Re: B7971 6 digit clocks
- --- In email@example.com, John Rehwinkel <jrehwin@...> wrote:
>That's more what I was thinking of. A gps like the one mentioned creates a drain of 45mA, the zigbee radio adds another 10mA.
> The other is to use a smaller, cheaper solar cell, along with a supercap and some control circuitry to store up power until there's enough, then fire up the GPS until it gets a lock, then fire up the transmitter and send a few bursts, then shut down again.
> - John
The gps gets a lock in 30 seconds and the radio only needs to turn on for 1 second to transfer the data and receive confirmation. That is less than 1mAh of battery capacity. If that happens every 4 hours then a supply capable of producing 0.25mAh is required, which even a small 5mA solar panel could provide (or two in series to produce a high output voltage on dull days)
A small rechargeable lithium cell for power storage and an LDO regulator to convert the voltage to charge it would probably work 'well enough'.