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Basic: Connecting up an Oscilloscope?
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2  Next [all]
Author Basic: Connecting up an Oscilloscope?
Drumdrumdrumdrum
These is real basic. I'm about to purchase a second hand Dual-Trace Oscilloscope. I have no idea how to connect it to my modular system? This is not for DIY but just to see what is going on with my waves. I've had a look around but no one seem to get down to the basics of connecting to audio source.

Two main questions:

1. How do I convert the probes into a TS jacket, or do I?

2. Do I connect it to my main mix out. How do I get to see the basic wave and the effected wave.

Oh man! I have no idea? I've used a multimeter before but an oscilloscope is way over my head!

Thanks
diophantine
Drumdrumdrumdrum wrote:
1. How do I convert the probes into a TS jacket, or do I?

It is pretty simple, just ground to ring, signal to tip.

Better than the probes, though, is just to have a direct cable. You can get BNC to RCA adapters, RCA cable, and then RCA to TS adapter. That's what I do, since it was really cheap.

Drumdrumdrumdrum wrote:
2. Do I connect it to my main mix out. How do I get to see the basic wave and the effected wave.


To see two waveforms, you'll have to send signals to the two channels on the scope. (Just make sure that both channels are active, or you'll only see one!) Send the original waveform to a mult, and then send it off to the scope + the filter (or whatever). Then send the filter output to the other channel of the scope.
Drumdrumdrumdrum
Aha! Use a mult, of course! d'oh!

I was thinking that I'd be using up all my mix outs.........or having to fiddle around on the back end of the jacks. Whew!

It should not be too hard to make up some BNC to 1/8" TS cables

Thanks so much
satindas
useful info here.....

http://www.doctronics.co.uk/scope.htm
fate
I'm considering picking up a Tenma 20hz Oscilloscope for my modular, question though, Couldn't you use a BNC Female > RCA Male then RCA Female > TS Male? adapters and bypass need of the RCA cord?
Reality Checkpoint
satindas wrote:
useful info here.....

http://www.doctronics.co.uk/scope.htm


Just checked this link out and came across one of the funniest sentences I have read in ages!

"Faced with an instrument like this, students typically respond either by twiddling every knob and pressing every button in sight, or by adopting a glazed expression. Neither approach is specially helpful."

lolspew
decaying.sine
Reality Checkpoint wrote:
satindas wrote:
useful info here.....

http://www.doctronics.co.uk/scope.htm


Just checked this link out and came across one of the funniest sentences I have read in ages!

"Faced with an instrument like this, students typically respond either by twiddling every knob and pressing every button in sight, or by adopting a glazed expression. Neither approach is specially helpful."

lolspew


That is apropos for a modular synth forum!

I ordered a DPO tektronix o-scope. It's a cheap one with two analog channels. Can't wait for it to arrive. My Tek 453 has seen better days and I like the small size of the DPO.

That webpage will come in handy!
Filch
fate wrote:
I'm considering picking up a Tenma 20hz Oscilloscope for my modular, question though, Couldn't you use a BNC Female > RCA Male then RCA Female > TS Male? adapters and bypass need of the RCA cord?


Is 20hz enough bandwidth to show audio rate frequencies?
Christopher Winkels
I think he means 20 MHz.
Filch
Christopher Winkels wrote:
I think he means 20 MHz.


That would make more sense.

Can the dual channel scopes be set to show a single input utilizing the entire screen, or will it always be on half the screen?


**edit** Nevermind. I was able to find a video of a dual channel scope showing a single waveform on the whole screen. I'm learning here. smile
diophantine
Yeah, with most (if not all) dual-channel scopes you can move the waveforms anywhere across the screen, and scale them as much as you want (well, within the scales provided by the scope + probes). Some that have over 2 channels will have more limited controls over channels 3 and up, though (like more fixed scalings, and/or only vertical positioning).
fate
i got a tenma 20mhz dual channel scope off of ebay for $60 works perfect
hollowman
useful thread and the link that SATINDAS added was great!

applause Now to get a scope of my own!! hyper
batchas
I'm aware that the waveform of an envelope generator is shaping the signal, and that it's not the signal itself, but is there any way to make let's say an ADSR "visible"?
I read here that it isn't and I would like to understand why.
Maybe only meant on analog oscilloscopes?
I mean, I've already seen a few examples where an envelope is visible on a display, like here for instance or or here.

