My vintage probe-style multimeter started playing up and I decided it was time to replace it.
I got a new one from Jaycar - QM-1498.
It has one slide switch and four push-buttons on it. One of the buttons is marked "LI". As far as I can fathom, LI stands for "Low Impedance", and it appears that pressing this button while in AC or DC volt mode connects an extra resistor across the probes to reduce the normal 10M input resistance to 400K. The leaflet says that this "may check the tangency state of the crunode".
Wikipedia tells me that a crunode is a point on a self-intersecting curve where there are two distinct tangents. However this does not help me to understand how to measure the tangency state.
Actually I don't even know when or why I would want to do that, so I'm not sure why a relatively inexpensive multimeter would have a special button to help me do it.
Can anybody enlighten me?
Andy Wood firstname.lastname@example.org