We found this circuit in the November 1992 Radio Electronics magazine. The circuit uses an LDR as a sensor and the transistor can be any general-purpose transistor.
The frequency of the signal produced by this circuit depends on the temperature of the diode used...
This small transistor radio was published in Radio Electronics magazine in November 1957. The...
This simple adjustable source uses a PNP transistor that can be the BD136 for even slightly higher...