Oscilliscope

[4krow]

 With tongue in cheek, I am deciding whether or not to get a used scope somewhere. Fact is, I know very little about them and want to learn, so that I can use it in my shop on occasion. Perhaps one of you out there has a recommendation for maybe a dual trace scope?

[Paul Birkeland]

It's more important to first find somebody to help you learn to use the scope.  Once you find that individual, they may have one sitting around or know where to get one inexpensively. 

-PB

[Strikkflypilot]

I just procured a Rigol DS1054z, a four channel, 50MHz, 100MHz unlockable scope that seems fairly feature packed for its price and apparent build quality.
Would be great if someone could give some pointers to what can be tested and how in these Bottlehead products.

[Natural Sound]

A good place to start would be Tektronix 465, Tektronix 2235, Tektronix 2236. Make sure it comes with a set of probes.

As I recall Doc B. posted a link to some kind of Oscilloscope class or FAQ in the past. Unfortunately I didn't bookmark it. Maybe he will see this and post a link.

EDIT: Just found the link. http://bottlehead.com/smf/index.php?topic=11.msg517#msg517

[4krow]

Hey very good NS, this gives me a starting place at least. It's just that I have no way of measuring frequency response, or the effect of a filter,etc. Swapping parts is ok on a proven design or mod, but beyond that, I just got to learn more. Thx for the recommendations. 

[Paul Birkeland]

You don't really need a scope for that.  A laptop, USB sound card, and Arta will take care of that for you.

[Doc B.]

I'll add that the older Tek scopes, as great as they are, are getting rather long in the tooth and often need service. I have a TDS420 that is a great scope, but it's been a PITA at times as various circuits have required recapping and such.

Peebs and I were trying to get some really low level noise floor measurements last week and though the scope was working OK we had so much crap from a local radio station coming in through our test cables that we couldn't get a good reading. The irony is we are in a metal building that you can't even use a cell phone in, and yet we still had interference. Budget in some good cables and probes as well as the scope if you are going to attempt any low level measurements.

[Strikkflypilot]

I would like to look at how caps clean up the signal/power output, but is looking at filter caps in the PSU as deadly as measuring mains?

[Paul Birkeland]

I would like to look at how caps clean up the signal/power output, but is looking at filter caps in the PSU as deadly as measuring mains?

With a 10X probe and the cap on AC coupling, this is not dangerous.

[Paul Joppa]

With a 10X probe and the cap on AC coupling, this is not dangerous.

However, many 10x probes have a limited maximum DC voltage - mine are rated 250v, even when AC coupled on the scope. 100x probes exist but are ridiculously expensive...

[Strikkflypilot]

With a 10X probe and the cap on AC coupling, this is not dangerous.

Good to know.
I ought to read up on this stuff, kinda unfair to exploit Your superior knowledge like this:)
I especially want to find out when never to use an oscilloscope and when it is safe and how.
I am looking forward to comparing my pretty beefed up crack and the one I expect in the mail soon, one stock with speedball and the other with big fat film caps and choke...

And thanks, Paul Joppa, I will check the specs of the probes, I know they do 10x and are 150MHz but that's it...

[Doc B.]

Never use an oscilloscope to make flan.

Never use an oscilloscope to pluck your eyebrows.

Never use an oscilloscope to spray paint.

[Natural Sound]

Never use an oscilloscope to make flan.

Never use an oscilloscope to pluck your eyebrows.

Never use an oscilloscope to spray paint.

Excellent advice.

[4krow]

Doc,

  That's the thing about me, I am pretty resistant to change. As of this day, I have never owned a cell phone. And then I was only taught about computers because the company was going that direction. Having said that, I know that I can't argue the convenience of the new technology. And, Take your advice to heart when it comes to the old equipment not getting any younger. For my purposes though, I would only be measuring filters and their effectiveness, and maybe some trouble shooting now and then. Not much in the way of radio signal in this part of Wyoming, but it wouldn't surprise me either to have some sort of RFI.

[Paul Birkeland]

For my purposes though, I would only be measuring filters and their effectiveness

An oscilloscope is not really the best (or most affordable) tool for this job.