Good day guys. We have constructed a project called sound to light modulator but we don't know how the circuit really works, because we haven't taken a deeper course into circuit analysis. We don't know anything about triacs and optocouplers. Could you please explain to me in detail how this circuit works. Any help will be very much appreciated. Thanks in advance.

This is the schematic:

 

The led in the opto triac IC1 conducts when voltage is applied, this fires the triac inside, which connects the terminals Mt1 and Mt2 together, these terminals are connected to the Main Q1 triac Mt2 and Gate, when these are connected together the triac conducts. The triac disconnects when the AC voltage goes to zero, ready for the next cycle, as they will conduct on both posative and negative cycles.




http://www.allaboutcircuits.com/vol_3/chpt_7/6.html

 

Good day guys. We have constructed a project called sound to light modulator but we don't know how the circuit really works, because we haven't taken a deeper course into circuit analysis. We don't know anything about triacs and optocouplers. Could you please explain to me in detail how this circuit works. Any help will be very much appreciated. Thanks in advance.

You must not have gotten the instruction sheet with Kit 12 from Kits R Us. Here's their explanation of how it works.

The audio signal is applied
across the LED of the opto-triac. The
potentiometer adjusts the input sensitivity
while R2 limits the LED current. The LED
emits infrared light in response to the input
signal. The triac driver inside the MOC3021
package is sensitive to the IR light, and
activates a slave triac which controls the load.
R3 limits the gate current of the power triac
Q1.
A triac is a bilateral switch, similar to an SCR,
but conducts in both directions. Current flow
between the two main terminals is controlled
by the gate, and the series voltage drop is low
when turned on. The mains voltage applied to
X2 is thus fed to the lamp at X3 when the input
signal is large enough for the triacs to conduct,
and switched off when the signal level drops
and the triacs turn off. The triacs will turn on
for each half cycle of mains frequency that
their gates are triggered. The lamp is therefore
turned on and off very rapidly, depending on
the music level. Because of the thermal lag in
the lamps themselves, this appears as a
pulsating change in light intensity rather than
an on/off strobe effect.

 

Thank you very much!