R/2R ladder DAC

This is a famous digital to analog converter that uses a resistor ladder network in order to convert the signal from digital to analog. It has 8bit resolution, but you can easily increase it, if you follow the pattern. The circuit is very reliable and it doesn't require a lot of time to build it.

Serial ADC for BS2

Connect National's Semiconductors serial analog to digital converter ADC0831 to Basic Stamp 2 and digitize your analog data. The required program couldn't be simpler (literally only 3 commands).

Voltage to current converter (V-I converter)

This circuit is one of the simplest voltage to current converters to drive low loads. In this example a small 0,25 Watts speaker, with 8Ω resistance, is driven. It is suitable for microcontroller designs or any other circuit that uses PWM (TTL logic). You can use it for analog signals as well.

Stereo amplifier with KIA6210AH

This is a HiFi stereo amplifier based on KIA6210AH dual audio power amplifier chip, with output power 2x22 Watts (this is the circuit's true output power and not the sound power. As you can see is fairly high). KIA6210AH chip is not hard to find. Personally, I dig it out from an old car cassette player.

A simple SI-Prog

With the following circuit you can easily program the AVR microcontrollers AT90S1200, AT90S2313 (or ATtiny2313), AT90S8515 and AT90S4414, using the freeware programmer PonyProg by Claudio Lanconelli. You can download the program for free from the author's website (www.lancos.com/prog.html).

Sound detection circuit with variable sensitivity

This is a simple circuit that can detect sounds by using a common condenser microphone. Sensitivity is variable . The circuit's output becomes High each time a sound is detected, otherwise it is in low level. You can use it in simple robots for sound responding (e.g. reaction -> when you clap your hands). This circuit recognize human voice as a common sound (you can't use it for voice recognition).