Sony Walkman WM-BF65 - vintage and rare (in box) This model has an interesting new feature to the Walkman range: digital preset tuning. This was a real step forward over the mechanical system offered on the previous model, and was more stable, more versatile and easier to operate. The display could also show a clock and an alarm could be set that sounded a built-in buzzer at the chosen time. A special “double wet layer” capacitor was fitted inside. This unusual device behaved like a small rechargeable battery which drew power from the main batteries when they were in good condition and was capable of keeping the computer memory intact for about 10 minutes, plenty of time to fit new batteries. The WM-BF65 had a mono/stereo switch, which affected the FM radio only a must have for collectors