Hello,

I patched up the circuit as shown, however when it's ON, with the oscillator probe at point A, I could see only DC voltage (straight line), I was expecting some on/off action displayed on the screen. because PNP was used .
Any suggestion I could capture the waveform at point A?
I’m using a 20MHz oscillator scope.

Datasheet of BC327 is attached.
The LEDs were 1W, forward voltage 3.2V~3.6V

Thanks
oookey

 

The PNP has the collector tied to the base which means the transistor is fully on (actually acts like a forward biased diode. Your oscilloscope is seeing exactly what is happening. Why would you expect to see anything but DC at point A? You don't have an oscillator circuit.

 

quote: "The PNP has the collector tied to the base which means the transistor is fully on "

I agreed its fully on, the PNP will turn on when the base is 0 or more -ve, if base is +ve, the PNP off. When current passes through R, voltage builds up & off the PNP.
My idea is to let the LEDs on & off rapidly that our eyes never realised, the LEDs been off.
would the 20Mhz oscillator not capable to capture the freq?

 

A frequency of 0 will look a lot like DC...

 

The transistor is biased so it turns on and stays on. It's not the base voltage but the base-emitter voltage that determines the state of the transistor. The base-emitter voltage is a constant value once the transistor turns on. The transistor is configured as a diode. You need to read a tutorial on transistor operation.