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When using an ohmmeter what should be the results for an NPN transistor?
Wiki User
∙ 12y ago
When the positive lead is at point "P" which is the base and the negative lead is at either of points "N" which is either the emitter or the collector, then the ohmmeter should have a very low reading or reads short circuit. Also, when the negative lead is at point "P" and the positive lead is at either points "N", then the ohmmeter should have an infinite reading when the meg ohm range.
Wiki User
∙ 12y ago
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What is the main rule to be followed when using an ohmmeter?
The main rule to be followed when using an ohmmeter is to have the circuit under test de energized from the power source.
Can you measure a vacuum tube using ohmmeter?
Maybe, but not sure info would be useful. You can use ohmmeter to check that a tube's filament is intact. Broken/burned-out filament is most likely reason for dead tube.
How could unmarked diodes have its cathode leads identified using an ohmmeter?
Assuming the red lead of the ohmmeter is more positive than the black lead, then checking the impedance of the diode with the ohmmeter, in both directions, will identify the cathode as the black lead when the measured impedance is low. This, however, will only work if the voltage developed by the ohmmeter is greater than the forward bias voltage of the diode, typically 0.7 volts.
How do you test a transistor using cathode ray oscilloscope?
Yeah...its possible to test the transistor using Cathode Ray Oscilloscope (CRO). CRO provides a function called "Component Testing". Just connect the transistor terminals between two pins provided by this function and you can observe the patterns on the CRO screen. Normally, in case of transistor, The operation is divided in few parts. 01. Observe the pattern for CB configuration. ---- For this, connect the terminalsfrom CRO between this Collector and Base terminals and you can observe the pattern shown by CRO. Same procedure should continue for CE & BE configuration so as to test the transistor.
What is saturation and active region in a transistor?
The output current of a transistor is controlled by the current in the 'base' input: Increasing the control current will increase the output current in a more or less linear fashion. In the saturation region, this is no longer true: The transistor is nearing the limits of how much current it can conduct, so increasing the control current further has little or no effect. When using a transistor as an amplifier, you want to stay away from the saturation region as it would distort the signal you are amplifying. When using a transistor as an on/off switch, as in digital circuits, being in the saturated region is 'on' and a normal mode of operation.
What are the instruments for the study of the gain of a two stage RC Coupled transistor amplifier?
depends on whether you would like calculate or measured results. if you want calculated resulted, then your best bet would be to use an oscilloscope. if you want calculated results, then there are formulas for finding out the voltage, current, impedance, and individual results from each component using the capacitive reactance, voltage, and type of transistor. are you using a summing transistor, inverting amplifying transistor, amplifying transistor, or a different transistor? also are you using DC or AC voltage or current? you need to tell me what type of transistor you are using?
How do you identify a pnp and npn transistor practically?
Using an ohmmeter on its lowest scale, the base-emitter junction of a transistor looks like a diode. If it conducts with the base positive, the transistor is an NPN. If it conducts with the emitter positive, the transistor is a PNP. (Of course, you need to know which probe of your ohmmeter is the positive one. DON'T assume anything. Some meters swing one way, some the other way. The only way to know for sure is to check it with another meter, used as a voltmeter.)
Should the ohmmeter be connected to the circuit while the power is being applied or only when the circuit is turned off?
Turn off the supply before using the ohmmeter,it will damaged your ohmmeter when supply is present.
What is the main rule to be followed when using an ohmmeter?
The main rule to be followed when using an ohmmeter is to have the circuit under test de energized from the power source.
How can you test a transistor?
