gunrunnerjohn posted:Well, I did some bench testing with real TMCC components, and in conventional and command, the battery replacement worked great! Other than waiting a minute or so from a cold power on to get the cap charged, I could operate and do frequently reversals in conventional mode with no dropped sounds, even at the lowest power that the R2LC and motor driver would keep running. I kept nudging the power down until the drive dropped out, still had the battery charging away, so it works at a lower voltage than any of the other electronics.
I think my one remaining issue is the scheme I used to limit the voltage to the Super-Cap isn't sufficient. The LM06 and the silicon diode don't drop enough at low currents to keep the voltage below the max for the caps. I suspect I'll have to go to the LM317 and tune the output to around 5.5-5.6 volts to insure we don't push the supercaps over the 5V rating. I was trying to save having to add a couple more components, but obviously that's probably going to be necessary. If I let it sit and charge for long enough, I get up to about 5.45V on the supercap. Since the cap is really two 2.7V caps in series in the package, that's too much. Given that we seem to have plenty of capacity for the intended purpose, I'm thinking I'll try to limit the supercap voltage to around 5V max. That still gives me the full 8-9 second shutdown, and the cap has more to give before the switcher shuts down.
Just talking, but what would happen if you proportioned the voltage divider to use a little more current? You are down in the microamp range! Would 5 - 10 mA hold the voltage down adequately?
Thinking about what you could do without adding parts.
