Category: Data Collection

Chuck’s SDP Links

Posted on by CBMalloch

Articles especially pertinent to Senior Design Projects

Please share the problems you encounter!

U.Illinois Robotic Systems book – work in progress. In particular, this book already has nice sections on forward and reverse kinematics.

Switching Mains Power – not fully investigated yet. A place to start your investigation.

Sonoff S31 Mains Power Switches

Sonoff S40 Mains Power Switches

Adafruit Power Relay Module

Surface-mount soldering tutorial

“Ideal Diodes”: Protect Your Project from Reversed Polarity Power

Don’t use Nyquist as your only criterion for choosing a sampling rate

RP2040 resources from Cornell from their microprocessor design course ECE 4760

Wearable sensor for continuous analysis of sweat

Astrophotography and the new HD Raspberry Pi Camera

Raspberry Pi HD Camera for astrophotography

AstroPitography | Dr Adam Luke Baskerville

My DIY 8″ Telescope & Raspberry Pi HQ Camera

Astrophotography with Raspberry Pi HQ Camera and Celestron Astromaster 130 EQ

New Pi camera – any good for Astrophotography?

I2CWrapper – Using microcontrollers to translate I2C for non-I2C devices

System for digital signing of photographs

… and breaking the system for digital signing of photographs

Forest-deployed wildfire sensing and reporting system

New series of ATtiny µP eliminates requirement for dedicated pins

 

Blogs and Vlogs

 

Engineering, specifically EE, CompE

Eric Bogatin – Practical EE/CompE fundamentals and practical skills

Andreas Spiess – LoRa, low-power, sensor networks, ESP8266, ESP32

David Jones – EEVblog; instrumentation, troubleshooting, repair

Bil Herd – electrical engineer, designer at Commodore; CPLD, PLL

Moritz Klein – Audio electronics

Fran Blanche – FranLab; Apollo flight computer, DSKY, FranTone audio pedals

Big Clive – tear-downs

Ben Krasnow – Applied Science; including electronics; how he built his own electron microscope

Alan [w2aew] – tutorials on components; ham radio; RF

 

Security

Steve Gibson – Security Now podcast – a MUST for computer security folks; good episodes on internet components

 

Science & Math

Michael Stevens – Vsauce, The Mind Field

Grant Sanderson – 3Blue1Brown; math concepts, including a good visualization of Fourier analysis

Ben Sparks, Holly Krieger – Numberphile; math concepts, including large numbers and number theory

Matt Parker – Stand-Up Maths, lectures at Royal Institution

Brady Heywood – Understanding Complexity, complexity theory

Grady Hillhouse – Practical Engineering, particularly civil engineering

Collin Cunningham – “Lab Notes”, quick videos about electrical components and Adafruit products

 

Making, Robots, and Machinery

Adam Savage – amazing maker, MythBusters

Simone Giertz – general making, silly projects

Jeremy Fielding – general EE topics; built a cool robot arm

Tim Hunkin – very fun arcade game maker – machining tips

 

Other Sites of Topical Interest

The Cave Pearl Project – remote underwater sensing; excellent documentation of battery systems, sensors, builds

Interesting circuit uses only two wires for power and status (not TWI)

Comparison of manufacturers of PCBs in small quantities (incl. PCBWay, OSHPark, and JLCPCB)

How to use a thermal camera to troubleshoot electronics projects

Car security systems

Failures are important, and sharing them is more so

An interesting cascade of failures

NASA failure analysis

More NASA failure analysis

Mechanical analog fire-control computers

FloodNet – distributed flood sensing system for NYC

Arduino debugging

Acoustic detection of water leaks

Circuit board for a differential oscilloscope probe

Three designs for bidirectional voltage level shifting

Orange Pi 3b vs. Raspberry Pi

Battery monitoring

Introduction to Kalman Filters, useful for combining data from multiple sources

Ongoing project documentation

(Mis)using LoRa nodes to sense soil moisture

Mechanical neural network

Microphone array to isolate individual voices

Interesting uses of diodes

The Matter IoT Standard

Using the Matter protocol on ESP32

Building or buying contact piezo microphones

 

Internet Black Hole – Danger!

