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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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.
// 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.
- 1 × Half breadboard
- 1 × Transistor (NPN or PNP)
- 1 × LED, red
- 2 × Component tester
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.