Ugly Face on OSH Park

Just published the Ugly Face v 1.1 to OSH Park. Built and tested, it works well! This is classic DIY project, it’s almost a rite of passage for new DIY stomp box enthusiasts.

The Ugly Face is more of a synthesizer than fuzz pedal. It produces square output from the input guitar signal. You can imagine the internal oscillator running whenever the input signal reaches a threshold. This gives you frequencies above or below the input frequency at the output. The Ugly Face also adds an envelope control to animate the oscillator frequency. The sound is surprisingly more musical than a lot of other “harsh” distortions.

Order some boards at OSH Park and follow the build docs below to make your own.

LM386 Gain

I’ve playing around with the 386 Audio Amplifier. This is a really great chip. It has a lot of possibilities. Looking at all of the great circuits that use this I’ve noticed there are many different ways to set the gain.

Gain is set using pins 1 and 8. With these two pins open the Gain is 20. Connecting these pins, in any of the various ways, you get gains from 20 to 200. Or at least this what I think from reading the datasheet.

The image below shows 6 different methods I have encountered for setting the gain. The datasheet suggests method 2. Many projects use method 3. The datasheet suggests using method 2 and attenuating the input to create variable gain. Which I haven’t shown here.