---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 07/07/17: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:04 PM - Re: Re: IVO Prop current limiter (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 01:04:47 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: IVO Prop current limiter At 11:16 AM 7/6/2017, you wrote: > > > > This might be another opportunity for an open source > > project. Once you've finely tuned the code, we can > > poke it into chips for mounting on a dedicated > > ecb . . . have you considered solid-state > > switching as opposed to relay? > > >Bob, > >I'm open to any of your great ideas. >I had not considered a solid-state switch instead of a relay, >but that does sound like a good way to go. > >It would be nice to have this in a small package. >Right now, I have the Arduino (clone) board in an enclosure, >and the other components in the separate enclosure I had >been using for your original circuit. Yup . . . make it work on the bench then 'distill' it . . . Do I recall correctly that once you have 'golden code' in the silicon, the chip can be lifted out and dropped into an embedded controller with minimized peripherals? If I were stuffing this functionality into an 8-pin PIC chip, I would explore something like this . . . Emacs! Set up Q1/R2/Q3 as a classic, ultra-fast current limiter. Select R2 to target stall motor current limit. Current limit is approximately I(limit) = Vbe(Q3)/R1 Vbe(Q3) is about 0.6 volts. Hence, setting R1 at 0.1 ohms would get you a 6A current limit. I think we were shooting for 9A so R1 = 0.066 ohms. I would parallel a number of resistors on an ECB to achieve 66 milliohms. Q1 doubles as a motor controller turned OFF by clamping gate to ground with Q4. D8/D9/R10/C11/Z12 conditions the COMMAND SENSE signal to a discrete input. R5/C6 conditions a CURRENT LIMIT SENSE input to an analog input. Q4 is a software driven clamp to remove drive from Q1 during a LIMIT CURRENT shut down. The +12 source in schematic above can be BUS, a precision 5v source ie easily acquired for small uC chips with a circuit like this: Emacs! Smartware would read something like this: Power-up routine SETS a LIMIT LATCH which drives gate of Q4 HI. A rising edge on COMMAND SENSE clears the LIMIT LATCH which removes drive from gate of Q4. LIMIT SENSE is monitored for input greater than 0.5 volts for greater than 0.5 second. Any excursion below 0.5 volts resets the limit timer. If limit times out, then the LIMIT LATCH is SET, gate of Q4 goes HI and motor power is removed. This condition is sustained until next rising edge on COMMAND SENSE. It looks like the tiny Arduino products could piggy-back onto a board that hosts the peripheral components . . . but as long as you're making a board, you might explore the option of programming a chip in an Arduino development system for dropping into your target ECB. To the extend that any of this is useful, feel free to adopt or adapt as you see fit. Bob . . . ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.