Hi Neil,
Good question. The PicoScope is quite tolerant of this. In fact, when I was first testing PicoScope for myself, I deliberately tried to break it by doing just that. I looked at a primary with a spike of over 400 volts. Well, years later, it's still working great.
Here is a small portion taken from the PicoScope Tips document included with each Master kit:
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Letting Out The SmokeDo not measure main supply voltage with the Pico. This is clearly stated in the documentation. Here is what the Pico boys had to say on this subject:
"The basic ADC212 as you know will measure to +20V. The overload protection is quoted at 100V, but in reality will take at least 200V. It will also withstand short spikes of higher duration (eg primary ignition, injectors etc without the x20 attenuator).
What will blow it up - secondary ignition will. Direct connection to mains 110 / 220V will as well. This is less to do with the voltage than with grounding. As with most scopes, the outer shell of the BNC is usually grounded (through the PC in our case). Connecting a lead across mains effectively connects neutral to earth - this is what damages the scope, not the high voltage. Our advice on mains is use a isolating differential scope probe -
http://www.picotech.com/accessories.html With the x20 adapter, you can measure up to 400V, transient spikes at least double this should be OK. "
Automotive voltages are not a problem provided you don't plug the secondary directly into it :-p
When powering the PicoScope on vehicle power, be certain of your connections and do not place a ground lead on a power source by accident. This will allow the power to find a path to ground through the PicoScope.
It is the users responsibility to take care when hooking up. Smoke can be expensive.
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We have had one in our group damaged by placing the BNC grounds accross a battery supply. I was able to put the smoke back in it, but was lucky there was not serious damage.
These issues are not peculiar to PicoScope. Placing the grounds of other scopes accross battery supplies kills them just as well. Also measuring mains with scopes that are plugged into the wall for a power supply will likely toast tham nicely.
Taking care with hook ups is essential with any such instrument. Occasionally forgetting the attenuator, while not advisable, will not likely hurt a thing. 8)