Large Alarm Bell

I bought this large alarm bell for 5 dollars at a Habitat for Humanity Restore. I modified it by bypassing the mechanical oscillator, to make it ring only once per press of the button. I used a MOSFET to drive the bell because the bell was too powerful to be controlled directly. I used it to replace the buzzer in my solar power/ dinner bell system. I needed it to ring only once so my dad couldn't be annoying and hold the button down too long. Also, it could have been so loud that the neighbors might think it was a fire alarm. Its original purpose was to be a security alarm. I thought it would be cool to have a 7 inch diameter alarm bell.

Power Meter Kit

I wanted to see how much power different devices used and what the power factor was. Power factor is how synchronized the current and voltage are. A power factor of 1 is perfect, close to 0 is really bad. A device that pulls 1 Amp and 60 Watts at 120V will have a power factor of .5, because the real power (Watts) is half the apparent power (VoltAmps).
I have some smart plugs that claim to measure Watts- but actually measure VoltAmps. Sometimes their measurements were 25 times higher than it really was because the power factor was .03. They would say a device used 50 Watts, but was actually only using 2 Watts (and 50 VoltAmps). Other meters such as the KillAWatt 4400 measured things more accurately but only displayed one thing at a time.
I decided to buy a panel mount power meter instead of a self contained one, and add my own case and cord. The one I ordered came quickly through Amazon, and I hoped it would be a quick project. Unfortunately, cutting the opening in the metal case was more difficult than I expected. I used a cordless jigsaw, which is not the most accurate. Eventually, I did get the meter to fit, and then added a 14 gauge cord. For now, I added a colored tape wrap on the case. Maybe I will find some spray paint for metal and redo it.
After I set up the meter, I tried it out on some home electronics.
Laptop- 30 Watts with a power factor of .5
TV- 120 Watts with a power factor greater than .9
Bench supply- 8 Watts with a power factor of .6
1.5 Amp phone charger- 8 Watts with a power factor of .6

This meter can measure up to 100 Amps but the plugs in our house can only supply 15. It can measure up to 260 Volts, but 120 Volts is the highest I can plug it into because of the limits of the US power system.

2-channel computer speaker system (solar power part 4)

I found speakers that attached to the side of an old TV. They could be used with individual stands or bolted to the side of the TV. The amplifier inside the TV failed, but the speakers were fine. They sounded better than my previous computer speakers, and could be powered from my solar power system. So I decided to swap them out, and build a wooden stand to hold them. I used scrap wood from IKEA furniture that matched my desk surface, and old fence boards for the uprights.

 I also mounted a switch and an amplifier on the speaker stand.

The new speakers with stand are better because they take up less desk space, sound better, and use solar power.

Recycled Soap #5

After our annual summer vacation family road trip, I ended up with a whole bunch of tiny hotel bars of soap. I decided to combine them with a few from previous years that I had tinted, to make a larger ball of soap that would be easier to use. I used the same process as the previous batches. I shaved them into curls, chips and powder depending on the properties of each bar of soap. Some were ductile and some were brittle. I used a knife that I sharpened with a sharpening stone I bought on the trip.
I added water to make the bits stick together, shaped it into a ball, and set it aside to dry. I am interested to find out how much weight is lost as the water evaporates. The ball of soap is 7 degrees F below room temperature, which suggests that water is currently evaporating.

Power Supply- Beryllium Oxide Thermal Conductor

I recently visited my Great Uncle Mike, who has an amazing inventory of electronic parts in his workshop. I talked to him about some of my problems with past projects and how I'm still learning about electronics. One of the projects that could be improved is my bench power supply. When I first added the 3.3 volt rail, I used thermally conductive double stick tape to attach the regulator to the heat sink because I didn't know any better. It needs to be electrically isolated because the tab is connected to the output of the regulator instead of connected to ground. He suggested a much better solution- a beryllium oxide ceramic material. BeO is about as thermally conductive as copper, but not electrically conductive. He said that this type of material is not used much in consumer electronics because it is expensive and the dust from it is highly toxic. It might be more commonly used by the military or NASA.

pop socket repair

The cap to my pop socket phone holder broke. It was held on by 4 tabs that fit into small slots in the plastic.
I made a replacement cap out of three different pieces of wood. I glued it with wood glue and clamped it. Then I cut it with an adjustable hole saw. But forgot to account for shrinkage when sanding, so it's a bit small. sanded, clear coated, attached with tiny nails with heads large enough to stay in the slots. I also glued in a piece of dowel to fill the hole.

