Forum Rule: Always post complete source code & details to reproduce any issue!
Results 1 to 4 of 4

Thread: Electronics question. Why this blow up. No teensys involved

  1. #1
    Senior Member
    Join Date
    Feb 2016
    Location
    Australia
    Posts
    204

    Electronics question. Why this blow up. No teensys involved

    Hello.
    I have been playing around with stroboscopic effect and though I would make myself a big strobe light.
    I ordered a few bits and thought this would work:
    Click image for larger version. 

Name:	mosCirc.PNG 
Views:	18 
Size:	105.3 KB 
ID:	15308

    This turns on the led panel fine if I pull the signal wirre high to 12Vdc, and turns off if I disconnect the wire.

    I then hooked up a cheap arduino nano and an adafruit clone 16ch pwm board running at 1.7khz which slowly sweeps duty cycle from 0-100%.
    problem is my lamp lit up for a second, then the pwm board let out some smoke.

    Nano is no longer detected by windows, and pwm board does not work.
    I have spares hooked up and ready for round 2 but I'm not really sure what went wrong.

    I should say I'm not great at electronics so probably something simple that I don't understand.

    Any Ideas let me know.
    Thanks.

    Click image for larger version. 

Name:	7C946E54-7114-4658-9B21-AA661EB59C49.jpg 
Views:	14 
Size:	134.8 KB 
ID:	15311

    12.6vdc supply powers led driver circuit above and also goes to arduino nano vin and gnd pins.
    Single wire from PWM signal was connected to my mosfet driver trigger. Wire length was about 20cm I suppose if that is relevant.

    Click image for larger version. 

Name:	m1.PNG 
Views:	8 
Size:	266.7 KB 
ID:	15312Click image for larger version. 

Name:	m2.PNG 
Views:	4 
Size:	255.8 KB 
ID:	15313
    Last edited by Gibbedy; 12-07-2018 at 03:50 PM.

  2. #2
    Senior Member
    Join Date
    Feb 2016
    Location
    Australia
    Posts
    204
    Killed another nano and pwm pca9685 board.
    My nanos have regulators marked 1117-5 they are going up in smoke.

    I used a pololu 5v 500ma buck converter board and it is working so far.

    Thats what I'll go with at this point.
    Note last nano that failed I only had nano and pwm board connected.

    Vcc and V+ are powered from arduino regulator. I believe it should consume very little power as I'm not driving anything but a mosfet driver but perhaps there is some other consideration. Here's my attempt to show what I did here. Click image for larger version. 

Name:	I2C NANO BOARD_bb.jpg 
Views:	9 
Size:	87.4 KB 
ID:	15314 incoming black gnd should have gone to gnd rail not as shown in pic.

  3. #3
    Senior Member
    Join Date
    Apr 2017
    Posts
    136
    What PWM frequency are you driving the mosfet (Arduino through U1) with 1.7kHz, how are you getting that? I see no timer divisor capable of getting that frequency. Maybe add a current limiter between arduino and input on U1--maybe a 100 ohm will do.

  4. #4
    Senior Member
    Join Date
    Feb 2016
    Location
    Australia
    Posts
    204
    Iím using an Adafruit (clone) pca9685 breakout board just because I have it to add a buffer between an expensive teensy and the mosfet driver which I donít fully understand. Iím using a nano here to test things out and glad I did.

    I was thinking of adding a resistor as you say but while I was setting up scope on nano with only pen board connected I smoked it so Iím doing something wrong with Pam board or my nanos have fake 1117-5 regulators.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •