Isn't there a USB port? I suggest any USB charger.
Unfortunately this headset has no any kind of USB-connector. Charging is made with old fashion small DC-plug. BH 501 manual says " The headset is intended for use with the AC-3, AC-4, and DC-4 chargers".
With my BH 501 I'm using AC-4E which is labeled as DC-5V / 890mA.
So these headsets which require recharging don't come with the charger, or an adaptor? Very strange.
madbilly: sorry i don't remember. I bought mine almost 10 years ago. Do i use original charger or is it from some another Nokia accessorie / phone i can't say. I reckon BH-501 was sold at that time with some specific Nokia phone (5800 Music Express) which used compatible charger for both products.
Yes that's probably right. Your best chance is to go to a mobile phone repair shop, they'll probably have many chargers you can try until you find the right one.