N8VEM single board Z80 computer

n8vem

The N8VEM is a homebrew computer project based on the classic Z80 microprocessor. It’s designed to be easy to build using large TTL DIP components instead of SMD devices. It runs the CP/M operating system and all drives are virtual in RAM/ROM. While the base hardware is interesting, we really like the potential for expansion using a backplane. Have a … Read the rest

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 … Read the rest

Wireless BlinkM control

blinkm

[John] has been working with several BlinkM RGB devices. He’s created a controller to talk to each of the BlinkMs wirelessly and change their behavior. The core is an old relay tester box used to test telephone circuits. Each of its four knobs are connected to the analog inputs on the Arduino. The signal is transmitted using RFlink devices. Each … Read the rest

DC gearmotor teardown

dcmotor

The RepRap project has made heavy use of the Solarbotics GM3 Gearmotor as part of their extruders. Unfortunately they’ve proven to be underpowered for the task and the plastic gears could cause future problems. [Zach] decided to investigate some other options. He bought a pile of motors from Kysan to try out. He posted a teardown of one of the Read the rest