Are NPN and PNP transistors interchangeable?
Answer: NPN and PNP transistors are interchangeable if you remember one simple rule: A bipolar transistor is essentially two back-to-back diodes with the base being the common connection. The collector (C), on the other hand, goes to +V — in effect, reverse biasing that diode.
Can you convert PNP to NPN?
If you need one PNP in a mostly NPN circuit, there is no general solution. For example, if the PNP transistor was being used as an emitter follower, and you have the headroom, you may be able to use an NPN in common emitter, with Rc=Re so that its gain is (approx) 1.
Where is PNP transistor used?
PNP transistors are used to source current, i.e. current flows out of the collector. PNP transistors are used as switches. These are used in the amplifying circuits. PNP transistors are used when we need to turnoff something by push a button.
How does a PNP BJT work?
The PNP transistor turns on when a small current flows through the base. The direction of current in PNP transistor is from the emitter to collector. The letter of the PNP transistor indicates the voltage requires by the emitter, collector and the base of the transistor.
What is PNP transistor working?
Then, PNP transistors use a small base current and a negative base voltage to control a much larger emitter-collector current. In other words for a PNP transistor, the Emitter is more positive with respect to the Base and also with respect to the Collector.
How PNP transistor works as a switch?
PNP transistor works same as NPN for a switching operation, but the current flows from the base. In this switching, base current flows when the base voltage is more negative. Simply, a low voltage or more negative voltage makes the transistor to short circuit otherwise, it will be open circuit.
How do you test a PNP transistor?
If you are testing PNP transistor, the meter should show a voltage drop between 0.45V and 0.9V. Hook the positive lead from the multimeter to the to the COLLECTOR (C) of the transistor. Hook the negative meter lead to the BASE (B) of the transistor. For an good NPN transistor, you should see “OL” (Over Limit).
How do I know if BJT is working?
Use the multimeter on a low ohms scale. Check the resistance between the base and emitter with the red lead on the base and the black lead on the emitter, then repeat with the red and black leads reversed. If the transistor is good, you should get a low reading and a high reading.
Can I test a transistor in circuit?
Potentially faulty transistors can be tested with a digital multimeter, but the type of transistor will determine the type of test used. If testing a Junction Field Effect Transistor, or JFET, you will need to use two 1000-Ohm resistors in addition to the multimeter.
How do you know if a transistor is bad?
Connect the red probe in turn to each of the three leads. If the other two leads don’t give the same reading when touched by the black probe, the transistor is PNP and it is bad. Multimeter tests determine if a transistor is blown (open or shorted) and provide a rough estimate of the transistor’s ability to amplify.
What may cause a transistor to fail?
Failures can be caused by excess temperature, excess current or voltage, ionizing radiation, mechanical shock, stress or impact, and many other causes. In semiconductor devices, problems in the device package may cause failures due to contamination, mechanical stress of the device, or open or short circuits.
How do you know if a transistor is open?
A first check is to think of the transistor as consisting of two diodes, connected “back to back”. Then, using the “diode test” mode of your meter (if it has one), verify that the emitter-base diode, and then the base-collector diode, both check out as normal diodes.
What is stuck open fault?
Transistor Fault model is a Fault model used to describe faults for CMOS logic gates. At transistor level, a transistor may be stuck-short or stuck-open. In stuck-short, a transistor behaves as it is always conducts (or stuck-on), and stuck-open is when a transistor never conducts current (or stuck-off).
Do transistors leak?
The primary source of leakage occurs inside transistors, but electrons can also leak between interconnects. Leakage increases power consumption and if sufficiently large can cause complete circuit failure. Leakage is currently one of the main factors limiting increased computer processor performance.
Is leakage current dangerous?
Medical Equipment The leakage current is very dangerous if it exceeds the permissible safe limit. Only a small current needs to flow through the human body to cause harm and can be fatal for patients whose immune systems are already weak.
Does leakage current flow when transistor is on?
consider common emitter configuration. when the switch is open, the emitter base junction is an open circuit and so the value of input or base current is zero. But a leakage current 1CEO flows between collector and emitter.
What is transistor leakage?
The current in the blocking direction in a diode is called the leakage current. There are no leakage currents in the transistor with its two diodes if one. electrode is open at a time.