This circuit was suggested by National Semiconductor and is present elsewhere on this site. The LM2575 is not very common today and should be mounted on a heatsink.
Found in a 1968 EEE, this circuit accepts frequencies from 1 to 1000 Hz and control voltages from 0.1 to...
This circuit has appeared several times on this site in different applications. This is from 1997...
This setting appears other times in this section from other sources. This is from an 80's American...