HP Forum Archive 21

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HP charger 82002c for handheld calculators Message #1 Posted by Dave Burson on 19 May 2013, 1:42 a.m. I was gifted with a box of small transformers and among them was a 82002C charger which can be used with the HP-35, 45, etc. This has a 3 pin output and meters a nominal 5 VDC between center and right pin and nominal -17 VDC from center to left pin. The 5 volt side makes sense but is the other voltage an indication of a bad circuit? The label says that the output is 50 MA at 4.2 VDC and 150 MA at 4 VDC. Obviously I'm in over my head here, so any thoughts would be appreciated. I'm only pursuing this because these things seem to have some value. Thanks, Dave

Re: HP charger 82002c for handheld calculators Message #2 Posted by Gerson W. Barbosa on 19 May 2013, 1:57 a.m., in response to message #1 by Dave Burson Quote: This has a 3 pin output and meters a nominal 5 VDC between center and right pin and nominal -17 VDC from center to left pin. The 5 volt side makes sense but is the other voltage an indication of a bad circuit? Please take a look at HP Battery Information, in this museum. Quoting from the linked page: "The battery charger circuit is current limited and will typically read much higher than 4.2 V without a load." HTH Gerson P.S.: Classic Charger Schematic Edited: 19 May 2013, 2:14 a.m.

Re: HP charger 82002c for handheld calculators Message #3 Posted by Dave Burson on 19 May 2013, 12:51 p.m., in response to message #2 by Gerson W. Barbosa Thank you Gerson, I didn't expect such an on-spot answer. It looked like those paragraphs were written just for me. Much appreciated! (BTW, I fathered only girls, but had considered that if I had a son I might have named him either Gerson or Thurston. I thought Gerson Burson would have a memorable ring.) Best regards, Dave

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