3 ms·
> Hacks like this are a lot of fun to play with on the bench but don't design a circuit like this when you want something that "just works", has a reasonable li
by qb45 9y ago
> Hacks like this are a lot of fun to play with on the bench but don't design a circuit like this when you want something that "just works", has a reasonable life-time and certainly don't put a hack like this into production.
Dunno, do you think a constant rate PWM SMPS isn't enough to power a trivial load like LED and justifies the cost of adding a dedicated chip? LED forward voltage is well below absolute maximum for the RESET pin, peak current is limited by pulse time, looks good enough to my (amateur) eye.
- dom0 9y agoRSTDISABLE means that no in-circuit programming is possible any more and for re-flashing a parallel HV programmer is required; it's quite annoying for tinkering.
- qb45 9y agoYes, but this was about long term reliability so programming is of lesser concern.
- smoyer 9y agoI didn't mean that you shouldn't use a boost converter - back in the RS-232 days the Maxim max232 chip saved a tremendous number of parts (otherwise you needed a +/-12VDC power supply to drive the signal wires. The idea of the IC's Vcc following the coil's transient is a bit scary and I wouldn't design that into a system.
- qb45 9y agoI thought about using RESET of course. The Vcc thing is indeed bizarre and I wouldn't be confident that running logic circuits on a fast dV/dt power supply is a good idea.