R2R ladder connects multiple buttons to one ADC pin

r2r-connects-multiple-buttons

If you've run out of I/O pins on a project and need a way to add user input you can find a slew of port expanders that work with various communications protocols like I2C and 1-Wire. But if you just want to add in some buttons without reaching for an extra IC you'll love this hack. [John Boxall] shows how to add four buttons using one ADC pin. The concept is nothing new. The buttons make up an … [Read more...]

Your first Digital to Analog Converter build

building-your-first-DAC

Have you ever built a Digital to Analog Converter before? This is a circuit that can take the 0 or 5V coming off of several digital logic pins, combine them together, and spit out one analog voltage that represents that value. If you've never made one, here's your chance. [Collin Cunningham] over at Make put together another lab video about DACs which we've embedded after the break. The circuit … [Read more...]

Resistive ladder volume control

preamp

[jefffolly] published some straight forward plans for a passive volume control. It uses a resistive ladder built across the contacts of 12W rotary switches. Each resistor provides a 5dB difference, and he recommends using 0.1% tolerance resistors to maintain accuracy. The use of discrete resistors instead of volume pots means that the output is much more predictable. All of the RCA sockets were … [Read more...]