Quote Originally Posted by lerameur View Post
and lastly,

i want to use a 9v battery to power the system. I want to add a led to signal when the battery need to be changed. would you know at what voltage this would be ?
Watch those sales you can get a solar yard light for < $8.00 US complete with rechargeable batteries you would have solar panel, batteries, housing and an LED to flash!, you would have to settle for 3 volts though.