Solid-state-light-dissolver

Description: The dimming action is controlled by varying the amount of current passed through triac Q4, which in turn regulates the lamp connected to the AC receptacle. The unijunction transistor Q3 functions as a relaxation oscillator, with its output pulse frequency determined by the rate at which capacitor C2 recharges after firing. Transistors Q1 and Q2 provide the charging current, while the time-constant networks formed by R3/C1 and R1/R2/C1 dictate the turn-on and turn-off times. Inside IC1, there is an LED, a detector, and a small triac. In operation, the low-level pulses generated by Q3 cause the LED in IC1 to emit brief bursts of light, which are detected and converted into electrical current pulses by the internal detector. This small current triggers the internal triac, which then sends pulses to the gate of power triac Q4, activating it to supply current to the lamp. Potentiometer R4 acts as the master control for the pulse rate, allowing for manual adjustment and setting a limit on the brightness of the lamp connected to the AC receptacle. Momentarily pressing switch S2 results in the instant activation of the lamp. Choke L1 is employed to suppress any voltage spikes generated by the power triac, thereby reducing interference with AM radio reception. No additional measures are necessary to mitigate interference for FM and TV reception, as these media are generally resistant to this type of noise.

The circuit operates on a principle of phase control dimming, where the triac Q4 modulates the power delivered to the load (lamp) by adjusting the conduction angle. The unijunction transistor Q3, acting as a relaxation oscillator, plays a crucial role in generating the timing pulses necessary for controlling the gate of triac Q4. The capacitor C2's charge and discharge cycles determine the timing of these pulses, hence influencing the brightness of the lamp. The arrangement of resistors and capacitors (R3/C1 and R1/R2/C1) is critical for establishing the desired time constants that dictate how quickly the circuit can respond to changes in input conditions.

IC1 contains essential components that facilitate the conversion of optical signals from the LED to electrical signals, thereby creating a feedback loop that enhances the stability and responsiveness of the dimming circuit. The LED's brief illumination serves as an indicator and a trigger mechanism for the internal triac, ensuring that the power triac Q4 receives timely and precise gating signals.

The use of potentiometer R4 provides flexibility in adjusting the dimming level, allowing users to set their preferred brightness while ensuring that the lamp does not exceed safe operational limits. The momentary switch S2 offers a convenient way to bypass the dimming control, providing instant lamp activation when needed.

To maintain the integrity of the circuit and minimize electromagnetic interference, choke L1 is strategically placed to filter out high-frequency spikes that could affect nearby radio equipment. This design consideration is particularly relevant for AM radio, while FM and television signals remain unaffected due to their inherent resistance to such noise. Overall, this circuit exemplifies a well-engineered solution for controlling lamp brightness with precision and reliability.The dimming action is controlled by varying the amount of current passed through triac Q4 and, thus, the lamp plugged into ac receptacle SOL Unijunction transistor Q3 operates as a relaxation oscillator whose output pulse frequency depends on how fast capacitor C2 recharges after firing. Transistors Ql and Q2 furnish the charging current, with the R3/Cl and Rl/R2/Cl time-constant networks controlling the turn-on and turn-off times.

Inside ICl is a LED, a detector, and a small triac. In circuit, the low-level pulses coming from Q3 make the LED in ICl emit short bursts of light that are picked up and converted into electrical current pulses by the internal detector. This small current triggers the internal triac, which then outputs the pulses to the gate of power triac Q4, triggering it on so that it delivers current to the lamp. Potentiometer R4 serves as a master control of the pulse rate and provides both manual control and a limit in the brightness of the lamp plugged into SOL Momentarily pressing S2 causes the lamp to instantly turn on.

Choke Ll suppresses any spikes produced by the power triac and limits interference with AM radio reception. No safeguards against interference need to be made for FM and TV reception, since these media are immune to this type of noise.