I kind of tried to make it "visible/readable" on my old analog oscilloscope with a point leaving its trace on the display, but it's not reliable or very good readable.
I think the prob is that the "time" factor is not setable to be long enough...
I could make a short vid to explain what I mean... I hope you don't interpret this as a bad joke. I am a noobie trying to understand some measurement principles.... THX!!!!


Or to formulate the question in a different way:
Is it possible to make the envelope shaping (an ADSR curve for instance, I mean it's also a 2 axis form, with y as time axis) visible on an oscilloscope?

I have sometimes difficulties to understand what a few Serge modules or even a "simple" Buchla 281e really do on the signal (depending on the function chosen) and visualizing how it shapes the signal in realtime would help considerably while learning electronic for DIY projects.
Tim Stinchcombe
Yes, it is eminently doable, though probably slightly easier on a digital scope - here is a simple example:



I actually powered up my analogue scope to check this was also visible on that, and at these speeds for the envelope, the overall shape was easily visible, you just need to ensure that the persistence or intensity is set so that the image 'lingers' long enough to be able to make sense of it!

Edit:

Quote:
I read here that it isn't and I would like to understand why.
I didn't read through all of that but I assume you are really querying the statement near the top :
Quote:
Non-periodic waveforms, or 'noise', ... contain no easily discernable pitches or amplitudes
which whilst true, doesn't mean to say you can't see them on a scope. Whilst it is true that oscilloscopes excel at displaying periodic signals, it is often easy enough to turn something like an envelope into a periodic signal by simply repeating it quickly, which is all I have done by using an LFO to gate my EG for the trace above. Because of the persistence problem with an analogue scope, if the repetition isn't often enough, it will be harder to see what is going on, but once you grasp the basic principles of operation of an oscilloscope, you will learn how to trigger the scope in order for it to be able to display all sorts of signals, not necessarily just those which are by their nature periodic, and hence easily captured!


Tim
batchas
I made a small vid to show what I meant with "a point leaving its trace on the display, but it's not reliable or very good readable + the time factor is not setable to be long enough"

I added some youtube audio track on each video to mute my explanations, so it's best seen with your volume set to zero!



And this is what I got tonight while trying to visualize some 281e functions. The main prob was the speed of my trig. I had to make it much faster to get better results.

The flimmering is always very disturbing so I'll now have to look at the trig "stability" knob on my scope (an advice from Tim), cause untill now this knob did not seem to do anything (on/off, but nothing inbetween).
So I'll check again and will also read the exact procedure in the manual which I also could download thanks to Tim!!!

daverj
To get a repeating waveform to appear stable on a scope you need to have the scope trigger off of the signal you are looking at.

I can't make out the controls on your scope, but I would guess that somewhere there is a switch that selects the trigger source. Be sure that it is set to the input that the signal is going into (often called input A or input B).

Then there will usually be a switch that chooses the direction of the trigger. With the type of signal you are looking at you want that to be set to "+" (the plus usually represents a trigger on a positive rising slope).

Then there will be a knob called something like Trigger Level. By turning that you are selecting the point on the input waveform that the trigger happens at. If you feed something in with a slow rising edge then turning that knob will make the scope trace start at various points going up or down that edge as you turn the knob. For the type of waveform you are showing you want to turn the trigger level knob down to the point where it is triggering at a point fairly low on the rising edge of the wave shape. Otherwise the beginning part of the wave will be off screen to the left and you won't see it.
batchas
Thanx a lot Dave!!!
I should have mentionned that Tim sent me very detailled explanations and a link to the original manual!
Nevertheless, it might help others + I'll have to check again cause as you are explaining here and how Tim did, it should work.
I'll show in a vid what the setting knob does to finetune, once I'll carefuly have read the manual to be sure I'm really doing all like it should be done.

