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by theitguyfromny
Wed Feb 13, 2019 3:26 pm
Forum: Beginners
Topic: Power Supply for multiple 12V devices
Replies: 5
Views: 177

Re: Power Supply for multiple 12V devices

The FET toggling is definitely another whole thread. (I have one somewhere). I didn't really understand why I needed the "source ping PIN", either, but in the end, that's what's working perfect in my case. (I suppose it has to do with exactly how I need to hold the solenoid at times either on or off...
by theitguyfromny
Wed Feb 13, 2019 12:37 pm
Forum: Beginners
Topic: Power Supply for multiple 12V devices
Replies: 5
Views: 177

Re: Power Supply for multiple 12V devices

Thank you both. I'm almost ready to buy this... But ... in the picture, the output wires seem awfully thin I think I see (up close) that white wire is 18AWG, rated 10A/600V, so any insulation melting problems would def. be a return (defective product), but I do understand what you're saying. I'm alw...
by theitguyfromny
Tue Feb 12, 2019 10:43 pm
Forum: Beginners
Topic: Power Supply for multiple 12V devices
Replies: 5
Views: 177

Power Supply for multiple 12V devices

I know there's other threads similar to this, but not exactly the same. I want to run several solenoids (3 right now for testing, but many more down the road, even near 100)...from RPi. I have 1 solenoid running now with a 12V 2A power supply and a FET. Works perfect. Without going into details abou...
by theitguyfromny
Fri Feb 08, 2019 1:15 am
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

I'll take a few more "almost end of thread pics" and see if anyone sees anything else obviously wrong/missing/dangerous. The FET was getting real hot before (too hot to touch), but not w/ the set up I have now, I don'think. I'll have to check again. I think it's because I was keeping the solenoid in...
by theitguyfromny
Thu Feb 07, 2019 9:20 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

OMG! I got it! So I went back to this video: https://www.youtube.com/watch?v=BICMGcNw55g&t=87s Guy touches the gate with finger (sending some minor "human" voltage) which activates it ("closes" it) *** To open the gate back up **, he has to touch both the gate AND THE SOURCE with his fingers...which...
by theitguyfromny
Thu Feb 07, 2019 5:08 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

I see you have something (small orange box-ish thing...a Mylar capacitor??) on the gate of the NPN connected to your motor. I'm guessing w/o it, you'd have the same problem as me. Although a stepper has different electrical input properties than a solenoid, of course. (I have one of those and actual...
by theitguyfromny
Thu Feb 07, 2019 12:25 am
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

I only sort-of get it. If I connect the 5V pin at all, it will give constant voltage; I want to CONTROL the voltage, only sending through BPM mode in software here and there. So, would I add a diode in-line with the wire to GPIO 40? The question still is, 2 grounds?...going to the same place? I feel...
by theitguyfromny
Wed Feb 06, 2019 3:27 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

I don't want to break another RPi ...or maybe it wasn't even me. My new Rpi should be here sometime today...and I'm already thinking (of course), did I break it or do they sometimes just go bad (defect)? The last time it was fine, I was touching the gate wire (literally, the resistor end directly u...
by theitguyfromny
Mon Feb 04, 2019 11:36 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

Another project delay now. Pretty sure I blew out the entire RPi. When I left for my appt, it worked fine. I unplugged everything, because I'm careful like that. Came back, plugged it in and...nothing. No Wifi apparently, no monitor, no yellow activity light, SD Card contents seem as fine as I'd exp...
by theitguyfromny
Mon Feb 04, 2019 7:58 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

Ok. Thanks so much! Had to walk away for about 2 hrs (appt), but super-excited to get back and finish this up... I obviously have to figure out hardware (your reply 1) before the Python stuff, but I didn't know about that PCM mode change. Not sure exactly where you're saying to move the resistor, th...
by theitguyfromny
Mon Feb 04, 2019 6:52 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

Here's a link to photo of labeled set-up.

https://drive.google.com/file/d/1adAPr8 ... sp=sharing

Hope that works (was too large file size to post )

Again, right now, it works perfect...once. Then I have to unplug it, wait a bit, plug it back it again, works again...once.
by theitguyfromny
Mon Feb 04, 2019 6:39 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

I don't know the voltmeter, but doesn't the decimal location of that # just have to do with the setting on the voltmeter? (20 versus 200, vs, 1000, etc)?
multimeter.jpg
multimeter.jpg (244.94 KiB) Viewed 1404 times
by theitguyfromny
Mon Feb 04, 2019 6:21 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

Works as you describe.

