Crystal variable oscillator (CB9506E)

Found in Radio Electronics from the 90s, this circuit can vary the frequency in small values around the crystal frequency.

RF Oscillator LM3909 (CB15924E)
The main feature of this RF oscillator that operates in the range of 100 to 800 kHz is its low...
Flashing Bicycle Backlight (CB17672E)
Many people currently use the bicycle as a means of transportation and leisure in large cities....
Crystal Radio (CB18578E)
In this radio the coil can be made with 70 + 30 turns of wire 28 to 32 in a cardboard or PVC tube...