CM Harringtonoctothorpe@mastodon.online
Jul 29, 2026, 5:05 PM@paulrickards I mean… it’s probably not still too late to just pop an ND filter over the lens, and that way you can use either pack.
Replies
paulrickardspaulrickards@mastodon.socialJul 29, 2026, 5:08 PM@octothorpe The ND filter isn't needed now that the capacitor has been changed.The missing battery from i-Type film packs that is the road block.
I'll probably iterate some more until I find a circuit that can tolerate powering the motor.
Steve Herseyn1xnx@tilde.zoneJul 29, 2026, 5:26 PM@paulrickards @octothorpe
I wonder if adding a fair-sized capacitor across the power input to the camera would absorb the surge current and prevent shutdown.
Of course, too LARGE a capacitor would impose a turn-on load that could also trigger shutdown.- paulrickardspaulrickards@mastodon.socialJul 29, 2026, 5:57 PM
@n1xnx @octothorpe Possibly! Any guidance on a capacitor value to try? It's a 6V supply (fresh pack measures 6.4V).
- Steve Herseyn1xnx@tilde.zoneJul 29, 2026, 6:06 PM
@paulrickards @octothorpe
Start out with, say, 10 uF and go up from there to 47, then 100, then 470. Use a working voltage rating of 12V or higher. If none of those help, you probably really do need a higher-rated power converter.I've played with those Polapulse batteries in the past; (ISTR that for a while they were sold separately), and it's notable that their shape (flat, WIDE electrodes) gives them an inherently low internal resistance, which is important when powering the camera's motor startup surge. I recall reading about that in the literature back in the day.
- paulrickardspaulrickards@mastodon.socialJul 31, 2026, 9:59 PM
@n1xnx @octothorpe Thanks for this! I tried adding some caps to the board but it still shuts down as soon as the motor is connected. When I tried the 470uF, it struggled to even start up, and would “brown out” at lower voltages. Switching it off and on it would eventually reach the target voltage. But alas, it still shut down too. These charge/boost circuits appear to be not so great. Bummer too, the size is great and has a trim pot to adjust the voltage. Oh well.
- Steve Herseyn1xnx@tilde.zoneJul 31, 2026, 11:48 PM
@paulrickards @octothorpe
The next thing to try would be adding a second Li-ion cell to boost the voltage, and using a linear regulator. The power consumption is low enough that the efficiency loss of a linear regulator is insignificant, and 3A linear regulators are not too large. There are ways to adjust the output voltage of the regulator to match the battery you are replacing. You'll want a separate power switch to disconnect the battery from the linear regulator when this unit is not in user.