The XR 2206 data sheet is here:
This device is available at Jameco for $3.59 and has a frequency
capability to 1 mHz with high stability and generates sine square and
triangle waves. It is available at other places as well since Jameco
has it.
Another device is the ICL8038 which is useful to a little over 100 kHz
and it is available at BG Micro for $4.95 and possible elsewhere as well.
These two alternatives are likely available at numerous other places
as well.
The MAX032 is listed as several surplus inventory places but may be at
high prices from such sources... I could not find a "friendly
supplier" for the MAX038.
The XR 2206 seems the better substitute for the MAX038. It would take
a little study of the data sheet to select component values and
determine configuration for the ESR meter but should be no problem
[and the power supply voltages are the same].