Destin Sandlin – SmarterEveryDay; how stuff works, including helicopters, nuclear subs, the James Webb space telescope

Derek Muller (PhD Physics) – Veritasium

Mark Rober – e.g. squirrel obstacle course, glitter bomb, world’s smallest Nerf gun

Markus Voelter – Omega Tau podcast; aviation, gliders, rides in fighters. Half of his podcasts are in English; the other half in German

 

Scary (but interesting) stuff – Don’t do this at home (nor at M5, nor for SDP)!!!

Mehdi Sadaghdar – ElectroBOOM; high-voltage stuff; fun to watch

Colin Furze – crazy powerful builds

Plasma Channel – plasma thrusters

Styro Pyro – big scary lasers

 

Apparatus to monitor the cycling of the hot tub pump

Posted on by CBMalloch

It’s working.

I may be having a problem with my hot tub pump – it’s running with shorter cycles than I remember it. That’s better for close temperature control, but worse for stress on the motor.
I had a problem with the pump’s computer unit once before – it was overheating and cycling more and more rapidly. So now I want to monitor it to see if its cycling is getting faster.

I can’t monitor it using a current sensor, since those ones I have are rated for 10A at 120V, while the motor unit uses 15A at 120V.

So I built a monitoring system – weather sealed a 1″ piezo disk, breadboarded a JFET amplifier for it, connected it to an ESP8266 microcontroller which I programmed to take readings at 480Hz, dot-product out the components at 60Hz and 120Hz (which for some reason is stronger) and send them via WiFi to my MQTT server, from which I scoop them with a Perl script to a log file (for now). I’ve determined the best discriminant between non-running and running with a z-score of 6.6+ from each, so I know it’s pretty good.
Now I can relax for a while while the data accumulates…

Data from the 60Hz and 120Hz dot-products:

