Let's assemble a completely analog PWM LED brightness controller using four operational amplifiers and figure out why PWM is needed and what it is.
Using a 74LS90 and resistor DAC, the circuit outputs stepped voltages for LED brightness. An op amp amplifies them, providing incremental LED current. Simple dividers and counters manage timing, while a flip-flop and 555 monostable enable manual or automatic stepping. This low-cost approach demonstrates basic LED dimming with minimal components.
With Fresnel lenses focusing heat (IR) onto pyroelectric sensors, PIR sensors detect motion from changes in IR distribution. Two amplification stages and a window comparator boost signals, triggering a relay output. Chips like BISS0001 unify these elements, adding adjustable timing and re-trigger controls for seamless motion-detection functionality.
DC PLC protocols monitor solar panels and control motors. G3-PLC, PLC-Lite, and IEEE 2847-2021 are key protocols. Specialized chipsets are cost-effective, except for IEEE 2847-2021, which uses software.
PLC transmits data over power lines, using high frequencies for dual power and data transmission. Applications include smart meters, street lighting, and home automation, with speeds up to a few Mbps over 6 miles.
