HP 67 Battery charger not working - any alternatives

[ThomasF]

(04-08-2021 05:56 AM)Hans Brueggemann Wrote:  

(04-07-2021 07:22 PM)AndiGer Wrote:  Maybe something like taht?
http://davidreaton.com/hp-calculators/hp...-chargers/

that circuit with the LED looks odd. seems that emitter and collector of the transistor got accidentally swapped.

Hi Hans!

Yes, you are observant and probably right!
Compare with the drawing by Tony Duel:

https://www.hpmuseum.org/forum/attachment.php?aid=8320

That will probably explain why my breadboard charger doesn't finish charging ...

Thanks!

Best regards,
Thomas