[sdiy] Adapting exponential convertor for single supply

[Tom Wiltshire]

Hi All,

What’s the simplest way to adapt this exponential convertor for a single supply (0-9V)?

http://imgur.com/ZhixiC7

Could I use a simple midpoint bias to act as the ground and expect it to work? It feels wrong, although I don’t know why.
Bumping the “grounds” up to a useful level with diodes feels better somehow, more like is done in this schematic:

https://hackadaycom.files.wordpress.com/2015/09/two_transistors_expo-sch.png

What would you recommend?

Thanks,
Tom

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