Describe whats going on in this circuit

Okay... Replying to the original post,

I believe that the emitter of a (NPN) transistor puts up the same voltage as that what is supplied to the base (with a small drop). Consider it as a PN Junction diode.

The current that is available at the emitter is that that is coming from the collector as the base current is very small - few microAmpers.

The zener and the resistor forms a potential divider to give a constant stable voltage to the transistor base irrespective of the change in input voltage..

Either this is some strange kind of breadboard, or it's not hooked up right.

I see:
Red, Yellow, E, and C are connected together.
Base isn't connected to anything.
1.2K resistor isn't connected to anything.
Diode cathode is connected to Black.
Diode anode isn't connected to anything.

Summary: output equals input. Circuit has no effect.

Needs to be rewired after an understanding of the breadboard's interconnect is gained.

mneary said:

Either this is some strange kind of breadboard, or it's not hooked up right.

I see:
Red, Yellow, E, and C are connected together.
Base isn't connected to anything.
1.2K resistor isn't connected to anything.
Diode cathode is connected to Black.
Diode anode isn't connected to anything.

Summary: output equals input. Circuit has no effect.

Needs to be rewired after an understanding of the breadboard's interconnect is gained.

Click to expand...

YUP YOU ARE RIGHT i was doing this too late at night, thanks for pointing it out. Ill revised it

bananasiong said:

Why doesn't the schematic match with the connection on the breadboard?
As shown the yellow wire is the collector, so the red wire (assumed as Vcc) should be connected to the collector, and the other end of the resistor as well. The emitter should be grounded.
The pins of 2N3904 are EBC, the flat surface is facing you and the pins are pointing down.

Click to expand...

yes i conected most of it wrong, sorry should have revised it before. Where can i find the specs for my 2n3904 transistor? I'll google it see what i can find

I get datasheets from www.datasheetarchive.com . You can even select the manufacturer.