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It just so happens to be the perfect battery to deliver almost unlimited power to the Reaper down to 0.025 ohms at 2880 watts. With such a powerful battery we could not just slap in just any chip, as nothing exists to handle this range of power. So we constructed a board from scratch that would redefine what a regulated lipo box mod is capable of. Our patent pending board consumes almost no power and delivers the full range of voltage from 0 to 8.4 Volts using our 555 PWM and recessed potentiometer. Integrated Mosfet is crucial to our design.
What's funny is I was considering an ATTiny5/10/13 or 85 based PWM board before I settled instead on a variation of a 555 for the Timer kit I'm making. But I've never given up on looking at other things. I went with small and modular as well as something people could hack for themselves or use for other things.But gratz on this board. The monitoring what the battery level is, I'm assuming you are using the ADC to measure the internal voltage reference so you can detect what the current voltage is as the battery drains?
Whats wild DIYfancy, EE forum poster Craighb swears by this board for doing displays with using another pcb, we did not vape over 30watts back when then. Who knew like the 555 just use it as a "switcher pwm" with high power fets. It wasn't even considered, ya it's uber fun/entertaining seeing old school chips kick'n butt.
@Visus The MOSFET is off the board on my design. The current the mod could handle is dependent on the MOSFET, battery and wire used. All the board really does is switch the MOSFET. It doesn't see any high current. It's around 30mA-40mA max when it's firing. Around 3mA at idle. @DIYFancyLights I'm using the 5v version of the MC33275 to power the Attiny85 and as the voltage reference. The tolerance is pretty tight at 1%(for an LDO) and the voltage divider resistors are both 0.1%. Normally on something like this I would use a proper voltage reference, but it's actually within those numbers, which aren't too bad at all for what it is. The internal voltage reference(1.1v on the Attiny85, I believe) is way too inaccurate. Try like +/- right under 10%. It's not meant to be a precision voltage reference.
Ha! I think we all know each other. I prefer IRLS3813 for my builds, but that's cool. The new verison I'll have out(working on it with someone else) will be using two of those on the board. Keep in mind Vgs ends up ~4.5v with my board, which is what those are optimized for, IIRC.
It's still relevant. It's all good.
I've seen them. They're cool.
http://electronicdesign.com/power/informed-analysis-picks-better-555-timer-drive-power-mosfetThe input capacitance of the IRF 4905 is typically 3500 pF. Using the well-known current-charging equation I = C dV/dt, we find that the gate charging and discharging current with a 12-V square wave is about 21 mA, twice the rated output of the CMOS 555. That explains the failures.The solution was simple. The timer chip was changed to a bipolar NE555 (rated for 200-mA sink and source current), an 82-? resistor was added to guarantee that the current would always be below 150 mA, and the switching frequency was reduced to 3 kHz to reduce the proportion of time spent “on the slope.” The resulting circuit performed more reliably, and the MOSFET did not even get warm.