Testing Bipolar NPN or PNP transistorsIf you have an ohmmeter or continuity tester, it's not hard to check a Bipolar transistor. First, set your ohmmeter on "Diode" mode (or turn it to the lowest Ohms range.) Identify the transistor's Base pin. Next, for NPN transistors connect the ohmmeter's positive lead to the base. Briefly touch the other meter lead to the transistor's Collector, then to the transistor's Emitter. Both connections should show a low-hm's reading: a diode-type connection. Then, connect the meter's negative lead to the transistor Base, and again touch the other meter lead to each of the other transistor pins. The meter should show open circuit or infinite ohms on both pins, indicating reverse-biased diodes.If the transistor is PNP, just reverse the meter leads to perform the above tests. Touch the meter's negative lead to the Base pin, then verify that the Emitter and Collector pins behave as "turned on" diodes. Touch the meter's positive lead to the Base, and verify that the Collector and Emitter are acting like turned-off diodes.Testing for "transistor" function, locating the EmitterIf you use your wet fingers as a resistor, sometimes you can use your ohmmeter to check for amplifier function, and also detect which pin is the emitter. First test for diode function in order to locate the transistor's Base pin. Connect your ohmmeter between the other two pins (no connection to Base, yet.) Wet your fingers and touch the Base at the same time as one of the other pins. Note the ohms reading if any. Then touch your fingers between Base and the other transistor pin. Was one ohms reading much lower than the other? If not, then reverse the ohmmeter leads. Then touch your fingers between Base and one pin, then Base and the other pin. When you find one ohmmeter reading which is much lower than all the others, then you've located the proper polarity for transistor amplification. During the lowest ohms reading, your wet fingers were connected between Base and Collector. The other transistor pin then has to be the Emitter. (You can also perform this whole test more reliably by using a 1K resistor in place of your wet fingers!)Testing an FETIt's a bit more difficult, but FETs can be tested using an ohmmeter, a 9v battery, and wet fingers. (During low-humidity winter weather, when high static voltages are present, you might want to wear a grounding strap!) First let's test for correct operation of a common N-channel depletion-mode MOSFET. Connect your ohmmeter between the FET's Source and Drain pins, with the positive meter lead on the Drain. While watching the ohms reading, touch the 9V battery's negative terminal to the Source or Drain, then use your wet fingers to briefly connect the battery's positive terminal to the transistor Gate pin. The ohms value between Source and Drain should become low. Remove the battery and briefly touch your wet fingers between Source, Drain, and Gate. The ohms reading should go high again. You've just applied and removed a charge to the floating Gate pin, switching the transistor on, then off again.For testing a P-channel FET, just reverse all the polarities. Connect the ohmmeter to Source and Drain (positive meter lead to Source.) Use your wet fingers to touch the battery's negative terminal to the Gate pin (with battery positive touching Source or Drain.) That should make the ohms value go low.)NOTE ON ALL OF THE ABOVE: I assume that the transistor is disconnected from any other circuit. If your transistor is soldered into a circuit board, most of these tests won't work.
How do you identify the transistor wheather npn or pnp?
You can use a ohmmeter, assuming the ohmmeter presents more than 0.7 volts in the open circuit state.If you know which pin is the base, put the plus lead on it and check the emitter and collector. If you have continuity, the device is NPN. If not, reverse the leads, and if you now have continuity, the device is PNP.If you don't know which lead is the base, or you want a general go/nogo check of the transistor, connect the ohmmeter in all nine configurations. You should find continuity in only two configurations. Of these two configurations, if the common lead is the plus lead, the device is NPN, otherwise it is PNP. This will also identify the base. (Unfortunately, you cannot identify the collector or emitter using this technique.)
Is an ohmmeter connected in series or parallel?
You almost NEVER do. 1) The circuit should be off and/or disconnected when using an ohmmeter. 2) It should be in parallel with the component as far as the rest of the circuit is concerned, but alone in series with the device its measuring.
When using an ohmmeter to check the continuity of generator field coil the field coil should?
Read less than 1 ohm
How the resistance is measure?
Using an ohmmeter, Wheatstone bridge, etc.
What precuation must be taken when using an ohmmeter?
Be certain the circuit is de-energized and discharged before connecting an ohmmeter.Do not apply power to a circuit while measuring resistance.When you are finished using an ohmmeter, switch it to the OFF position if one is provided and remove the leads from the meter.Always adjust the ohmmeter for 0 (or ∞ in shunt ohmmeter) after you change ranges before making the resistance measurement.
How do you check transistor faulty or not?
the best way is to compeair the data sheet of that transistor to the readings of that transistor. . . . .and u can get the readings of that transistor by using a fungction genrator and a c.r.o
Why the gain of pnp transistor is low?
it doesn't have to be. depends on design of amplifier using transistor.
