How do I choose a good transistor?

In choosing a suitable switching transistor:

1. The transistor’s maximum collector current must be greater than the load current.
2. The transistor’s maximum current gain must be at least 5 times the load current divided by the maximum output current from the IC.

What is an ideal transistor?

An ideal transistor switch would have infinite circuit resistance between the Collector and Emitter when turned “fully-OFF” resulting in zero current flowing through it and zero resistance between the Collector and Emitter when turned “fully-ON”, resulting in maximum current flow.

What are the important transistor ratings?

The rating for maximum collector-emitter voltage VCE can be thought of as the maximum voltage it can withstand while in cutoff mode (no base current). This rating is of particular importance when using a bipolar transistor as a switch. A typical value for a small signal transistor is 60 to 80 V.

What parameters are important for transistor model?

The important parameters of a transistor are the same as those for any amplifier, namely, input and output impedances, gain and feedback ratios. The amplifier characteristics will, of course, be determined by the parameters of the active devices it contains.

Which transistor is mostly used?

The MOSFET is by far the most widely used transistor for both digital circuits as well as analog circuits, accounting for 99.9\% of all transistors in the world. The bipolar junction transistor (BJT) was previously the most commonly used transistor during the 1950s to 1960s.

What are the factors to consider in substituting the transistor?

Depending on the application and type of the original transistor, the basic areas of concern are the voltage, power, current, switching speed and amplification characteristics of the substitute. Other areas that may also be important include the lead locations on the transistors and the mounting options.

How do you find a transistor?

Connect the positive lead of the multimeter to the Base (B) of the transistor and connect the negative lead to the Emitter (E) of the transistor. If it is an NPN transistor then meter should show a voltage drop between 0.45V and 0.9V. If it is a PNP transistor, then it should display see “OL” (Over Limit).

Which transistor is more stable?

In particular, the stability factor, which is a measure of the change in collector current with changes in reverse saturation current, is approximately β+1. To ensure absolute stability of the amplifier, a stability factor of less than 25 is preferred, and so small-signal transistors have large stability factors.