Oscilloscope

[Roger Dewhurst]

I have a Digitor 20 MHz (ex Dick Smith) oscilloscope which I bought some
years ago when money was burning a hole in my pocket. I unpacked it the
other day to familiarize myself with it. I tested various components,
resistors, capacitors, diodes etc. and found that I got two quite different
respones fro LEDs. Some generated the right angled trace supposedly typical
of diodes while some generated the 9 o'clock flat portion of the trace but
the other half angled off to about 1.30. The Zener diode that I tested
responded as though it was an ordinary diode. Informative comment would be
much appreciated.

R

 

[Phil Allison]

"Roger Dewhurst"

I have a Digitor 20 MHz (ex Dick Smith) oscilloscope which I bought some
years ago when money was burning a hole in my pocket. I unpacked it the
other day to familiarize myself with it. I tested various components,
resistors, capacitors, diodes etc. and found that I got two quite
different
respones fro LEDs. Some generated the right angled trace supposedly
typical
of diodes while some generated the 9 o'clock flat portion of the trace but
the other half angled off to about 1.30. The Zener diode that I tested
responded as though it was an ordinary diode. Informative comment would
be
much appreciated.

** Could some of your LEDs be self flashing ones ?

What was the voltage of that zener ?

Might be too high for the CRO's test signal to operate.



........... Phil

 

[David L. Jones]

Roger Dewhurst wrote:

I have a Digitor 20 MHz (ex Dick Smith) oscilloscope which I bought some
years ago when money was burning a hole in my pocket. I unpacked it the
other day to familiarize myself with it. I tested various components,
resistors, capacitors, diodes etc. and found that I got two quite different
respones fro LEDs. Some generated the right angled trace supposedly typical
of diodes while some generated the 9 o'clock flat portion of the trace but
the other half angled off to about 1.30. The Zener diode that I tested
responded as though it was an ordinary diode. Informative comment would be
much appreciated.

A zener will look like a normal diode in the forward direction. The
"component tester" on your oscilloscope may not generate a high enough
voltage to break down the zener in the reverse direction.

They don't make many scopes with component testers these days!

Dave