Oscilloscopes - what specs to look for?
Bob : That's a plug in to a music production system. I don't think that's exactly what the OP was looking for. I think these are a little closer: https://listoffreeware.com/best-free-oscilloscope-software-windows/ |
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Small parasitic capacitance (even few pF) is enough to produce noise. Every scope I've ever used showed small high frequency noise when touching other circuit, even with probe shorted. It becomes a problem only when you need to look at mV level signals at high frequency, otherwise you can just limit bandwidth of the scope (or use two channels and take a difference). I agree that truly differential input should help, but even probe itself has slightly different inductance of both wires. If you don't have this problem - great. Perhaps you have better scope, I ever used. |
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Yes, there is alway some antenna, but there is a pronounced increase in noise when shorted probe touches the other circuit (shorted with wire loop or two-pin adapter). Battery powered scopes also show this to some extend, because of these tiny capacitances. Few pF becomes only few hundred ohm of reactive impedance at 100MHz frequency. |
