Constructing a custom fitness tracker or gesture recognition device requires an accelerometer, specifically the ADXL335. This compact sensor detects acceleration through a suspended mass that shifts during movement. The setup involves connecting capacitors and operational amplifiers to process the sensor's output. The article outlines the steps to create a step counter by filtering and amplifying the signal, resulting in clock pulses for counting. A video demonstration showcases the circuit in action.
Create a touch sensor-controlled LED lamp with dimming and rechargeable features. This guide provides step-by-step instructions for building it yourself, using easily accessible components.
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.
