[chancelot]

Hi everybody,
i've been reading the forums here for a while now and I thought I needed some guidance with my new tool. I recently became the proud owner of a tektronix 5110 oscilloscope. It seems to be in excellent working condition and has a multitude of buttons, knobs and probe connectors. It came with some swappable modules which were; a four channel amp, a single channel amp, and the time base amp. (that is 5A14N, 5A24N and 5B10N respectively)... I have one or two ideas at the moment of things i could possibley use it for. In the world of audio and amplifier DIY where does my oscilloscope fit? Could it be of some use in a future PPA or Millet build?

ideas i've thought of...
1. poke around on my cmoy circuit
2. buy a govibe and poke around on it
3. find the brown noise

What other uses could i possibley get out of this thing?

As for the welcome, i've already bought two ksc75's, two ksc35's, PortaPro2, px100, 5th gen ipod, and a pair of MS1's which i may never part with. this hasnt hit my wallet too hard yet although i see MS2i's on the horizon.

 

[morsel]

Door stop, window prop, cat heater, egg beater, gerbil hut, biplane strut,
its uses are only limited by your imagination.

OK, another answer. Get a signal generator so you can observe sine and square wave response of amps you are testing.

 

[fewtch]

How about *building* a signal generator to watch its output on the scope?

Edit -- after that, get a styrofoam head and embed microphones in its ears. Then set up a website with relative measurements of the frequency response and other behaviors of various headphones.

 

[mirlo]

Quote:

Originally Posted by fewtch How about *building* a signal generator to watch its output on the scope? Edit -- after that, get a styrofoam head and embed microphones in its ears. Then set up a website with relative measurements of the frequency response and other behaviors of various headphones.

Or put a neural probe in the cat.

 

[amb]

Quote:

Originally Posted by fewtch How about *building* a signal generator to watch its output on the scope?

I am glad you put that smiley there...

Building an accurate function generator with very wide bandwidth (going from a few Hz to many MHz), low distortion (sine waves), fast slew rate (square waves and triangle waves), and with features like sweep, ramp, and other niceties is not a trivial undertaking. There is a reason why lab-grade function generators are not cheap. We need high performance test gear because the amps we measure today are also very high performance. If the test instrument is not substantially higher in performance than the amp under test, then the test result would be largely meaningless.

Building a good function generator from a pre-engineered kit might be plausible for the average DIYer. Long ago Heathkit had some, but I am not sure nowadays any (that is not merely a toy) could be found.

 

[fewtch]

Quote:

Originally Posted by amb I am glad you put that smiley there...

When I referred to building a signal generator, I was more hinting at a fun/educational project that could be used to play with his scope than a highly accurate multi-function device for testing high end amps. At least that's what was in my mind when I posted. But thanks for pointing out that building a good signal generator is not trivial.

 

[tangent]

Quote:

Originally Posted by chancelot In the world of audio and amplifier DIY where does my oscilloscope fit?

Put an AD8397 into a gain of 1 circuit with no compensation, then learn to find and recognize oscillation. Then do it again, to start seeing the wonderful variety of oscillation signatures.

Quote:

Originally Posted by amb Building an accurate function generator with very wide bandwidth...is not a trivial undertaking.

True, although if you take out the wide bandwidth part from my edit of your statement, it becomes doable. A single-frequency Wein bridge sine wave oscillator with band pass filter on its output can give you a very pure test tone. From there you can add other circuits that turn that into a square wave or a triangle wave.

It's when you want to add wide range frequency adjustment that things get really tricky.

I have a commercial unit here that cost me something like $400 new that has nearly 2% THD on sine waves, and the square waves ring like a bell. I opened it, and it probably has around $100 worth of parts in it. (A typical mark-up for commercial gear.) That puts it in DIY land, but of course that means that you get another distorting, ringy unit. You'd have to spend a lot more to DIY something that works better.

 

[rickcr42]

Piece of cake with the right chip.Maxim has a replacement for the "old standby" 8038 signal generator the MAX038 that makes a damn fine bench top signal generator for testing

http://www.maxim-ic.com/appnotes.cfm/appnote_number/650

If you are trying to do serious distortion measurements then you want a dedicated sine wave audio signal generator with temp compensation.Pop "audio signal generator" or "low distortion sine wave generator" into google for enough hits to make your life miserable

 

[star882]

If you only need audio frequencies, a good sound card and some software is all that's needed for a function generator that can output any waveform within amplitude and frequency limits.