NOT connected: About .20 (voltmeter set to DCV 20)
CONNECTED: .10/.09
by theitguyfromny
Mon Feb 04, 2019 4:32 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

So sorry about the NEG to GPIO thing. If you look back, I'm not sure anyone ever said that, all the triple-confirming I did... First: Here's the photo: FET.jpg The yellow wire, the GATE, I had connected to the GPIO. Your test just now had me tapping it on the 3.3V on the RPi. The middle white wire, ...
by theitguyfromny
Mon Feb 04, 2019 3:55 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

OK, so first test you suggest: I disconnected the gate wire from the GPIO pin (the ONLY pin I had connected) and tapped it - instead - against the always-on 3.3V GPIO pin...and still got no activity. I think what I'm missing is the GND on the GPIO. Don't I need to connect 2 pins to the RPi? a POS AN...
by theitguyfromny
Mon Feb 04, 2019 1:15 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

Finally got a chance to test this morning (everyone back to work now, Mu haha) and...I guess the good news is all my connections are solid. Bad news is I can't get the solenoid to power up. Just for a test, I've tapped the wires directly to the solenoid and it clicks over (just to make sure there's ...
by theitguyfromny
Sun Feb 03, 2019 5:58 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

Thanks so much. So, right now I have: -------------- | | | | | | | | ------------ | | | | | | | | | (G) (D) (S) G is Gate: goes to GPIO pin (P.S....that is set to OUT mode) with a 1K resistor in-line (resistors are NOT direction-specific) D is Drain: goes to solenoid S is source: goes to negative of...
by theitguyfromny
Sat Feb 02, 2019 8:58 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Re: Resistors and MOSFETs and fire-prevention, oh my

Thanks. The question, though, is what size resistor.

As far as a diode, same q: where, and...what size?
by theitguyfromny
Sat Feb 02, 2019 2:36 pm
Forum: Beginners
Topic: Resistors and MOSFETs and fire-prevention, oh my
Replies: 156
Views: 8130

Resistors and MOSFETs and fire-prevention, oh my

* Note: This is not a problem, it's a question beforehand so I don't have a problem. I have: 1) a RPi 3B+ 2) a RFP30N06LE 30A 60V N-Channel Power Mosfet . I bought it from Amazon but I think this is a valid spec sheet...https://www.sparkfun.com/datasheets/Components/General/RFP30N06LE.pdf 3) a 1/4in...
by theitguyfromny
Sat Jan 12, 2019 9:23 pm
Forum: HATs and other add-ons
Topic: Air Pressure Regulator/Solenoid
Replies: 4
Views: 517

Re: Air Pressure Regulator/Solenoid

I may look into the whole squeezing the line thing a bit more. Since this is not a scientific or medical sort of project, I don't have to be exact (I'm not really measuring anything). If I had two servos working like a thumb and index finger together, they could compress the line together to minorly...
by theitguyfromny
Fri Jan 11, 2019 4:53 pm
Forum: HATs and other add-ons
Topic: Air Pressure Regulator/Solenoid
Replies: 4
Views: 517

Air Pressure Regulator/Solenoid

First: I am new to all this. A programmer for many years, but new to RPi and "physical computing". That said, I am looking to only-very-minorly regulate the flow of air (through a fish tank sized small vinyl air hose) using RPi/GPIO. I know of solenoids, but as far as I know they strictly are all-th...

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