Used vintage analog transistor sine wave sweep audio oscillator (AC version), made in West Germany in the 1960s or in early 1970s by Hewlett Packard Böblingen, in my possession and in occasional studio use since the mid-1990s (bought used as is). Apart from the obvious and intended testing purposes, it’s also great as a uniquely sounding experimental live instrument. Frequency range 5 Hz to 500 kHz, 115V/230V switch, DC balance control. Connectors: 2× output 600 Ω, max. amplitude 10 mW, 1× ground (3 thumbscrews). Dimensions: 130 × 155 × 205 mm, weight 2.5 kg. Included: power cable with Swiss plug (removable). More info: radiomuseum.org/hp_oscillator_204b (German), hpmemoryproject.org/hp204b (English), prc68.com/HP204 (English), hparchive.com/HP-204B-Manual (PDF, English)
Selling price: CHF 99.– or nearest offer, plus shipping. (Original retail price in Germany: DM 550.–)