If you are looking for a constant frequency generator that easy and inexpensive. Here are the transistor crystal oscillator circuit ideas. They may help you works finish. Since 30 years…
This is Crystal tester circuit using NPN transistors as main. LED1 is light up when a crystal is good and simple oscillator circuit works.
This is 60Hz calibration frequency standards for digital clock. As 50hz or 60hz frequency generator at TP 3.579MHZ. power supply 12V.Out put Frequency 60HZ [...]
ECG simulator circuit is very useful in the medical community. Such as experimental research - development of bio-medical image, using Digital IC as main [....]
This is a Simple IF signal generator circuit using CMOS IC CD4011 as oscillator -CD4040 as divider and crystal-3.579 MHz into output AM: frequency 455 KHz