how to find BI-POLAR transistor BASE COLLECTOR and EMMITTER
turn on your digital multi meter 2 k range ,then connect your digital multi meter RED PROBE (red wire) any lead of transistor. remaining two leads of transistor connect one by one with digital multi meter black probe (black wire)if this two leads showing same resistance 150 ohm's to 950 ohm's , the pin which you are connected red probe (positive probe)is base of the transistor, and we can call the NPN transistor.
which lead showing one side reading in the transistor (base to collector and emitter) this lead called BASE
CHECKING A TRANSISTOR
very simple procedure to check common PNP and NPN TRANSISTORS USING THE DIGITAL multimeter.PNP TRANSISTOR CHECKING METHOD
STEP 1
Turn on your digital multi meter continuity mode or 2k range then keep negative probe( black probe) on base of the transistor and other positive probe ( red probe) on collector. if multi meter showing 150 ohm's to 950 ohm's resistance, remove positive probe from collector and connect on emitter of the transistor if show same resistance this transistor is PNP.
put positive probe on base and negative probe on collector and after emitter, if multi meter both leads not show any reading, that is means transistor is good.
STEP 3
checking collector to emitter is there any short , for this put multi meter negative probe(black probe) on collector and positive probe (red wire) on emitter it will not show any reading.
again connect red probe on collector and black probe on emitter in this direction all so it should not show any reading on multi meter.
this 3 tests pass then only we can confirm transistor is good.
NPN TRANSISTOR CHECKING METHOD
STEP 1
Turn on your digital multi meter continuity mode or 2k range then keep the multi meter red wire on base of the transistor and other black wire on collector if meter showing 150 ohm's to 950 ohm's resistance, remove black wire from collector connect on emitter of the transistor if it show same reading it is NPN TRANSISTOR .
STEP 2
keep multi meter negative probe on base of the transistor and positive probe on collector then connect emitter if multi meter not showing any reading that is means transistor is good.
STEP 3
checking collector to emitter is there any short, for this keep the multi meter negative probe black wire on collector red wire on emitter it should not show any reading
again connect red wire on collector and black probe on emitter in this condition also same results should then only we can confirm transistor is good.
if 3 tests pass we considered NPN bipolar transistor is good.
GERMANIUM TRANSISTOR CHECKING
for GERMANIUM transistor also same checking procedure but collector to emitter might show reading 450 ohm's to 1.1 k ohm's resistance one side.
connect negative probe on collector and positive probe at emitter it should show reading around 450 ohm's to 1.1k ohm's resistance.but it should not show reading on reverse direction
some transistor specially those which are used in horizontal out put section transistors have internal diode collector to emitter. this type of transistor also collector to emitter it show reading. these transistors may show base to emitter reading both sides, both these readings will be different.
EXAMPLE: BU 208D, BU508, 2SD 1308,
if you connect black probe on collector red probe on emitter it show resistance 450- 900 ohm's. but it should not show reading on reverse direction. then only transistor good working condition
0 Comments