The commonest gotcha with a digital scope is aliasing caused by the sampling frequency being too slow. If you want to look at a 20MHz square wave you need to sample at >100MHz to have even an idea of what it looks like. I was snagged for a while looking at what was supposed to be a 4MHz PIC oscillator (using a Tek THS720) and seeing a perfect sine wave of several kHz, thinking something was very wrong but finally just changing the timebase clarified the situation. I would not have had the problem using my ancient Heathkit 20MHz single-trace scope that I had to throw out after a filter cap broke down and burned out a transformer winding: impossible to get parts. /\/\/\/*=Martin ----- Original Message ----- From: "Dave Dribin" To: Sent: Wednesday, February 06, 2002 1:18 PM Subject: Re: [EE]:Oscilloscope > On Wed, Feb 06, 2002 at 10:42:03AM -0700, Dal Wheeler wrote: > > ----- Original Message ----- > > From: Dave Dribin > > > > > Would an analog scope, like the Tek 465, be useful for a serial > > > digital signal, like the PS/2 port on a PC? I guess I'm asking, would > > > a used Tek 465 or a used TDS 210 be a better buy for a > > > beginner/hobbyist doing some PC integration projects? > > > > Anyway, if you're just tinkering at home, and can wait, maybe you could shop > > around and see whats available. If you get paid to tinker, I doubt you'd go > > wrong going for the TDS210. My old instructor used to say something like > > "You never regret having the proper tools, but you can often regret not > > having them." :') > > Yeah, I totally agree about having the proper tools. I'm just trying > to find the minimum I can skirt by with. If I got paid to tinker > (i.e. price really wasn't a limiting factor), I'd definitely go with > a new DSO. But if I can monitor signals like I2C and PS/2 with a used > analog scope, I'll probably go that direction. > > -Dave > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads