Re: Scope trace fainter at faster Time/Div?

LanceM <[EMAIL PROTECTED]> wrote in 
news:[EMAIL PROTECTED]:

> An older 20 MHz dual channel Leader analog. Testing secondary ignition
> pattern on car, using inductive clamp for trigger (#1 spark plug wire),
> and capacitive p/u on inverted Chan 2 (on HT coil wire to distributor)
> 
> Is it normal for the trace signal to progressively & substantially dim
> at faster Time/Div settings? Occurs on both Normal and Auto trigger. I
> don't think adjusting the trigger level helped, but will retry that.
> 
> Thank you,
> Lance
> 

I would think it is normal.The phosphor is energized less by a faster 
sweep(lower duty cycle),thus less light emitted. Note that at very slow 
sweeps,the brightness goes UP,if there is no dimming circuitry to protect 
the phosphor.Some scopes had burned phosphor(lines) due to slow sweep 
speeds at too high an intensity.Newer scopes have beam-regulating circuitry 
to keep trace intensity fairly constant over a wide range of sweep speeds. 

-- 
Jim Yanik,NRA member
jyanik-at-kua.net