Electronics by the path, not by the result.
What people believed, what didn’t fit, the word that remains, and the formula after. At the bench, with a multimeter.
The paths
Three crossings, from one stop to the next. Start where you like, stop when you like.
From the sun to the wheel
The panel, the charger, the pack, the controller, the motor. Small electric traction, end to end.
The bare chip
The microcontroller without its board: the clock, sleep at a few microamps, the sensor, the bus, the program.
The complete device, the guitar amp
Reading a commercial schematic stage by stage, the power supply, the amplifier, feedback, troubleshooting.
Entries, for those who don’t want a path
Four kinds: a question, a story, an opened object, a bench experiment for tonight.
The EGO pack opened
Ten groups, the nickel strips, the BMS, and the protections you don’t see.
serves 6.2 · 1.1 storyElectricity before Franklin
Before it was something you measure, electricity was a parlour curiosity for two thousand years.
serves 1.1 storyThe Leyden jar
If electricity is a fluid, you ought to be able to bottle it.
serves 1.1 storyFranklin’s fluid
A multimeter in series shows a number with a sign, and the sign depends on which lead you put on which side.
serves 1.1 storyGalvani’s frog
The pack of a cordless drill shows 3.7 V cells.
serves 1.1 benchWhat the USB power bank really gives
A 10,000 mAh bank should fill a 4,000 mAh phone two and a half times; it does it twice, and the bank gets the blame.
serves 1.2 benchThe drop over ten metres
An AWG table says thirteen milliohms per metre for 16 gauge, and nobody believes it until they have seen it.
serves 1.3 benchTwo nails in a glass of water
We think water conducts.
serves 1.1 benchThe pencil lead and the lighter
We think heat gets in the way of everything that conducts: the hot contact resists more.
serves 1.1 benchThe battery in the freezer
We think the cold drains the battery: the flashlight dies in January and comes back to life in the house.
serves 1.1 questionWhy does a contact get hot?
The bike, after a climb: the pack cable is cool, but the XT60 that joins it to the controller is warm, its nylon browned on one side.
serves 1.1 questionThe "5 Ah" pack that doesn’t last
October, the woodpile to get done before the snow.
serves 1.2 questionWhy does a battery weaken in the cold?
January in New Brunswick, -20 °C.
serves 1.1