if it's known that a simple transistor circuit doesn't use the base then what purpose does it serve?

Question

i have no idea but in a very simple circuit i found on the internet the base on the transistor was not being used how can this be

Answer 1

It is probably being used as a rectifier, though a collector-emitter connection should not conduct in either direction. Although the base may have no connection shown, it is being used because it is the physical connection between the collector and emitter.

It's just possible that the circuit had been drawn incorrectly or that the base connection was assumed.

Answer 2

Base Emitter bias can be introduced in several ways. A common method is to raise or lower the emitter potential with a resistor and tie the base to ground or the plus bus. In some cases The actual input device such as a sensor or microphone may supply the bias when connected to the base.
To keep the drawing more universal the input device may be left out since any signal source would work with it.
In an analog circuit where it is necessary to faithfully reproduce the shape of the input waveform at the output, it is necessary to pay closer attention to base components and bias resistor values.

Answer 3

Assuming that the circuit is drawn correctly, it could be used in place of a avalanche diode if a resistor is placed in series with it.

When the collector to emitter voltage exceeds a certain value, the junction breaks down and current begins to flow (similar to zener avalanche breakdown) between emitter and collector.

The value of the resistance decides the safest value that the transistor can handle without self destruction.

Some consider it a crude method, other hail it as example of creative mind - depends on the situation and components on hand!!!

Answer 4

The base is just the connector it is a know factor so it is not shown. The only reason for showing it would be for maybe resistance is needed. Ones making the print are the ones that decide to either show base or not show base it is up to the one that draws the print.

Answer 5

About the only thing I can think of is that they're measuring leakage current to indirectly measure temperature. Icbo goes up very predictably with temperature so, if you calibrated at one temperature, you could make a pretty fair thermometer.

Or, more likely, as others have mentioned, it might just be a misprint.


Doug

Answer 6

Well for an amplification of a certain voltage the input cathode and base goves amplified signal voltage between base and anode .

Answer 7

you can put that circuit in PSpice and simulate it see what happen