I would suggest you to buy digital oscilloscope like Atten ADS1062CML, ML options means large screen/extra RAM.
Really good USB PC oscilloscope costs a considerable chunk of money anyway, and you should take into account that input ground and USB ground may be connected. How good is input protection of PC USB oscilloscope against high voltage is also a big question. High level of input noise seem to be a common problem of dirty cheap USB oscilloscopes.
PS. You can connect AAtten to PC via USB port if you wish to acquire data.
Really good USB PC oscilloscope costs a considerable chunk of money anyway, and you should take into account that input ground and USB ground may be connected. How good is input protection of PC USB oscilloscope against high voltage is also a big question. High level of input noise seem to be a common problem of dirty cheap USB oscilloscopes.
PS. You can connect AAtten to PC via USB port if you wish to acquire data.
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I've had good luck with the Picoscope. But in a similar price range the Atten does look very attractive, thanks for posting that.
Remember that many of these are limited to 8 bit resolution, is that's important to you. There is a 12 bit version of the Picoscope - for more money, of course!
If you don't need to measure past about 90Khz, I highly recommend using a good sound card with an interface. Quite a few of us here use that.
Remember that many of these are limited to 8 bit resolution, is that's important to you. There is a 12 bit version of the Picoscope - for more money, of course!
If you don't need to measure past about 90Khz, I highly recommend using a good sound card with an interface. Quite a few of us here use that.
I use this one too, and it is fine for general work, but watch out for the frequency generator, it has a drop off of several dB at around 10khz and above if I recall properly.
I also have the old PCS500 from Velleman and their PCG10 signal generator. Be warned that they are parallel port devices, something you won't find on many modern PCs. They properly isolated though and work well despite their quirks. It was my only scope for a while, which is why I eventually got an old 2-channel Tek. 
I can recommend TrueRTA - simple spectrum analyser and chirp frequency response plot. One key issue is to have a non-distorting clipper (to save the soundcard) and to have stepped/variable gain/attenuators to position the signal level between noise floor and clipping. The other issue is to accept a certain level of known hum earth loop, unless you use a laptop.
Ciao, Tim
Ciao, Tim
Most of the PC scopes have very limited input stages. Some offer a 100 mV range, but most of them are 1 V or 10 V only. That really limits things when you're trying to measure ripple or noise in the 1~10 mV range. I also question their level of input protection against over-voltage. It would truly suck to zap both your computer and PC scope because you accidentally connected the input to a few hundred volts...
Get a real scope. You won't regret it. If you don't need data acquisition, search the equipment & tools forum for recommended scopes. It's a question that comes up frequently.
~Tom
Get a real scope. You won't regret it. If you don't need data acquisition, search the equipment & tools forum for recommended scopes. It's a question that comes up frequently.
~Tom
Indeed. Nothing beats a real scope. But to toot the Velleman horn one more time, the PCSx00 are fully opto-isolated from the PC and can measure down to 5mV (though it gets a bit noisy). I still use it, especially when I want to capture a scope plot, use the spectrum analyzer, or use the frequency generator to do automated Bode plots.
To address the OP's original question, you may want to get a set of 100x probes for any scope that you get so that you can safely measure signals that are offset on high DC potentials. 10x probes are OK to a point.
As long as the input impedance of the scope is 1 Mohm. This isn't always the case with the PC scopes. Just something to check when buying one.
Having the data acquisition capability is handy at times. And many high-end scopes are basically a shielded PC with an oscilloscope attachment. But I've worked with some PC scopes - specifically, the rather expensive PXI modules by National Instruments - and found them very limited almost useless for any real work. But I am picky and opinionated. Maybe you have more patience than I do...
~Tom
I reckon that a simple pc scope software is great, and has its place - the idea should not really be to push the OP to a real scope, but rather assist in understanding the limits and simple workarounds.
I've found a simple 1megohm switched attenuator for say 10, 100, 1000V levels is fine for audio. Clamping the PC input using a diode to suitable dc voltage is likely to be better than the simple zener I use - as the zener 'leaks'. You can also set up a simple preamp attenuator diy (eg. Electronics Australia, August 1998).
Absolute accuracy is usually not a concern, nor is response well above 20kHz. You can make a higher impedance divider - a good idea for valve circuit checking. The software can usually pre-calibrate your probe circuit for a flat frequency response.
I've found a simple 1megohm switched attenuator for say 10, 100, 1000V levels is fine for audio. Clamping the PC input using a diode to suitable dc voltage is likely to be better than the simple zener I use - as the zener 'leaks'. You can also set up a simple preamp attenuator diy (eg. Electronics Australia, August 1998).
Absolute accuracy is usually not a concern, nor is response well above 20kHz. You can make a higher impedance divider - a good idea for valve circuit checking. The software can usually pre-calibrate your probe circuit for a flat frequency response.
I like this idea cheap 18 bit resolution. - propably a typical .7V diode clamp across the adc input would work well to protect things. But really analysing just the output with a soundcard and audiotester tells the story and you can deduce modifications/fixes from there. I have often wondered if there is anon-shareware (professional) Audiotester like program without all anoying the crashing.
But really what people need a scope for is chasing oscillations and HF peaks, so need a high bandwidth more than resolution. And most of us hobbiest don't have room or money for a big 200 mhz scope, the appeal of those small $300 USB 200 mhz scopes is there if they really did work. I know they are looked down upon here but I have often been tempted. One day I think they could be a real tool but as mentioned the 100x probe is never verifiable compatible and their actual bandwidth is questionable. Perhaps in a few years the technology in these little cheapos will be worth buying? For simple rf sweeps to find peaks ?
Interesting so good brickwall above audio and if no oscillation should be no DC after rectification. A soundcard and the right software (which would have a filter with the ADC) may even show the DC after rectification as an DC offset. I've never heard of this technique but it is much appreciated.
Which ADC/DAC do you use with yours? I have the one they recommended, but the square wave output shows a lot of ringing. I also don't know the bandwidth of the device.
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