This circuit with RIAA equalization is from 1985 US documentation. The circuit has a flat response of 150 Hz to 40 kHz. The power supply must be symmetrical.
This circuit for currents from 500 mA to 1.5 A was found on a Ham Radio from the 90s. R4...
Found in a PE Hobbyst in 1991, this 13.6 V power supply with a 2 A current is suitable for supply...
This circuit generates low-frequency sinusoidal signals. The variable capacitor is dual and the...