Sunday, December 1, 2019

Keurig Switch Mod

I recently bought a Keurig for $5 at Goodwill. I wanted to see how the design of it compares to my robotic tea maker.
It takes a while for the water to preheat. That uses 1.3 kilowatts for a total (48 watt hours) to get up to temperature, and then about 500 watts periodically to maintain. But even after pressing the off button, it still uses 6 watts due to the iron core transformer for the control circuitry.
To prevent the constant 6 watts, without having to unplug it all the time, I added an extra switch. This modification makes it possible to turn it all the way off without unplugging it each time.

Thursday, November 28, 2019

Teabot Upgrades

My teabot was only able to remove teabags after 3 and a half minutes, but sometimes I make tea that brews longer. So I decided to add a switch to allow for the removal of the teabag at an adjustable time. The switch determines which GPIO pin, if any, is connected to the motor. If pin 9 or pin 13 is connected to the servo, then it will remove the teabag at 3 and a half minutes or 5 minutes, respectively.
I also replaced the front panel, which was made of a very thin clear plastic, with a half inch thick acrylic panel that I got from my great uncle Mike.
There were also electrical issues. The lift motor was just barely working on the 5 volt output from the Arduino. The minimum voltage for the motor was 4.8. Sometimes it would cause electrical issues such as boot looping. So I added an LM7806 to the power board so I could run the motor off 6 volts, which is right in the middle of the voltage range.
When I reinstalled the power board, there was a short circuit between one of the inputs and the positive unregulated rail, this caused the transformer to dissipate over 100 watts and overheat, so I added a dual fuse holder, with 1 amp fuses. It would also reboot at the end of the cycle  (and start pouring the water over again), so I added an ac capacitor in parallel with the contactor

clear panel and new switch







Fuse holders

Sunday, September 29, 2019

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.


Saturday, August 17, 2019

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.


Sunday, August 11, 2019

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.


Saturday, August 3, 2019

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.

Friday, August 2, 2019

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.

Sunday, July 28, 2019

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.


Tuesday, July 16, 2019

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.

Friday, July 12, 2019

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.

Sunday, June 30, 2019

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);
}
}
}

Friday, June 28, 2019

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.

Thursday, June 20, 2019

Solar Power System Part 3- 2.2 Channel Speaker System

I have had an amplifier and speakers in my "lounge area" for a few years. I've changed speakers, amplifiers, and the power system a few times, but the basic set up is still the same. The  speakers I have now were part of a set of 5 that I bought at Goodwill. Now I finally have the speakers powered by my solar battery box.



The batteries are charged by the solar panel, and then connected to the amplifier, which is connected to 8 speakers. There are 4 speakers per channel, with 2 channels. I have 2 subwoofers and 2 full range drivers per channel. This creates a powerful, well-balanced sound in a small space. The amplifier is capable of putting more than 30 Watts into the speakers, but I rarely go above 1 Watt. Each of the full range drivers can handle 120 Watts. My original goal was to have a bed-shaking loud alarm clock powered by solar, but the alarm app wouldn't output at full volume and it wouldn't always turn on at the right time. 


I also added a laser indicator light so I remember to turn off the speakers when I leave the room or go to bed. If I leave it on, the speakers make random popping sounds that could damage them. The laser dot is projected onto one of the speakers. I got this idea from a hard drive light that projects onto the desk.

Impact Wrench Battery Rebuild


I bought an old Snap On impact wrench at a garage sale recently. It's a good brand that's usually too expensive for me to buy. It came with two batteries, but I thought even if I had to buy a new battery it might still be a good deal.
After testing it out for a couple of weeks, I found that one of the batteries wasn't holding a charge and the charger said it was bad. I attempted to charge it with a different charger, but it still wouldn't charge all the way. After looking at prices for the name brand battery pack, I decided to look at battery rebuild kits instead. The pre-assembled ones were still too expensive, so I decided to buy 12 individual sub C nickel cadmium cells and solder them together myself.
Opening the plastic case was straightforward, just requiring a T10 torx bit. I watched several Youtube videos on battery pack rebuilding so I knew what supplies I would need.