For the moment I have the feeling I tried all and that this knob does not react as it should (instead of trig sync/ tuning values only an on/off effect), but it's only speculations: so... the manual is now waiting for me!
daverj
It looks like many of the knobs on that scope are dual knobs. So remember on those that the black part and the red part adjust different things. Also a lot of time the trigger level might include a switch when turned all the way one direction or the other. That would give an auto trigger level. When you rotate it so the switch is turned off then you adjust the knob to set the level.

There might also be a coupling switch for the trigger, to trigger on an AC or a DC waveform. Usually the DC setting works best, but sometimes you have to go with the AC setting.
swiv
daverj wrote:
To get a repeating waveform to appear stable on a scope you need to have the scope trigger off of the signal you are looking at.

I can't make out the controls on your scope, but I would guess that somewhere there is a switch that selects the trigger source. Be sure that it is set to the input that the signal is going into (often called input A or input B).

Then there will usually be a switch that chooses the direction of the trigger. With the type of signal you are looking at you want that to be set to "+" (the plus usually represents a trigger on a positive rising slope).

Then there will be a knob called something like Trigger Level. By turning that you are selecting the point on the input waveform that the trigger happens at. If you feed something in with a slow rising edge then turning that knob will make the scope trace start at various points going up or down that edge as you turn the knob. For the type of waveform you are showing you want to turn the trigger level knob down to the point where it is triggering at a point fairly low on the rising edge of the wave shape. Otherwise the beginning part of the wave will be off screen to the left and you won't see it.


Another scope newbie here, so this was really useful thanks thumbs up

Any ideas why using the above procedure/settings would still result in an unstable trace though? I'm worried that the scope I got for a gift recently doesn't trigger properly at all, both internal and external triggering doesn't seem to do anything (ie the trace just starts at a random point in Y, so I have to tune my signal specifically to get stable trace which kills the fun a bit). Here's a (poor - sorry!) photo of the front if it helps.



I am mostly just trying to use INT as the trigger source (so signal to be monitored - z3000 sine here - is multed to the Y input, triggering section set to INT, level and polarity switches set in all combinations, TIME/div set so a couple of oscillations are visible) but to no avail. seriously, i just don't get it Any help really appreciated!
asteraster
resurrecting this thread to ask if this cable will work from rack to scope

http://www.amazon.com/Bingfu-Pigtail-Center-3-5mm-Cable/dp/B00TI1W3ZM/ ref=pd_sim_23_1?ie=UTF8&dpID=41fhL-sgTQL&dpSrc=sims&preST=_AC_UL160_SR 160%2C160_&refRID=1B4DJH8ESHT4HMV78PCK

also have the Tenma 20Mhz

thanks!
Varikusbrainz
Hi

Would these alone be Ok to provide connection between eurorack and oscilloscope?

BNC Male to RCA female
3.5 mm Female to RCA Male
3.5mm patch cable

Thanks
Varikusbrainz
Varikusbrainz wrote:
Hi

Would these alone be Ok to provide connection between eurorack and oscilloscope?

BNC Male to RCA female
3.5 mm Female to RCA Male
3.5mm patch cable

Thanks


Or could I connect the probe directly to the tip and ground points on a 3.5mm mono jack socket and connect to the euro with a patchcable?
ImNotDedYet
Varikusbrainz wrote:
Varikusbrainz wrote:
Hi

Would these alone be Ok to provide connection between eurorack and oscilloscope?

BNC Male to RCA female
3.5 mm Female to RCA Male
3.5mm patch cable

Thanks


Or could I connect the probe directly to the tip and ground points on a 3.5mm mono jack socket and connect to the euro with a patchcable?


I connect euro patch cable to output jack, ground of probe for scope on sleeve, and non-ground of probe to tip.

I"m not sure about going the RCA route.
Varikusbrainz
Thanks but Im looking for a solution that doesnt require me to hold the probe, hence asking about connectors.

I ask as I side with caution but Im sure my solution will be fine.
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