At the DPRG RBNO last night, I worked out the basic design for my robot power supply with the help of a few other DPRG folks. The plan is to use 4 of the Maxwell 350F caps to store power from solar cells. (Someone was asking about the cost – the single unit price of the caps is $25). One hitch to using multiple ultracaps is that you have to dynamically balance the voltage between caps. To do this you need a simple circuit made of an op-amp and a couple of resisters. You need one balancer at each connection between caps so, for four caps in series, you need three balancers. John Drummond helped me track down the TLC25L4CN low-voltage op-amp. It works on as little as 1.4v (which equates to .7v per cap). That gives me an operating range of 2.5v to .7v per cap or 10v to 2.8v for the entire power supply. Once I get the parts and test it, I’ll post a schematic.

In other DPRG news, the DPRG mailing list upgrades have been completed. The list now has better spam and virus filters, email address munging, and a shiny new searchable list archive going all the way back to 1997.