I always liked the battery backup in Dec 1994 and repeated/clarified in Oct 95 Wireless world which was
a voltage doubling rectifier (cascaded type (so no floating generator needed) ) clamped to 27V followed by a LM2575 step down regulator to 6V (which trickle charged 4 ni-cds for backup when stopped. The LM2575 was held off until rectifier output capacitor had reached a bit more than 20V DC.
.....
which appealed to me because the designer claimed that operating at the higher voltage of 30 Volt-ish (and less hub current) compensated for the solid state losses by reducing I2R losses at the dynamo coils ( a 15% efficient union 6701). He seemed to imply that his ni-cds never needed topped up.
I never built the circuit (at the time of Halogen bulbs) because at the time I thought a switcher would not work on stripboard ) and then LEDs arrived. But when I mention it in the context of LED lamp drivers the response seems underwhelming....
a voltage doubling rectifier (cascaded type (so no floating generator needed) ) clamped to 27V followed by a LM2575 step down regulator to 6V (which trickle charged 4 ni-cds for backup when stopped. The LM2575 was held off until rectifier output capacitor had reached a bit more than 20V DC.
.....
which appealed to me because the designer claimed that operating at the higher voltage of 30 Volt-ish (and less hub current) compensated for the solid state losses by reducing I2R losses at the dynamo coils ( a 15% efficient union 6701). He seemed to imply that his ni-cds never needed topped up.
I never built the circuit (at the time of Halogen bulbs) because at the time I thought a switcher would not work on stripboard ) and then LEDs arrived. But when I mention it in the context of LED lamp drivers the response seems underwhelming....