Built-in project · no microcontroller

What is this part?

Two component testers with unknown parts in the sockets: one names a transistor and finds its base, collector and emitter, the other tells an LED from a diode. There is no microcontroller in it: the simulator solves the 4 parts as a circuit, so it runs the moment you press Run, and nothing needs compiling.

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What is this part?live0.000 s 0.00x
Click to open it in the editor
The circuit itself, running here on the simulator. Press what can be pressed; click anything else to open it in the editor.

How it works

There is no microcontroller in this one, so nothing is compiled: the simulator solves the circuit itself. The file in the editor is the notes that come with it.

sketch.ino
// What is this part, and which leg is which?
//
// Two testers, two unknowns. Each one drives its own sockets in twenty-four
// phases over about a tenth of a second, and names what the currents and
// voltages it got back can only be.
//
//   the left one   a small-signal NPN with its legs in 1, 2 and 3. The screen
//                  says NPN, the gain it measured, the base-emitter drop at
//                  the current it measured it at, and (the reading you
//                  actually wanted) which socket the base, the collector and
//                  the emitter are in. A transistor's legs are not marked.
//   the right one  a red LED. LED rather than DIODE, because it drops far more
//                  than a silicon junction does, and the anode is named.
//
// Drag anything else across a tester's sockets and it will have a go: a
// resistor (value, and which two sockets), a capacitor from about 0.1 uF up, a
// diode, a p-channel or n-channel MOSFET. Turn a part round in the sockets and
// the answer follows it round.
//
// What it cannot do, said plainly:
//
//   One part at a time. Two parts across the sockets at once is one thing it
//   cannot name, and it says so rather than guessing.
//   No inductors: measuring one needs an AC source this does not have.
//   No MOSFET threshold voltage: the gate is driven to one level rather than
//   swept, so what comes back is the on-resistance at 5 V on the gate.
//   No Zener voltage: it tests at 5 V and most Zener knees are above that, so
//   a Zener reads as an ordinary diode.
//   Capacitors under 0.1 uF go to the multimeter's capacitance range instead,
//   which reaches down to a nanofarad.
//
// And the honest caveat: the parts it is measuring are Mokxi's model cards, so
// the gain it reads is the beta the card was given, seen through one operating
// point. A real tester on a real transistor measures a device that is warmer
// than its datasheet and disagrees with the next one out of the reel.

Parts list

5 parts, plus the jumper wires. Every one is in the editor's parts bin.

How it is wired

5 connections, pin by pin, read from the circuit itself. Each line is one set of pins joined together, by a jumper wire or a breadboard strip.

  • Transistor (NPN or PNP) pin C; Component tester (1) pin 1
  • Transistor (NPN or PNP) pin B; Component tester (1) pin 2
  • Transistor (NPN or PNP) pin E; Component tester (1) pin 3
  • LED, red pin A; Component tester (2) pin 1
  • LED, red pin C; Component tester (2) pin 2

Change it and keep it

Open it in the editor, change the circuit or the code, and keep your version in a free account.