what oscillograph is I to need?

[lc516]

HI, friends
I want to learn PI homemake,what is a decent oscillograph for that?
40MHz/200mAs/S ?
Thanks!

[Carl-NC]

For most metal detector work you can get away with 20MHz, maybe even less.

[lc516]

Thanks Carl,

What about the sampling rate?
How much sample rate do i need?If in the future I hope to study in depth.

[Carl-NC]

I was thinking of analog scopes. A decent digital scope is going to be a bit more expensive, sample rate should be at least 10x the bandwidth. You can buy cheap made-in-China handheld scopes for a lot less than a real scope, I bought one once and found it to be unusable. They may have gotten better but I can't say.

[Mechanic]

If you can afford something like the Tektronix tds30x4 they are a nice digital scope. They go for reasonably cheap if you keep an eye on ebay. They don't have much storage. The bandwidth can be hacked if wanted. I have a tds3014B and it does everything I need it to do. Really handy for squeezing every last uS out of the PI.
That being said, there are other Chinese scopes that you can probably get for around the same price or cheaper with more storage and features, but I'm not sure how they perform. The TDS has a nice analog feel to it.

You will want at least 3 channels, 4 is nice.

I once bought a 20mhz usb scope. Used it once or twice and it is now in my junk box. Luckily I didn't pay much for it!

Cheers Mick

[SVEN1]

Recently picked up a perfectly working Philips 3070 for $60.

[Mechanic]

If you can afford something like the Tektronix tds30x4 they are a nice digital scope. They go for reasonably cheap if you keep an eye on ebay. They don't have much storage. The bandwidth can be hacked if wanted. I have a tds3014B and it does everything I need it to do. Really handy for squeezing every last uS out of the PI.
That being said, there are other Chinese scopes that you can probably get for around the same price or cheaper with more storage and features, but I'm not sure how they perform. The TDS has a nice analog feel to it.

You will want at least 3 channels, 4 is nice.

I once bought a 20mhz usb scope. Used it once or twice and it is now in my junk box. Luckily I didn't pay much for it!

Cheers Mick

I remember the other reason I went for that scope. It can be run from a battery, so can be taken out in the field to take live measurements on real dirt.

But really, an old analog scope will do just fine. I used one for years before finally deciding to upgrade. Was an old Kikusui COS5100, occasionally needed some love and every time it did I was worried it wouldn't be brought back to life! Needed the odd wack on the side too.

[waltr]

But really, an old analog scope will do just fine.

Yep, I use an older BK Precision 30MHz dual channel analog scope.
Works fine for detector building.