7-Dec-2021 14:02:18: home/hot_tub_motor/a02/value/couplet -> 32.839 16.014
7-Dec-2021 14:02:24: home/hot_tub_motor/a02/value/couplet -> 29.103 16.061
7-Dec-2021 14:02:29: home/hot_tub_motor/a02/value/couplet -> 29.301 16.638
7-Dec-2021 14:02:35: home/hot_tub_motor/a02/value/couplet -> 32.062 17.769
7-Dec-2021 14:02:40: home/hot_tub_motor/a02/value/couplet -> 28.854 16.440
7-Dec-2021 14:02:45: home/hot_tub_motor/a02/value/couplet -> 33.069 16.328
7-Dec-2021 14:02:51: home/hot_tub_motor/a02/value/couplet -> 28.665 17.092
7-Dec-2021 14:02:56: home/hot_tub_motor/a02/value/couplet -> 28.019 18.892
7-Dec-2021 14:03:03: home/hot_tub_motor/a02/value/couplet -> 32.541 17.647
7-Dec-2021 14:03:07: home/hot_tub_motor/a02/value/couplet -> 29.323 16.411
7-Dec-2021 14:03:12: home/hot_tub_motor/a02/value/couplet -> 69.411 58.708
7-Dec-2021 14:03:17: home/hot_tub_motor/a02/value/couplet -> 38.942 56.288
7-Dec-2021 14:03:24: home/hot_tub_motor/a02/value/couplet -> 16.419 50.588
7-Dec-2021 14:03:32: home/hot_tub_motor/a02/value/couplet -> 25.903 59.193
7-Dec-2021 14:03:33: home/hot_tub_motor/a02/value/couplet -> 70.220 61.097
7-Dec-2021 14:03:40: home/hot_tub_motor/a02/value/couplet -> 60.011 61.728
7-Dec-2021 14:03:44: home/hot_tub_motor/a02/value/couplet -> 17.743 51.550
7-Dec-2021 14:03:49: home/hot_tub_motor/a02/value/couplet -> 37.571 57.612
7-Dec-2021 14:03:55: home/hot_tub_motor/a02/value/couplet -> 72.898 57.997
7-Dec-2021 14:04:00: home/hot_tub_motor/a02/value/couplet -> 23.630 55.861
7-Dec-2021 14:04:06: home/hot_tub_motor/a02/value/couplet -> 41.698 62.395
7-Dec-2021 14:04:11: home/hot_tub_motor/a02/value/couplet -> 56.960 59.568
7-Dec-2021 14:04:18: home/hot_tub_motor/a02/value/couplet -> 15.589 50.445
7-Dec-2021 14:04:22: home/hot_tub_motor/a02/value/couplet -> 71.046 62.314
7-Dec-2021 14:04:27: home/hot_tub_motor/a02/value/couplet -> 16.098 46.108
7-Dec-2021 14:04:32: home/hot_tub_motor/a02/value/couplet -> 70.857 61.175
7-Dec-2021 14:04:39: home/hot_tub_motor/a02/value/couplet -> 16.661 53.204
7-Dec-2021 14:04:45: home/hot_tub_motor/a02/value/couplet -> 73.267 63.262
7-Dec-2021 14:04:48: home/hot_tub_motor/a02/value/couplet -> 14.290 54.907
7-Dec-2021 14:04:54: home/hot_tub_motor/a02/value/couplet -> 70.185 61.067
7-Dec-2021 14:05:01: home/hot_tub_motor/a02/value/couplet -> 22.880 57.029
7-Dec-2021 14:05:06: home/hot_tub_motor/a02/value/couplet -> 51.657 55.721
7-Dec-2021 14:05:10: home/hot_tub_motor/a02/value/couplet -> 47.116 61.623

The hot tub motor started up at 14:03:12.

Data discriminated into “off” and “on”:

About to subscribe to topic 'home/hot_tub_motor/a02/status'
7-Dec-2021 14:42:21: home/hot_tub_motor/a02/status -> 0
7-Dec-2021 14:52:23: home/hot_tub_motor/a02/status -> 1
7-Dec-2021 15:03:02: home/hot_tub_motor/a02/status -> 0

I’m not sure why the vibration is at 120Hz and not at 60Hz. I’ll have to think about AC motors and how they operate now.

Yay! Another investigation!

Watchdog watchdog

Posted on by CBMalloch

Well. It’s been a while. Here’s what’s new:

I monitor my heating system (temperatures, zone activation) with an Arduino, and relay the values to my home monitoring system through an ESP-01 / ESP8266. The Arduino occasionally hangs up.

I have tried to fix this by checking the power supply for good clean power; by making it reboot itself every 24 hours; by enabling the ATmega328’s watchdog timer. It still hangs up.

When it is running, it flashes an LED connected to the standard pin 13 of the Arduino. I recalled seeing that a 555 timer could be used as a missing-pulse detector. This would trigger if the 1Hz flashing stops. Cool. The missing pulse detector takes its output low during pulse starvation, and takes it high during the happy times when the pulses continue. I needed to take that prolonged low value and turn it into a one-shot pulse to drop and resume the power to the Arduino, and a second 555 could be configured as a one-shot to create this pulse. I had to add a capacitor in between to prevent continuous retriggering of the second 555, which would keep the power off to the Arduino.

The circuit “1” in the schematic illustrates this setup.

I happened to have a 556 handy, which comprises the functionality of two 555 timers. The equivalent simpler circuit is “2” in the schematic.

But, duh. I’m really more of a programmer at heart. And I had some ATtiny85 chips around. So I created an Arduino program to embody all the above functionality in a much simpler circuit – “3” in the schematic.

Note: in the code and the schematic the name ATmega refers to the (processor on the) Arduino board.

