Ucurrent

[billg]

I was thinking of getting a u Current for testing both flame rectification (uA) and ionization current (nA).  My question is that since half of the cycle is going to be in flame rectification mode and the other half ionization, how will it react to over range in nA setting ?

[TriodeTiger]

If the battery voltage is increased to 5.5V (maximum) the range for nA will become ~0-2250nA, as the highest value (1mV/xyz) would be at 2.25V, because of the virtual ground (?) - so it can't go much over-range, but if it's below 2.2uA..

[MLXXXp]

If you go out of range, the output voltage will pin at close to + or - half the supply voltage.

If you're wondering about how safe it is to go over-range, here's a post with some (very conservative) calculations I did a while back:
https://www.eevblog.com/forum/crowd-funded-projects/current-gold-on-kickstarter/msg375819/#msg375819

If the uCurrent is always on, or you add some protection diodes for power off, the safe ranges increase:
https://www.eevblog.com/forum/crowd-funded-projects/current-gold-on-kickstarter/msg376311/#msg376311

The protection diodes, and modifications that I made to shift the virtual ground, which may be useful for your situation, are described here:
https://www.eevblog.com/forum/crowd-funded-projects/current-gold-on-kickstarter/msg448208/#msg448208

[billg]

Thanks for the replies,  MLXXXp this is just the what I needed:)