This circuit is one of many that the reader can find in this section for testing crystals. The circuit uses an indicator LED. Transistor Q1 determines the maximum crystal frequency that can be tested.
This two-channel DC volume control uses a transconductance operational amplifier. The transistors can be...
The CMOS 4046 integrated circuit is not very common today, consisting of a very efficient PLL for...
This is the project we have described, as found in a 1981 documentation. In the figure we show the...