We found this circuit in a 1994 National Semiconductor technical documentation. The circuit can be adapted to operate with more modern equivalent operational amplifiers.
Indicated for scanning circuit applications, we found this generator in a Radio Electronics from the 80s....
The circuit shown in figure 3 uses a programmable unijunction transistor (PUT) of the BRY39 type...
This is the version of the previous circuit with a locking system. The supply voltage is according to...