The current limit

// The current limit, and what CV and CC mean.
//
// The supply is set to 12 V with the current knob at 1.00 A, and there are
// ten ohms across it. Ohm's law wants
//
//   I = 12 V / 10 ohm = 1.2 A
//
// and the supply is not allowed to give that. So it does the other thing it
// can do: it holds 1.00 A and lets the voltage fall to whatever ten ohms
// makes of it.
//
//   V = 1.00 A x 10 ohm = 10.0 V
//
// Which is what both displays say, and what the multimeter across the load
// says as well. The CC lamp is lit, not CV, and that is the whole reading:
// the supply is in constant current, so the number you set on the voltage
// knob is not what is on the terminals.
//
// Things to try, all of them with the circuit still running:
//
//   CURRENT +   turn the limit up past 1.2 A and the lamp flips to CV, the
//               voltage climbs to the 12 V you asked for and the current
//               settles where Ohm's law puts it. The crossover is the thing
//               to watch: it happens at exactly 1.2 A.
//   CURRENT -   turn it down to 0.50 A and the output halves to 5 V. In
//               constant current the supply IS the resistor.
//   OUTPUT      takes the terminals off the circuit. The meter reads zero,
//               which is different from the supply reading zero.
//
// Why this matters: a current limit is what lets you power something you are
// not sure about. Set the limit to what the circuit should draw, and a short
// or a part in backwards costs you a lamp on the front panel instead of a
// part. It is the single most useful thing on a bench supply and the one
// beginners leave wound up to maximum.