Electronics: How to ????????????????????????????????????????????????

U2222????

Do you mean a 2N2222?
Is it a 2N2222 or a 2N2222A Plastic or metal can?

Set your ohm meter on low ohms (thats normally the 1X scale.

Zero your meter.

Since you cannot get meter deflection C to E, you need to test C to B and E to B.
C will be on the outside leg (EBC BEC but NORMALLY EBC) so once you know the base, and the collector is always on the outside, you can figure out the rest.
 
A 2N2222 is an NPN transistor, and has many transistors that
can be substituted without modification(s) to exhisting circuitry.
With the use of an Ohm Meter set for R X 10; now you should be
able to read the proper values, determining if the transistor is bad.
From Base to Emitter will be about 400 to 600 ohms higher than the
opposition of the Base to Collector junction, because of the doping
used to make up the junctions, enabling the transistor to do it's job
as an amplifier or a switch. On a known good 2N222 (or a 2N3964)
the negative lead is connected to the Base and the positive lead of
the meter is connected to the Emitter. On the R X 10 scale, it should
read infinity. Reverse these leads. Now the meter should read (about)
122k or 122,000 ohms. Connect the positive lead to the Collector.
Connect the negative lead to the base. The meter should read infinity.
Reverse these leads and now the meter should read (about) 121k or
121,450 ohms.Basically, a Transistor is two diodes that (in the above
case) are placed back to back, or anode to anode. A PNP transistor
is a compliment of the NPN transistor; it's diodes are placed face to
face, being where the two diodes meet, is the base. Utilization of the
R X 1 scale is only good for checking for continuity, or short circuits.
If a transistor was shorted, one or both of the junctions will check as
shorted, or showing too low of a resistance rendering it useless. If a
transistor was open, one or both of the junctions will check infinity
(both ways) or a reading of a very high resistance, rendering it too,
useless. Feel free to e-me. Happy Holidays!
 
A 2N2222 is an NPN transistor, and has many transistors that
can be substituted without modification(s) to exhisting circuitry.
With the use of an Ohm Meter set for R X 10; now you should be
able to read the proper values, determining if the transistor is bad.
From Base to Emitter will be about 400 to 600 ohms higher than the
opposition of the Base to Collector junction, because of the doping
used to make up the junctions, enabling the transistor to do it's job
as an amplifier or a switch. On a known good 2N222 (or a 2N3964)
the negative lead is connected to the Base and the positive lead of
the meter is connected to the Emitter. On the R X 10 scale, it should
read infinity. Reverse these leads. Now the meter should read (about)
122k or 122,000 ohms. Connect the positive lead to the Collector.
Connect the negative lead to the base. The meter should read infinity.
Reverse these leads and now the meter should read (about) 121k or
121,450 ohms.Basically, a Transistor is two diodes that (in the above
case) are placed back to back, or anode to anode. A PNP transistor
is a compliment of the NPN transistor; it's diodes are placed face to
face, being where the two diodes meet, is the base. Utilization of the
R X 1 scale is only good for checking for continuity, or short circuits.
If a transistor was shorted, one or both of the junctions will check as
shorted, or showing too low of a resistance rendering it useless. If a
transistor was open, one or both of the junctions will check infinity
(both ways) or a reading of a very high resistance, rendering it too,
useless. Feel free to e-me. Happy Holidays!
 
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