Tea Machine- Splash Shield

To protect the arduino and other electronics from being splashed, I added a cover made of clear plastic, this also helps support the switch box. It might look better with a slightly frosted plastic to hide the wiring, but for now I just used the clear plastic I already had from a large pretzel container.

Tea Machine- Indicator Light

The next addition to the tea machine is an indicator light that sits just under the coffee maker base. It has three 5mm LEDs, one for each time setting. The green is lit up from 3 and a half to 5 minutes, the yellow indicates 5-10 minutes, and the red is 10 plus minutes. The yellow has a white lens. I added 1000 ohm resistor, shared by all three LEDs.
The timing of the lights is controlled by the arduino. I added the code for the timing of each light. The pins needed to be configured as OUTPUT in order to send the correct current to the LEDs.

Tea Machine- Now with Robot Arm

My tea maker project is built around a basic coffee maker. I added 3 timers powered by an arduino uno. After the first 3.5 minutes, the contactor turns off the power to the coffee maker to stop dispensing hot water. After 5 minutes, a buzzer goes off. After 10 minutes, another beeper sounds.

This week, I replaced the AC adapter I was using with a power board. It has a common cathode dual diode, a capacitor and an LM7809.

The newest part I added is a servo motor attached to a bent plastic knife to take the tea bag out automatically after the first 3.5 minutes. I had started working on this 2 years ago, but now I have finally added the code needed to control the servo. The first test didn't go so well, jerking the tea bag out too quickly and splashing hot tea on the counter. To fix it, I could have changed the code to run the motor slower. Instead, I hung the tea bag closer to the end of the arm, and added a splash shield.

here is the code:
#include

Servo myservo;  // create servo object to control a servo
int pos = 0;    // variable to store the servo position
int loudPin = 12;               
int HotPin = 11;
int louderPin = 10;
void setup()
{
  myservo.attach(9);  // attaches the servo on pin 9 to the servo object
  pinMode(loudPin, OUTPUT);
  pinMode(louderPin, OUTPUT);
   pinMode(HotPin, OUTPUT);// sets the digital pin as output
}

void loop()
{ for (pos = 90; pos <= 177; pos += 1) { // goes from 0 degrees to 180 degrees
    // in steps of 1 degree
    myservo.write(pos);              // tell servo to go to position in variable 'pos'
    delay(15);     
  digitalWrite(HotPin, HIGH); 
  delay(210069);                 
  digitalWrite(HotPin, LOW);
  for (pos = 177; pos >= 90; pos -= 1) { // goes from 180 degrees to 0 degrees
    myservo.write(pos);              // tell servo to go to position in variable 'pos'
    delay(15);   
  delay(90000);
  digitalWrite(loudPin, HIGH); 
  delay(3000);
  digitalWrite(loudPin, LOW);
 delay(300000);
  digitalWrite(louderPin, HIGH); 
  delay(3000);
  digitalWrite(louderPin, LOW);
  delay(3000000000000000420);
}
}
}

Quick Connect Pressure Gauge

After replacing a failed regulator, I decided to reuse the old gauge from it in a project. I used a 1/8NPT27 tap to cut threads in the inside of a male Quick Connect fitting. Then I screwed the two parts together and wrapped electrical tape around it to provide a softer grip. (The tape is not for pressure or sealing leaks).

I can use the gauge to check the pressure coming from an air hose, without having to go look at the stock gauges on the air compressor. Our compressor stops at 120 psi, but the gauge can measure up to 160 psi.