This circuit was found in documentation from the 1970s. However, it can be implemented with modern transistors such as 2N2222 for Q1 and BF494 for Q2. The crystal depends on the desired frequency.
Static charges in objects Dan be detected by this sensitive electroscope. The meter indicates when the...
Found in Popular Electronics from the 90s, this circuit generates a 1 kHz signal. The coil is from an...
Using a 555, this configuration appears elsewhere on this site. This is from American...