Watchdog_watchdog_sch

And I put it all onto a very small solderless breadboard. Since I needed regulated 5V to feed all the components, I put standard voltage regulation onto the breadboard as well.

The Arduino program was very simple:


/*
  Watchdog_watchdog
  
  One of my Arduinos, the one that monitors temperatures and zone activations 
  in my heating system, occasionally hangs up. This despite the fact that I'm
  using the ATmega watchdog to automatically reset it if it hangs. Dunno why. 
  The power seems good and stable. I've tried replacing the ATmega chip.

  I've decided to kill a flea with a cannon. The ATmega blinks an LED at 1Hz
  to indicate that it's still alive - I call this a throbber. The ATtiny will 
  monitor the throbber and if it stops, it will power-cycle the ATmega.
  Hah.

  The MOSFET in question will be a p-channel MOSFET configured on the high side
  of the power to the ATmega; when its gate is pulled low, it allows power to 
  flow to the ATmega. The specific MOSFET I'm using is a 5LP01SP, which is a 
  p-channel device whose pins are 1=source, 2=drain, 3=gate.
  
*/

#define pdThrobber_in 3
#define pdMOSFET      4

const unsigned long resetAfter_ms = 2000UL;
unsigned long lastThrobAt_ms = 0UL;


void setup() {
  pinMode ( pdThrobber_in, INPUT );
  pinMode ( pdMOSFET, OUTPUT );
}

void loop() {
  static int throbberStatePrevious = 0;
  int throbberState = digitalRead ( pdThrobber_in );
  if ( throbberState != throbberStatePrevious ) {
    lastThrobAt_ms = millis();
    throbberStatePrevious = throbberState;
  }
  if ( ( millis() - lastThrobAt_ms ) > resetAfter_ms ) {
    // BOOM. Cause a reset
    digitalWrite ( pdMOSFET, 1 );  // turns off ATmega
    delay ( 500 );
    digitalWrite ( pdMOSFET, 0 );
    delay ( 5000 );  // time enough to let the ATmega boot up
    lastThrobAt_ms = millis();  // reset the watchdog
  }
}

EBD-USB+ Electronic Load – Testing Power Supplies and Batteries

Posted on by CBMalloch

I watched a video from Andreas Speiss reviewing electronic loads, and identifying one in particular called EBD-USB+ from zketech.com and purchased through Amazon or Banggood or wherever. The software is a little hard to find, but it’s available through this link. It comes as a .rar file, which you might need to unpack with 7-zip or Winzip. You will also need the driver.

[Read More...]

Teensy, touch sensing, and ESP8266 – via MQTT and Raspberry Pi

Posted on by CBMalloch

Whee!

I have a demo/development setup on a small breadboard which powers an ESP-01 ( the small, cheap, 8-pin breakout board for an ESP8266 chip ). In addition to being a programming board, it has 3v3 voltage regulation, a pot, a temperature sensor, a simple LED, and a WS2812 3-color LED. I have the installed ESP8266 running a program to subscribe to an MQTT broker and light the LEDs according to publications on a certain topic.

[Read More...]

Calculating the Axis of Nutation of my Solar Tracker

Posted on by CBMalloch

Following on the cluster analysis of the last post, I pairwise crossed (as in cross-multiply) the resulting cluster centers, and got three reasonably-close vectors after normalization. These were:

0 x 1: (-0.36, 0.93, -0.10)
0 x 2: (-0.23, 0.97, -0.06)
1 x 2: (-0.20, 0.97, -0.14)

While satisfyingly close, I wanted to do better.

[Read More...]

Instrumenting and Analyzing My Solar Tracker

Posted on by CBMalloch

I’m an instrumentation and data collection geek. I love the challenge of developing ways to monitor the systems of my house and making sure they’re working properly. I’ve had a couple bad experiences where systems failed and not knowing it soon enough caused problems.

[Read More...]