I would like to study a bit circuits that include inductive coils, like LC, LR etc. But I understand that inductors can easily produce a spike of 1,000V and I am a bit afraid to ruin an expensive instrument like oscilloscope. Usually, components on a breadboard are quite flimsy and if one of them accidentally looses contact I'll get spike even without knowing what caused it.
I do not really care about burning out few capacitors or even ICs, but wouldn't like to ruin oscilloscope. How can I study LC circuit by 100% making sure oscilloscope is protected from high voltage spikes?
You could add protection or snubber circuit across the inductor (for instance back-to-back zener
diodes, aka TVS diodes, can limit voltage excursions).
Snubber circuits are RC networks designed to both limit the voltage spike from an inductor
and limit the "ringing" of any LC resonance (using just a capacitor would usually lead
to extensive ringing).
When dealing with relays motors etc a simple freewheel diode is used to prevent back EMF
spike on switch-off.
Most scope probes have a "x10" setting (which divides the voltage by 10) - always choose this
if high voltages may be present since there will then be 9Mohms in series with your 'scopes
input(s).
I didn't know about these snubber circuits. Gona look them up.
After writing the post, I came up with idea to simply put an potentiometer, in a mega Ohm range, in parallel with coil and than attach scope probe to the lower division. That way I can pre-attenuate any spike by factor I choose, like 100 or even 1,000. Plus, I can put fly-back diode in series with pot, just to protect scope further from voltage reversal.
Actually, I still want to measure that spike, so I can be aware of it for future designs.
