RE(2): RE(2): matched expo source / sink idea

[Haible Juergen]

Dear Osamu,

Thanks for sharing this.
Placing the "npn diode" after the pnp emitter follower looks good !

I'm still puzzled how to drive a diode bridge with this configuration,
though.
Wouldn't driving a diode bridge mean the voltage of the source output
has to be higher than the voltage of the sink output ?

JH.

	>My senior at the high school developed similar circuit.  He tried
to
	>use this exponential converter for an original VCF based on diode
	>bridge and it worked.  (This VCF is similar to KORG MS50 VCF but
	>its diode bridge is current driven.)
	>The advantage is that PCB layout is easier than your circuit if you
	>use the Japanese pair transistors.
	>
	>To see this ascii drawing, please use fixed-width fonts.
	>
	>          ^ Vcc
	>          |
	>          R
	>          |            |Exp Current Out
	>          +-----+      |
	>       C   \    |     /  C
	>            \|  |   |/
	>      NPN    |--+---|   NPN
	>            /| B  B |\
	>       E   /          \  E
	>          |            |
	>          |            |
	>         /  E        E  \
	>     B |/                \| B
	>   >---|   PNP      PNP   |----+
	> CV    |\                /|    |
	>         \  C        C  /     GND
	>          |            |
	>          |            |Exp Current Out
	>          Vee
	>