Lithium Battery Protection for Small Projects

Lithium cells haven’t become the predominant power source for mobile electronics without reason. Circuits for their—very necessary—protection are naturally plentiful as well.

One particular weak point of many protection schemes, however, is deep discharge protection. Common practice is to discharge LiPo/LiIon cells no further than 3 V to not risk permanent damage. Yet, most protection ICs cut off only at 2.5 V, and you thus have to rely on additional battery voltage monitoring.

Es ist Mittwoch.

Sometimes blog posts just have to sit in the drafts for a while. This one had the opportunity to mature for about a year. The actual project lies back about two and half years by now. The pictures I have of it haven’t got any better in the meantime, so I might just as well hit ‘post’ on this split-flap calendar I built for a friend.

Most of the time, it doesn’t do much. Once a day, it advances by one flap and ⅐ of the time, it announces the day of the week, Wednesday.

Zoom H4n Pro Repair

A Zoom H4n Pro audio recorder found its way to me, non-working. Recordings seemed to be silent, but with loud enough input you could just make out some distorted sound in the recording. After (unneccessarily) disassembling it completely, I found out that the power supply of the preamplifier board was sitting at around 0.8 V, which thankfully/boringly turned out to be the only fault in the unit.