Circuit Splash

Here is a simple audio amplifier circuit that is easy to build and has few components. This circuit is built around the LM386 (click for datasheet) audio amplifier integrated circuit, useful when you need to power medium sized speakers from a music player that can only drive earphones.

I find this almost therapeutic to watch, perhaps it's a little OCPD in me but seeing an Arduino Uno control a machine which will sort out your sweeties by colour is great. This little video does well to demonstrate it working with the 3D printed parts, an RGB and an infra-red sensor doing the work in tune with the motors.

Darkness detector is simply a LDR (Light Dependent Resistor) interfaced square wave generator. In this project the square wave generator is developed as a 555 Timer IC based ASTABLE MULTIVIBRATOR. Before going any further we must get the basic details on the LDR. The figure below shows an image of various types of LDR.

The basic circuit operates at a frequency determined by R1, R2 and C1 and has a pulse width range of 0 to 100 percent.

The following diagram shows a basic circuit with an open collector output that would require a pull up resistor at its output. The parts values are the nominal values of the components used.

Air-powered water rockets are easy to build and the fuel is free, but do you want to push the envelope? How about a two-stage water rocket? And instead of pressurized air, how about an explosive gas? I know the perfect gas to use.