As already pointed out on the parent page, this is a small footprint 50% duty cycle square wave oscillator with variable frequency from 10kHz to 30MHz. The frequency range can be extended to 1kHz by using 1M instead of 100k for R6.
Supply voltage is 5V (5.5V max); lower voltages (e.g. 3.3V) can also be used but will limit the maximum frequency to values significantly below 30MHz.
The sheet presented here drives the square wave directly into 50 Ohm; the output stage uses 5 parallel 74AC04 CMOS inverters which sums up to a total of 120mA max. (Some people may shout at me here because I did not use parallelizing resistors between the gate outputs. Oh well, but it works fine for me this way...)