[sdiy] first oscilloscope help

[Needham, Alan]

My best (highest spec) scope at the moment is a 15MHz Telequipment "boat
anchor" D65. It was made somewhere in the mid 1970's.
I consider 15MHz to be more than enough for any audio work, I use mine
for HF radio and microcontrollers as well, although a logic analyser is
a better tool for the latter. I have given my 'scope a basic recal but
it isn't intended to replace a multimeter, a 'scope just can't give the
resolution!

That http://www.doctronics.co.uk/scope.htm tutorial shows a test lead
that terminates in crocodile clips (about a quarter way through the
article), this is sometimes more convenient than a probe (but I wouldn't
bother with the compensation adjustment for that!)
You may also find this useful :-
http://www.electro-tech-online.com/electronic-theory/212-using-oscillosc
opes.html

Your idea of connecting a turntable to the 'scope will work but I think
the novelty will wain quite quickly, you may get more lasting enjoyment
from using two oscillators to drive the two inputs and draw wild
Lissajous figures.
For audio, any old bits of wire will do (I bet that causes some flaming
mails!), cheap screened cable is better for the turntable idea so that
you don't send noise back into the audio amp.

	HTH, Alan


-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Nathan M.
Reeves
Sent: 13 January 2009 16:18
To: synth diy
Subject: Re: [sdiy] first oscilloscope help

I got a tektronix T922R locally from a guy who buys bulk equipment  
from military and government labs  etc etc...

This one was used at Ampex and was last calibrated in 1988 or  
something like that!

But hey it  was $20 and it works, though I did have to buy a P6006  
probe for it...and calibrate it.

By the way i have been meaning to ask if 2x 15MHz is enough bandwidth  
for most (if not all) synth DIY?

I dont have any micro pics or anything (yet?) just want basic voltage  
measurements and something with the ability to help me troubleshoot.

Also, How would one make a cable to hook up audio outs (RCA, 1/4" TS  
or TRS) to the scope channels?

Say I plug in my LEFT phono turntable to ch1 and RIGHT to ch2....and  
use dual trace, will i get neat graphs?

I am guessing the I dont even need the BNC type connector, i can use  
my probe to connect GND to SHEILD and the + pin?

My idea is to hook up audio outputs to my scope channels....for a  
SCOPE DJ SET at the local artsy fartsy venue (in atlanta this is call  
eyedrum http://www.eyedrum.org/)

I assume this would be ok as long as the impedance of the cable is ~50  
OHM, roughly the same as the probe

  though I think you can adjust compensation (is that what 1x versus  
10x is, the attenuation?

Can I hookup both and to CH1 and CH2 and get some neat graphics?  or  
lissajous curve traces?

I found this tutorial

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


I built the voltage divider with the cermet mic and it was neat to see  
my voice on the scope...talk about NON

sinusoidal!  OOOOOOOOOOOH,  AAAAAAAAAAAAAH, EEEEEEEEEEEEE

so much for my career as a singer 8^p

I recommend looking around locally for one, ham fest, or craigslist,  
shipping is expensive and most of these

things are tanks!

Cheers!

Nate


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