I have a beat up 70's era analog scope that I still use sometimes because I understand it. I would happily use one of the arduino variants but they don't seem to do the same job.
If I put a steady signal into my analog scope Y input I can tweak the horizontal sweep time to give me a stable image and a good idea of what the frequency is. All of the arduino variants seem to be a steady crawl and I don't know what they're telling me.
Is there something I'm missing and is this what a newer scope would be like?
Gah! I can't imagine an Arduino having anywhere near enough processing power to function as a reasonbly-useful scope. Where are you finding these Arduino scopes?
Get a real stand-alone scope. Prices have really come down and a 2-channel 100 MHz unit for ~$1000 is realistically a life-long investment.
Arduino scopes are toys and inherently slow. Modern digital scopes resemble the old ones in many ways. In addition to the input amp's analog bandwidth you also need to watch the (real-time) sample rate.
Personal opinions:
USB-only scopes suck. A scope should be stand-alone.
Any type of scope running windows sucks (needing a virus scanner)
USB-only scopes suck. A scope should be stand-alone.
Yup.
Any type of scope running windows sucks (needing a virus scanner)
Well, as long as it's not networked it should be alright. I have a Tek logic analyzer running Windows 98 and it works really well. Boots up fast, no BSOD's, no viruses, never hooked up to the network
I miss the green/amber glow in the new ones
Yech...give me the fancy new digital LCD's any day
I'm demanding that any professional digital oscilloscope should not rely on the windows OS to work. There is at least one reputable company that sells high-end scopes (>20k$ and up) that ran on Windows 2000, maybe something more up-to-date now. Fortunately this is not a problem for the lower end devices affordable by people like us or small companies.
I find it hilarious that I could infect my oscilloscope with a virus just by inserting a usb stick to copy some data off it. And I haven't even started bitching about boot up times. Having to run a virus scanner on such a beast naturally doesn't increase speed. The measurement backend isn't affected by that, but anything related to user interaction.
Also I don't oppose running a virus scanner on linux, but currently that's only useful for preventing to spread a virus to the windows pcs out there.
the arduino scopes as pointed out are very slow in sampling, your old 70's scope is probably better
course yea you could go out and spend a couple car payments on a new slick lcd do everything model, I would love to myself
I have a 1987 model and while it is only 20mhz it is very useful and it has digital storage modes, so you can snapshot a live signals, zoom, and scroll while zoomed, along with OSD measurements such as a times voltages and frequency, and that was free
you can probably pick up a 90's model in decent shape for less than 100 bucks with similar features and higher speeds
I believe Arduino PWM signals are about 500 Hz? So well within the 1MHz bandwidth but a very narrow duty cycle (near 1% or 99%) could be missed.
5 million samples/second technically puts an upper limit of 2.5 MHz on the bandwidth. I'm guessing the analog-to-digital converter (whether they use an external one or the AVR's internal one) either has a lower bandwidth or they place a cheap RC filter prior to the A/D to prevent aliasing and that has a cutoff frequency of 1MHz so that there is at least some attenuation (~25dB) at 2.5 MHz.
All in all, you get what you pay for, but for teaching students about time-varying waveforms $49 is not a bad deal. And I'd much rather have a high-school student "accidentally drop" a $49 scope than a $4900 one
The only drawback is that if someone doesn't understand about bandwidth and they look at a signal on the scope to draw conclusions from it, their conclusions could be way off if the signal they're looking at has high frequency content. A little knowledge (or insufficient bandwidth) is a dangerous thing.
A little knowledge (or insufficient bandwidth) is a dangerous thing.
That's my observation with modern DMM meters, they always display a measurement number, but if one doesn't understand things like ranges, modes, test lead usage, true RMS Vs average AC, etc, etc a little knowledge can lead to large measurement errors or even damage. I recall a electrician at work having a DMM literally explode in his hands because he was trying to read a voltage but had the meter leads in the current position. Another tried to read 2.4kvac on a standard DMM, it kind of exploded also. It came down to poor training, as a instrument is only as smart as the person using it.
