Other Parts Discussed in Thread: LOG104
Dear Sirs,
I've got an idea of improving an existing electronic part: Log104, a precision logarithmic amplifier from Burr-Brown. I came to Log104 while searching for an exponential (or antilog) converter needed to condition a sensor response. It looks like no manufacturer offers such converters today.
Log and antilog converters use the same components, only connections are different. Log104 has two free pins and I think they could be used to add antilog functionality to the part. Modification is very simple: cut the internal connection between the base of transistor Q1 and the common point of resistors R1- R2; then connect the base of Q1 to pin 2 of the chip and the common point of R1-R2 to pin 7.
To use Log104 as a log amplifier, connect pins 2 and 7 externally.
To use Log104 as an antilog amplifier, apply input voltage through a voltage divider including a temperature-compensating resistor to pin 2; connect a feedback resistor between pins 3 and 8; leave pin 7 open.
I'd be glad if designers can consider the idea and let me know what they think. The idea may not be applicable to the existing part as it needs to cut an internal connection, but can be useful for future designs.
Thank you,
Jordan
