Skip to content

2026

  • 7 min read

Lab note: CMOS analog switch non linearity

CMOS analog switches are a very convenient way to pass signals around: they work up to MHz frequencies, they don't statically consume power and their two terminals can float arbitrarily between the rails. Their downsides are their badly characterized ON resistance, and the fact that it varies with applied voltage...

This has made them shunned in some audio circles, because this brings distortion. But I grabbed a whole bag of DG212CJ quad analog switches at 39C3, and it'd be a shame not to use them.

  • 9 min read

Caring for and designing with audio jacks

Audio jacks are... a mess. There are at least 4 different sizes, of which 2 are common, that are called by different names across the Atlantic. There's a variable number of contacts and at least two different schemes for using them. Originally designed for telephone exchanges, they're now used for general consumer audio as well as professional recording equipment. Some are even used for power, for connecting guitar pedals... The "jack connector" may as well be more of an idea than an actual standard.

Nonetheless, in the consumer space, today, there are de facto standard uses for jack connectors. Here, I try to provide an overview of what to expect when tinkering.