is I change the 470 ohms 1/4W into 470 ohms 1/2W..
I tested it again and the r7 didn't burned.

My problem now is the lamp will not turned off even if there's sunlights..
I already tested my LDR and its still functional..

)..
Any idea's guyz?
 
mamand said:
okie... ahmmm. where is that 0V?
Click to expand...

The '0V' line is the negative output of the bridge rectifier or the Cathode of the SCR.

As your knowledge of electronics seems limited, I would advise caution when working on mains powered, non transformer isolated projects, they can be lethal.
 
thx for the concern.. Yah i dont have much knowledge in electronics... but i have some in electrical.. ^_^.

since my r7 was blown, isn't it possible to judge that the transistor was reason for the "cannot be turn off problem".. ??
what if the transistors are also affected due to the damage of r7? I still have to test it....
 
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