This two-transistor circuit is from a December 1964 Radio Electronics. Modern transistors can be tested. The headphone must be high impedance or crystal with a 2k2 resistor in parallel.
Linear Technology (www.linear.com) has in its component line the LT3518, recently launched, which...
This TTL circuit was obtained in a 1985 Italian magazine, but it can be easily implemented, as the...
This circuit simulates lightning using a small white lux type fluorescent lamp. The circuit is...