The Signetics NE-602AN device is a double-balanced modulator (DBM) and an oscillator-integrated circuit. Normally, it is used as the RF front end of radio receivers, but if the DBM is unbalanced by placing a 10-kilohm resistor from the RF input (pin 1) to ground, it will function as an oscillator that produces about 500 mV of output signal.

The NE-602AN Colpitts oscillator circuit is shown below. Three capacitors (C2, C4, and C5) are used in this circuit, rather than two, because of a need for dc blocking. These capacitors should be equal to each other, and have a value on the order of 2400 pF/F MHz. The inductor should have an approximate value of 7 uH/F MHz. The tuning capacitor, C3, should have a value that will resonate with the selected inductor:

C3=1/(4 x (3.14)² x f² x L1)

C2=C4=C5= 2400pf/ f _MHZ

L1=7uH/ f _MHZ

For example, a 5000 kHz (5 MHz) oscillator should have network capacitors of 2400 pF/5 MHz, or 480 pF (use 470 pF standard value capacitors). The inductor should be 1.4 uH. To resonate with the 1.4 uH inductor requires 723 pF. But 470 pF/2, or 236 pF, are already in the circuit because of the series network C5/C4. Thus, a variable capacitor (C3) of 723 pF - 236 pF, or 487 pF is used

An NE-603AN Hartley oscillator is shown below. This circuit is identified by the tapped coil in the LC network. The value of the inductor is about 10 uH/F MHz, and is tapped from 1/4 to 1/2 of the way from the ground end. The capacitor needs to resonate at the desired frequency. For our 5 MHz example, an inductor of 2 uH is used.