Mike Gasperi's RCX buffer
copyright: Mike Gasperi's sensor pages and
We first met this buffer with our (never-ending) gyroscope project. The LM324 is probably not the best choice for this task, but as Mike points out in his contributions to the remarkable book Extreme Mindstorms, the chip is cheap and easily available. Stef Mientki gives a pratical list of replacement op-amp chips depending on the prupose.
Here the results of our tests to find out the operating range. The buffer has a perfect linearity in that range.