Another possibility is an LED. The large bandgap leads to exceptionally low leakage. Breakdown voltage shouldn¡¯t be a problem (certainly better than a 3904¡¯s b-e Zener voltage). Capacitance is high but if you don¡¯t use a large one, you should be ok here.
Just shield the LED from light. It¡¯s photovoltaic.
Cheers
Tom
Sent from my iThing; please forgive the typos and brevity
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On May 25, 2022, at 10:45, Chris Smith <me@...> wrote:
?Got it. That's confirmed here as well. Doing too many tasks at the same time here to do any of them properly. I shall sit in the corner for a few mins with the dunce hat on!
By elimination of ideas, the JFET looks like the most sane solution now so it looks like I'll have to obtain one. I'll stick this DMM in the cupboard though until I've filled a Mouser basket.
Thanks for everyone's input on this; it was a valuable learning exercise for me :)
