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Basic Electronics Skills for Robotics
Getting Started with Robots
3D Printing Class
I'm sorry - I said that wrong. I measured a slope from 5V towards 0V on the PWM pin, NOT the base pin. So I measured voltage going BACK to the Arduino.The successful low-side switch configurations I've seen all used a 2-wire motor or device. Since the servo is a 3-wire device, could that be the difference?
The third one is the Lithium battery charging module. Part number 10 in the list.
In discussing this with a friend who has an electrical background, he thought the diode would interfere with the PWM signal. That'd be something to try to see if it's true.
I tried more than one NPN and got the same results. I don't think it was a bad transistor however, as I wasn't getting voltage on the emitter pin - I was able to measure voltage (decreasing over time) on the base pin. As in, it started at 5V during execution, and while sleeping slowly crept towards 0V over the course of several seconds. I didn't like that, couldn't explain it, but it felt wrong. Was able to eliminate that issue using the PNP high-side.
Thanks! Everything done in this instructable (well, the previous one) was a new skill for me, minus the software. You are correct regarding the PNP and NPN configurations I tried. I did try an NPN in an emitter follower circuit, but everything I read seemed to indicate it was rare. Not knowing why it was rare, I figured I'd stay with a more traditional use of the transistors. I didn't measure down to the sub-mA level when I tried it, sadly. At the mA level, it was the same current, but what you say makes sense - it seems like it should be lower.I've looked at some of your other projects, I like what you've done with the attinys. Seems like a good way to reduce current even further.
If you do that, I'd love to see it, and hear what your sleep/idle current is. Part of the challenge of this was reducing the battery usage in order to handle several days of overcast. I don't have an ESP8266, so can't measure it. I should just go get one.
Smart BlindsView Instructable »
Thank you. I've only got a 2-second window to catch them in operation. I'll need to get up on the ladder and cover the sensor to make a video - maybe this weekend if I have time. On the next iteration I'll make a video while creating it (with instructions in mind this time!).
I haven't tried that yet - it was my understanding that a board like that would need to be running all the time, but I put the Arduino to sleep to save battery - not sure if the board would be able to wake it. I'll have to experiment with that or bluetooth on the next iteration.
Automated Solar Powered Hor...View Instructable »
SOLAR POWERED ARDUINO WEATHER STATION
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