We found this configuration in a 1990 Poptronics. The circuit can be powered by voltages between 6 and 15 V, changing the resistors in series with the LED. The frequency is set at R7.
This circuit excites an LED, which will flash at a frequency adjusted by the trimpot. The other...
This circuit, found in a publication from the 1970s, produces a 1 Hz sinusoidal signal....
In this circuit, the output voltage is Vxx plus the zener voltage. The circuit is from the SGS...