Quick Answer: Can Two Pn Junction Diodes Placed Back To Back Work As PNP Transistor?

What is the difference between a diode and a thyristor?

A diode is a 2 terminal device namely anode and cathode.

But a thyristor is a 3 terminal device, out of the 3 terminal, 2 are anode and cathode while the other is gate which is used to provide external triggering to the circuit.

The power handling ability of thyristors is comparatively better than the diodes..

What is the PNP transistor?

The PNP Transistor is the exact opposite to the NPN Transistor device we looked at in the previous tutorial. … Then, PNP transistors use a small base current and a negative base voltage to control a much larger emitter-collector current.

Does transistor have polarity?

Small bipolar transistors fall into two groups – NPN and PNP. The emitter of an NPN transistor is connected to – or towards – the negative line. And its collector is connected to – or towards – the positive line. An NPN transistor switches on – when current flows INTO its base pin.

Can we replace transistor by two back to back connected diodes?

Once a metal introduced in this path (which is what two back-to-back diodes represent) , no BJT functionality is possible. No. Two back to back diodes is NOT a transistor. The special property that makes a PNP or NPN sandwich a transistor rather than just two diodes is that the base layer is very thin.

What happens if you put a transistor in backwards?

The collector-base junction of a transistor is usually reverse biased and has a high breakdown voltage. … But when the collector and emitter are connected backwards then the emitter-base junction usually has avalanche breakdown which creates hot spots that reduce the hFE of the transistor.

What happens when the zener diodes are connected in series?

Yes, it is possible to connect multiple Zener diodes in series in order to obtain a desired Zener voltage, but in this case, care should be exercised as to Zener current, Iz. For series-connected Zener diodes, the maximum allowable Zener current becomes equal to the lowest one among their specifications.

How does a clamping diode work?

The clamping circuit fixes the voltage lower limit to zero, that is, the start of the signal is 0 V. The positive clamping circuit blocks the input signal when the diode is forward biased. During the negative half cycle of an AC signal, the diode is forward biased and allows electric current through it.

Is a transistor a rectifier?

THE TRANSISTOR RECTIFIER Rectification of alternating current with a single transistor has been considered. This simple circuit consisting of a transistor, a biasing diode and a few resistors can rectify a.c as low as 0.3V or even less.

Is transistor used as a rectifier?

A transistor can be used as a rectifier. When you connect base-emitter or base-collector region and use it as a diode, a transistor can work as a low current rectifier.

Can a transistor be obtained by connecting two semiconductor diodes back to back?

Can a transistor be obtained by connecting two semiconductor diodes back-to-back? No. Because in case of two discrete back-to-back connected diodes there are four doped regions instead of three and there is nothing that resembles a thin base region between an emitter and a collector.

Can you use a transistor as a diode?

DIODE AND SWITCHING CIRCUITS The base-emitter or base-collector junction of a silicon transistor can be used as a simple diode or rectifier, or as a zener diode by using it in the appropriate polarity.

Why transistor is not used as rectifier?

Since base is thin one and lightly doped, either of the two segment does not work properly as p-n junction diode, which is required for a rectifier. … That is why, a transistor can not be used as a rectifier.

Do diodes block voltage?

The key function of an ideal diode is to control the direction of current-flow. Current passing through a diode can only go in one direction, called the forward direction. Current trying to flow the reverse direction is blocked. … Any negative voltage produces zero current — an open circuit.

What is back to back diode?

Back to Back Diodes D4 and D5 are high voltage diodes used to standoff the high voltages that could be present on the input pins and D1 and D2 are used to prevent leakage currents while the input voltages are within the normal operating range.

What happens when two diodes are connected in series?

Diodes are connected together in series to provide a constant DC voltage across the diode combination. The output voltage across the diodes remains constant in spite of changes in the load current drawn from the series combination or changes in the DC power supply voltage that feeds them.

Is transistor a semiconductor?

A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit.

What is the difference between a diode and a transistor?

Put simply, a diode is a two-terminal semiconductor device and a transistor is a three-terminal semiconductor device. A diode can allow the flow of current in one direction while blocking the flow of current in the other direction.

Why emitter is forward biased?

Forward bias on the emitter to base junction causes the electrons to flow from N type emitter towards the bias. This condition formulates the emitter current (IE). While crossing the P-type material, electrons tend to combine with holes, generally very few, and constitute the base current (IB).