This circuit was obtained in a magazine for radio amateurs 73 of the 90s. The circuit is based on the XR2206, which is not a component found easily today.
This Schmitt trigger in current mode for frequencies up to 50 MHz was found in a 1969 Motorola manual....
VR can be from 50 to 220k it is recommended to connect a 100-ohm resistor in series. The lamp may...
This circuit was published in a 1977 English magazine, but remains current, since we can assemble it...