Ang diode, mula sa loob The diode, from the inside — why it only lets current through one way

1. Isang direksyon lang One way only

Parang balbula ng tubig ang diode: bumubukas sa isang direksyon, sumasara sa kabila. A diode is like a one-way water valve. Anode (+) on the plain end, cathode (−) on the stripe end.

2. Conductor, insulator, semiconductor

Sa tanso, malayang gumagalaw ang electron. Sa goma, hindi. Sa silicon, kaya nila kung bibigyan ng kaunting enerhiya. Copper: electrons move freely. Rubber: they can't. Silicon: they can, given a little energy (heat, light).

3. Doping

N-type: phosphorus (5 electrons) → sobrang electron. P-type: boron (3 electrons) → may butas (hole). N-type has spare electrons; P-type has holes where an electron is missing.

4. Ang PN junction

Sa gitna, may depletion region na parang pader, mga 0.7 V. Kailangang lampasan ang 0.7 V bago dumaloy ang kuryente. Kapag baliktad, lumalaki ang pader. The depletion region is a ~0.7 V wall. Forward voltage above 0.7 V pushes through it; reverse voltage makes it wider.

5. Saan ginagamit Where it's used

Proteksyon kung baliktad ang baterya; at gawing DC ang AC (rectifier). Reverse-battery protection; turning AC into DC: half-wave (1 diode), full-wave (4 diodes), smoothed with a capacitor.

6. Subukan Test it

Diode mode: pula sa anode, itim sa guhit → ~0.5–0.7 V. Baliktarin → O.L. Kung may basa sa dalawang direksyon, sira. Red on anode, black on the stripe: ~0.5–0.7 V. Swap: O.L. A reading both ways means it's broken.