00:00UTC. Growing. And researching.
00:18Hello, how are you? Today I will be presenting the topic of power electronics, specifically how to create a dimmer.
00:25and the application of the UJT transistor as a pulse generator, and the ICL8038 oscillator that provides low distortion signals.
00:36Okay, for the first circuit it's the UJT transistor, as a sawtooth pulse generator,
00:42These pulses are very important for controlling the firing of an SCR and TRIAL.
00:51Its operation is as follows: when a direct current voltage is applied,
00:56to the RC series circuit, formed by the resistance of a potentiometer and the capacitor,
01:02This begins to charge, as this capacitor is attached to the emitter,
01:06When an intrinsic voltage is exceeded, the UJT will enter conduction, due to the unique resistance value.
01:12and the capacitor will begin to discharge rapidly at the UJT terminal and a voltage pulse will appear,
01:19by decreasing the capacitor's discharge current on the UJT's emitter,
01:23This starts a new charge and discharge cycle, and thus a pulsating signal appears.
01:29in the shape of a sawtooth, which can be used to control the firing of an SCR.
01:46The next circuit is about the operation of a DINER, for lighting three lamps.
01:56What are DIACs and TRIACs? Well, DIACS are a dual-connection semiconductor device,
02:02DIACS is a designation for THYRISTOR, and is normally used to auto-complete the varied firing rate of a
02:09TRIAC,
02:09A TRIAC, or TRIODE for alternating current, is a semiconductor device, from the THYRIST family.
02:21To turn on the lamps and control the lighting,
02:25I begin by explaining that with the TRIAC I obtain control of the complete alternating current cycle,
02:30We achieve TRIAC control with the DIAC; the DIAC priming cycles are controlled by the load.
02:36from the capacitor through the potentiometer,
02:39The remaining components serve to improve the circuit's presentation.
02:43For example, resistor R2 prevents excessively low effects when adjusting the potentiometer.
03:06The following circuit is now based on the pulse generator, ICL 8038,
03:11that a small amount of resistive and capacitive components can be added to the chip,
03:16It can produce sinusoidal, triangular, and rectangular waves.
03:19and the signal frequency, duty cycle, of adjustable distortion sinusoidal waves.
03:28The ICL 8038 is a monolithic integrated circuit capable of producing highly accurate sinusoidal signals,
03:34triangular and square waves, as well as pulses of variable width with a minimum of external components.
03:41The oscillation frequency
03:47It can be externally selected from 0.001 Hz to over 300 kHz
03:53using suitable resistors and capacitors with the possibility of frequency modulation
03:59and sweeping this with an external control voltage.
04:06Don't forget to subscribe, see you next time!
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