MIDI is normally baked into the chipset of a synthesizer, or something you use a microcontroller to handle. But that’s not the only way to speak the language! [Kevin] decided to have some fun doing ...

The circuit shown here can be used to convert a digital input signal having any desired duty cycle into a output signal having a duty cycle that can be adjusted between 10% and 80% in steps of 10%.

The circuit in this Design Idea makes a voltmeter that reads to 0.99V. The idea uses a counter IC to drive two sets of four LEDs (Figure 1). Each of these two sets represents a BCD ...