Scope Question - aka 'I'm being REALLY thick!'

[alteredsounds]

Sorry to sound completely thick but I've picked-up a Velleman HPS-10 Scope that seems cool but, although I have been building pedals and repairing them for about 3 years, I have never used a scope before but I am slowly learning.  My question is, if I hook-up the output of an electric guitar to the probe, shouldnt I be able to see a waveform for a plucked note? If so, I am lost to what setting I sshould use as I think I have tried everything. 

Many Thanks,

[Arfman]

Sorry to sound completely thick but I've picked-up a Velleman HPS-10 Scope that seems cool but, although I have been building pedals and repairing them for about 3 years, I have never used a scope before but I am slowly learning.  My question is, if I hook-up the output of an electric guitar to the probe, shouldnt I be able to see a waveform for a plucked note? If so, I am lost to what setting I sshould use as I think I have tried everything. 

Many Thanks,

I have a hitachi scope so bear with me. Set the input for .1 volts. You should see a waveform. Make sure that you have the ground connected.

Now, you will quickly find that this is not a very effective way to trace a circuit. I picked up a signal generator on ebay for about $25. That way I can run a sine wave into the pedal and then just trace to my hearts content.

Both with respect to pedals and amps i'd be lost without them. It can save you hours of work...

[alteredsounds]

Many Thanks, I will try that setting.  The manual with the Velleman is awful and I'm really hoping I've bought something that will be of use.  If all goes well, I will look at a full size one in the future but I also like the appeal of the portable scope.

[alteredsounds]

I feel pretty stupid  I've connected the probe to a lead coming from a guitar (volume is up!) croc earth clip is on the earth wire. I've been through (i think!) all the settings and cant get a waveform.  What am I doing wrong?  As soon as I can get this I can start learning to use the thing. 

[boogietube]

What is the spec of the sine wave you send through

[Dave_B]

FWIW, I use my old Diskman as a signal generator.  I run it straight into the effect being tested and raise the volume a little at a time.  I made a CD with different test signals on it (white noise, sine wave sweeps, pulses for triggering Envelope Followers, etc.) to use with my scope.  It works really well.

[Ronsonic]

First without a probe or cable plugged into the scope, get a visible trace and get it across the middle of the screen. You've got an intensity knob and controls for vertical and horizontal position. Near the input connector will be a switch to select AC, DC or Ground. Use the ground setting to find and center the trace - doesn't have to be perfect. Then select AC or DC to look at a signal. Don't even bother doing anything else until you've got a trace. You'll want any trigger select to be set on the input, set the voltage to .1V per Div and set the time to 1mS per div. It's easier to start with a steady signal instead of something that requires your hands like a guitar. The connection is straightforward, ground - ground and tip to signal.

Hope this helps you.

Ron

[boogietube]

I have a signal generator. What frequency and voltage should I set it to

[Dave_B]

I have a signal generator. What frequency and voltage should I set it to

1000hz and 1v p-p is a common starting point.

[alteredsounds]

I tried the settings suggested and still nothing, I connected a lead from my soundcard and used a tone generator program to produce a 1mhz signal but had to turn it up pretty bloody loud to get a waveform of any shape and that still want to big.  The probes are fine, I have 2 of them.  I posted on the Velleman site and they posted back that a signal from a guitar is too small and I would be unlikely to see it, is this right 

Maybe I should have just got a normal scope but this has put me right of scopes

[Dave_B]

You mean 1khz, right?  Assuming you're on a PC, make sure your Wave volume and 'Master' volume are high enough to generate a decent signal.

As Ronsonic said, you need to get a flat trace with nothing connected before you try to do anything else.

I can put a scope on my guitar and get a waveform.  Someone else will know the expected voltages, but I'm thinking my pickups were putting out around .5v.  Single coils will differ from HB's but either way, you should be getting something. 

You might make sure you're using the triggering correctly.  That's caused me some problems in the past.

[alteredsounds]

sorry typo 1khz yes.  I've had it up pretty lod tbh and it doesnt register much.  I've tried it with hb's and sc's and not a movement.  I'm sure it's this handheld scope.  Anyone any experience of these?

[Ronsonic]

Is there a scale on the input amplifier? Usually you'll see it graduated in volts per division and usually starting with something like .01v/div up to 10 or 20.

For looking at guitar level signals you'll want something like .1 v/div.

OR

Post a link to an online manual or at least a detailed photo and let's see what's there.

Ron

[alteredsounds]

Hi Ron,

Thanks for your help, here is a link to the product: http://www.velleman.be/ot/en/product/view/?id=348271 if I have got something useless, I will re-sell it and get a big scope.

Many Thanks,

[pjwhite]

Remember that if your scope probe is a X10 type, the voltage range setting on the scope will also be X10.  That is, to read 0.1 volts per division from a X10 probe, you should set the scope for 0.01 volts per division.  If your scope is not that sensitive, maybe that's your problem.

[alteredsounds]

I've got a x1 /10 switchable probe and nothing, maybe these scope just arent very sensitive? 

[Ronsonic]

Are you using the probe in X1? Contrary to the shorthand "X10" the probe means it is attenuating x 10, not multiplying.

It looks like it should handle this sort of work just fine.

It also looks like it does a whole bunch of fancy stuff and has an extensive manual.

First thing I'd try is to reset the unit and start over to make sure there aren't any weird settings stored (push the reset button and hold for 10 seconds). Set the probe and the scope for x1. Next, I see it has an auto timebase feature, use it. Set the input for something like .05 or .1 V/division. If you see a trace it should move. There's a trouble shooting drill on page 24 also. 

[alteredsounds]

ok, I've finally had time to get around to playing with this again and I think the problem is that the lowest you can set it is 5mv and that is just not low enough 

[Ronsonic]

5mV is plenty sensitive.

A guitar pickup easily does 20 - 100 millivolts.

Ron