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Electronics => Beginners => Topic started by: aabbcc on February 13, 2018, 02:03:57 pm

Title: Help with oscilloscope readings
Post by: aabbcc on February 13, 2018, 02:03:57 pm

So I recently got my Rigol DS1054z and wanted to use it straight away to tune a synth I have. I've never really used a scope before so here goes.

Going over the service manual for the synth and the manual for the scope I realize I have no idea what I'm looking for  :scared:

What values should I be looking at when scoping for the different adjustment points below? Period? Width? Etc.

Title: Re: Help with oscilloscope readings
Post by: David Hess on February 13, 2018, 02:37:44 pm

For the first three you are looking for a period measurement.  For the last one, you will need to do it by eye or using cursors.

Title: Re: Help with oscilloscope readings
Post by: newbrain on February 13, 2018, 02:42:35 pm

A modern scope, even a simple one as the Rigol 1054Z, can be a bit overwhelming for a newcomer.
For a general understanding of how scopes works and can be used, you can have a look at W2AEW course (https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/).

For your specific questions, I'll try to give some brief hints.

• One channel is enough, let's say you use channel 1 (the yellow one)
• You should have an idea of the amplitude of the signals, in this case I would think they are ground referenced and some volts peak.
  So, I would start with 5V per vertical division, making sure that you are using the probe in 10x mode, and the scope is also set for a 10x probe, then go down (2V/div, 1V/div etc.) so as to have the screen optimally filled up.
• Timebase (horizontal) depends on the specific TP you are checking: to see 2-3 cycles on the screen, this could something like 2ms/div for TP1, 500µs/div for TP2, 500µs/div for VCO (but see below) and 2ms/div for VCF. You can then adjust the timebase to you liking.
• The trigger can be set to positive edge, about half the peak to peak value of your signal. The last test point might need some care in setting the level to have a stable waveform.

About the VCO setting, I've assumed that CL and CH are the C note below and above central A, so about 260 and 520 Hz. The idea is to set the VCO so that an octave is exactly double the frequency of the previous one.

The measurements can be done by looking at the grid (the old days way) or using the scope provided measurement as already suggested by David Hess.