Semi-OT: Scored an O-scope!

[Ed G.]

A friend of mine is a tech who works on oilfield diagnostic tools. While he was in Corpus Christi, he calls me and asks if I want an oscilloscope, that the company was getting rid of some stuff and he would grab it if I wanted it. I said I did.
It's an older Tektronix T922R, it's a dual-trace scope, and it works. Plus, he got me a probe lead to go with it, he said those things are pretty expensive too.

So far, I dicked around with it a little bit with some caps to see if you really could determine the outer foil on a cap. I did, and it was easier than I thought. The 'audiophile' guys believe if you hook up the caps's outside foil to the low impedance side of a circuit that there will be less HF rolled off and you will get a clearer sound. Dunno if this is more 'audiophoolery' or such, but when I have some free time I'll crack my amp open and try it out. Shit, it won't cost me anything.

Anyhow, I want to use this thing to check out amps and such, I realize I need a signal generator. I was wondering if anyone knew of any simple DIY signal generator schems out there. I guess I can make a 'dummy load' out of a big power resistor, and that should work.

[Peter Snowberg]

Congratulations!

Getting a scope is like opening your eyes for the first time.

For a signal generaor, any audio-speed oscillator from a 555, to an inverter based oscillator, to a phase delay based oscillator, to a negistor if you want to get way out there should all work just fine.

I tend to like a triangle wave over a square for tracing audio.

[Mark F]

I concur with Peter, having a scope is like opening your eyes for the first time! :shock: Even when you're not using it to troubleshoot or design, a scope is fascinating to, for instance, look at waveforms inside of AM-FM tuners,TV's etc. Beware of the High Voltage in TV's, obviously.  Congratulations and have fun!

[ejbasses]

Hi

Nice score!!!!

I once built i a function generator for someone using a dedicated Function generation chip. Try looking it up. it was pretty easy considering it was a pretty cool function generator.

Enjoy your new gadget. I envy you. hehehe

[Lonestarjohnny]

good goin Ed,
thats a good scope ya got, and there's a lot of info over at the Tektronix site.
you might check out the 2 tone Audio Oscillator over at   www.diyguitarist.com
Johnny

[brett]

Well done! :wink:
I use RG's 2 transistor sine wave generator.  1kHz at 1V for $1.  But I'm an o'scope neaderthal.

Have fun!!

[Paul Marossy]

RGs audio oscillator is really handy, I built it, of course. I also purchased a function generator off of ebay for something like $35-40, a Heath-Schlumberger that can produce sine, triangle and square waves from 10Hz to 1mHz. Not a bad buy.  

EDIT: There are also chips that you can buy that would allow you to build your own function generator. They are capable of simultaneously producing sine, triangle and square waves. They are kind of a pain to get running properly sometimes, though.

[Ed G.]

Thanks for the replies, guys. Some of those projects at Paul's site look promising, at least to get me started.