To simulate, I have 1.5 volt battery where the solar cell .5 volt at 500 mA. where solar panel in bright sunlight would be. This can directly charge 9 volt NICd battery at about 4 milliamps. Ground can be positive or negative, your choice.
Germanium transistors (NTE102 or ECG102 PNP) work with the low voltage from .5 volt, 500 milliamp solar cell. Both audio transformers are 8 ohm secondary with 1200 ohm primary with the 8 ohm winding on bottom to boost voltage to output.
Two diodes below 8 ohm windings are 1N4148's, Four bridge diodes are 1N4002's. The 100 uf capacitor at output is rated 25 WVDC.
Voltage regulator can be added to output if better regulation is needed.
