7) You are given the unknown transistor shown in the figure 7 and you use an ohm

Question

7) You are given the unknown transistor shown in the figure 7 and you use an ohmmeter to take resistance measurements as tabulated. The ohmmeter has two terminals: the positive (+) and the negative (-) as shown in tablel Table 1 Pins 1 & 2 Pin l (+) Pin 2 (-) 0.233 K2 | Pin 2 (+) Pin 3 (-) oo Pin 2 (+) Pin 1 (-100 Table 2 Pins 1 & 2 Pin 1 (+) Pin 2 Pin 2 (+) Pin 1 (-) 0.321k2 Pin 3 (+)Pin 2 (-) coPin 3 (+) Pin 1 (-) 0.259 k2 Pins 1 & 3 Pin 1 (+) Pin 3 (-) ? Pins 2 & 3 Pin 3 (+)Pin 2 (-) 0.259 K2 | Pin 3 (+) Pin 1 (-) ? Pins 2 & 3 2 Pins 1 & 3 Pin 2 (+) Pin 3 (-) oo Pin 1 (+) Pin 3 (-) oo Figure 7 a) b) What type of transistor were you given:- pnp or npn? What are the pin designations - collector, base, emitter? Give full explanations for your answers. Repeat for the data in Table 2

Explanation / Answer

Table 1

When Pin 1 (+) Pin 2(-) = 0.233 ohm means forward biased junction as resistance is low.

When Pin 2 (+) Pin 1 (-) = infinity means reverse biased junction as resistance is infinite.

Due to above two observation,  Pin 1 is P-type and Pin 2 is N type Junction terminals.

Again, When Pin 2 (+) Pin 3 (-) = infinity means reverse biased junction as resistance is infinite, and

When Pin 3 (+) Pin 2 (-) = 0.259 ohm means forward biased junction as resistance is low.

Due to above two observation,  Pin 2 is N-type and Pin 3 is P type Junction terminals.

Again, When Pin 1 (+) Pin3 (-) or Pin 1 (-) Pin3 (+) keeps the reverse biased state.

Hence its a PNP transistor.

Since Emitter is heavily doped compared to other two regions. Hence more charge carriers from emitter to base will cause low resistance between EB junction compared to CB junction.

Pin 1 (+) Pin 2(-) = 0.233 ohm is less than Pin 3 (+) Pin 2 (-) = 0.259 ohm. Hence Pin 1 is Emitter, Pin 2 is Base and Pin 3 is Collector.

---------------------------------------------------------------------------------------------------------------------------------------------------------

Table 2

When Pin 1 (+) Pin 2(-) = infinity means reverse biased junction as resistance is infinite.

When Pin 2 (+) Pin 1 (-) = 0.321kohm means forward biased junction as resistance is finite (LOW).

Due to above two observation,  Pin 1 is N-type and Pin 2 is P-type Junction terminals.

Again, When Pin 2 (+) Pin 3 (-) = infinity means reverse biased junction as resistance is infinite, and

When Pin 3 (+) Pin 2 (-) = infinite ohm means reverse biased junction as resistance is infinite.

Due to above two observation,  Pin 2 is P-type as well as Pin 3 is P type Junction terminals.

Again, When Pin 1 (+) Pin3 (-) infinite ohm means reverse biased junction as resistance is infinite and

Pin 1 (-) Pin3 (+) = 0.259 k ohm means forward biased junction as resistance is finite (LOW).

Hence Pin 1 is N-type whereas Pin2 and 3 are P type. So, its a PNP transistor.

Since Emitter is heavily doped compared to other two regions. Hence more charge carriers from emitter to base will cause low resistance between EB junction compared to CB junction.

Pin 2 (+) Pin 1(-) = 0.321k ohm is more than Pin 3 (+) Pin 1 (-) = 0.259 kohm. Hence Pin 1 is Base, Pin 2 is Collector and Pin 3 is Emitter.

Related Questions

Navigate

• Browse (All)
• Browse 7
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.