Identify the type of base and tube

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Identify the type of base and tube

Use R*100 (or R*1K) file of ohm file, first connect one pin with red pen, black pin to another pin, measure two resistance values, then use red pen to connect another pin Repeat the above steps, and measure a set of resistance values, so that 3 times, one of the two resistance values is very small, corresponding to the red pen connected to the measured value is connected to the base, and the tube is PNP type On the contrary, if the black pen is used to connect a pin, the above method is repeated. If the two resistance values are small, the corresponding black pen is the base, and the tube is of the NPN type.

Discriminating collector

Since β is large when the emitter and collector of the triode are properly connected (the amplitude of the hand is large), β is much smaller when reversed. Therefore, first assume a collector, connected with ohms (for NPN-type tubes, the emitter is connected to the black test lead, and the collector is connected to the red test lead). During the measurement, the base and the hypothetical collector are pinched by hand, and the two poles cannot be contacted. If the pointer swings a large amplitude and the pointer swings small after the two poles are reversed, the assumption is correct, thereby determining the collector and the emitter.

Estimation of current amplification factor β

Use R*100 (or R*1K) file of ohmic file, connect the emitter of the NPN tube, the red pen to the emitter, and the black pen to the collector. When measuring, just hold the base and the collector by hand. ), and the handle is released in two cases, the size of the small pointer swing, the larger the swing, the higher the β value.