Help, I'm Bipolar, I think?

[2FB327]

Bipolar junction transistor - Wikipedia, the free encyclopedia

Could someone explain to me the conventional flow of electrons in the NPN trainsistor? I have read and reread it and just don't get it, I know this isn't electronics 101, but isn't it just like a gate or a switch, to turn on/off or allow current to flow.

Such is the case: I have a superstar 120fm with a carrier, but no modulation, so I have taken voltage readings at the final tr20, driver tr21, and tr22.
In the rx mode I have supply voltage to the collector and zero to the emitter and base, when in tx mode the collector voltage drops to zero and the emitter and base go to 0.1 to 0.2V.

However at tr22, the rx readings are the same but when going to tx the collector drops to 2.0V and the emitter and base each show 0.6v.

In theory is this an indication that tr22 is doing it's job and tr21 is the culprit because it shows very little gain at the emitter or base?

I was able to find the schematic diagram on cbtricks, but without the voltage pin readings or knowing their meaning, I'm lost.

 

[Robb]

Take out the tranny and test it with the diode function on your DMM yet?
Pos lead of the DMM goes to the base lead for an NPN (neg lead goes to base for testing a PNP - BTW); then put the neg lead of the DMM to the collector lead first, and then test the emitter lead next. The emitter should read higher than the collector. Then test the trans for resistance in the same way; it should read very high/'overload' in the Megaohm range on both the emitter and collector leads. If your DMM has the hfE function; that should be the conclusive test after doing the other tests first.

 

[2FB327]

Thanks Rob, I know there is a joke in there somewhere with the "tranny".
I was hoping to avoid, testing each one at a time, but I will.

Back to the other question, is it the current flows into the transistor thru the collector and when it reaches a certain point it shuts off or goes to ground causing an open?

 

[Robb]

I used 'tranny' because it is easier to write than 'transistor'. No joke or pun intended. The 'tranny' base controls the current flow of the collector through the emitter.

 

[GnG8d]

While your questions seem pretty basic, the answer depends on whether you are asking about conventional current or electron flow. Also, is the transistor being used in a common emitter, common base or common collector configuration.

 

[2FB327]

While your questions seem pretty basic, the answer depends on whether you are asking about conventional current or electron flow. Also, is the transistor being used in a common emitter, common base or common collector configuration.

Could someone explain to me the conventional flow of electrons in the NPN trainsistor? was the question,

 

[Robb]

Could someone explain to me the conventional flow of electrons in the NPN trainsistor? was the question,

The transistor's base junction controls the current flow of the collector through the emitter. The more/less it gets of a charge; the more/less it will allow flow through the collector out to the emitter. The base junction is the 'gatekeeper'.

 

[GnG8d]

Could someone explain to me the conventional flow of electrons in the NPN trainsistor? was the question,

LINK

 

[2FB327]

Thanks Robb, great explanition.