First, I arranged the cells in the same pattern as the original battery pack, and hot glued them together.
Then I used nickel plated steel strip to connect them. I was worried that soldering might make the cells too hot. The proper way to attach them would be with spot welds. Soldering did work, but the heat might shorten the lifespan of the cells. It was difficult to get the solder to stick in some spots, so I had to sand the ends of the cells

After I attached and connected the cells, I tested the fit in the original case and added a new piece of foam to the bottom. The cells seemed to fit well, but when I tried to slide the battery in and out of the tool, I found that the button on one side wouldn't release.  the negative connector was shifted slightly, so I had to take it apart again, and resolder one of the connections. After that, the buttons functioned perfectly. Now it holds a full charge.

Monday, June 17, 2019

Cordless Power Tool Storage


After watching a video on cordless power tool storage solutions, I decided to build my own. I wanted something quick and easy to modify later. Right now, I have 4 cordless power tool systems, each with a different charger and battery type. I have the Snap-On 14.4 V Ni-Cd slide battery, Craftsman 12V lithium, Worx 20V lithium, and Black and Decker 4V(internal lithium). I want to make sure the batteries are charged and ready for whatever projects my family is doing, and keep the spare batteries from getting lost.
To attach the Snap-On and Craftsman chargers, I used the keyhole mounts on the back. All I had to do was install 2 screws each, and then the chargers slide on because they are designed to be mounted. The Worx charger is not designed to be mounted, so I made a shelf for it. Then I added a piece of wood to mount the Snap-On impact wrench and its spare battery, and the Craftsman drill. I might need to add more wood to make a shelf with a back so things can't fall off.
I mounted a power strip above the chargers so I can plug them all in.
These are all around the end of the workbench on the left, easy to access from the door into the garage. The plan is to keep the area in front of the work bench and underneath mostly clear so that the truck could still fit in the garage if we get the rest of it cleaned out.

Power Strip

Wednesday, June 12, 2019

Beep Switch (Solar Power part 2)

One thing that the solar power system contains is a beeper. This is a continuation of the "dinner bell" project. Using one pair of wires from the phone lines in the house, my parents can press a button in the kitchen downstairs and it will sound the buzzer upstairs in my room. This is now successfully powered by my solar battery bank.

Wednesday, May 22, 2019

Solar Power System- Part 1- Battery Box

For my solar power system, I have an array of 3 12V 8 Amp Hour sealed lead acid batteries wired in parallel to get 24 Amp Hours. As a project for my shop class, I decided to build a nice box to store them in. I needed this because they are heavy and have to be moved with the rest of the charging circuit as a unit.  After I assembled the pieces of MDF and plywood, I painted them the closest color to white that was available. I added small hinges from a bucket sale at the local Habitat for Humanity Restore. The part of the project for class was just the woodworking, but I added a few switches at school. I also mounted an ammeter on the front, an automotive power outlet, and a desk grommet for the wires to pass through.



After I brought the box home, I added a ceramic handle on the lid. I installed the batteries, charge diode, 10 amp ATM  fuse, and a beeper for my dinner bell system. I added magnetic lid latches to keep the lid closed. The whole system is connected to a solar panel which charges the batteries. I mostly use it to power my speaker system.


Amazon Affiliate link to a 3 inch cord grommet: https://amzn.to/2JYSK6j
link for the fuse assortment I bought: https://amzn.to/2wdCWV1
link for 12V 8AH battery: https://amzn.to/2EpVrdk


Friday, March 22, 2019

Motorized Stirrer

I added a motorized stirrer to my overcomplicated tea maker. I used a motor from an electric knife and a small whisk. I attached the whisk to the shaft of the motor by twisting the wire like a threaded rod. It sometimes unscrews itself. I mounted it on a scrap of vinyl window nailing flange, so that it can be lifted up to insert into a cup and to absorb vibration. It's powered off the 12V center tap of the transformer, and switched independently. I tested it by making simple syrup, mixing 1 cup of natural sugar with 1 cup of hot water, and a teaspoon of vanilla extract. It worked perfectly.


Here's the Amazon Affiliate link for the sugar I used: https://amzn.to/2HzUl1R

TV Tuner Spider (from the archives)


This art project is made with an old TV tuner, coaxial cable, neon indicators, and spray paint. I kept the original power cord, but took out the circuit board. I got it out recently to try to play a joke on my uncle who was visiting. I put the giant spider with glowing eyes and mouth near his suitcase, but he didn't even pretend to be scared.

Sunday, March 17, 2019

Overcomplicated Tea Maker

One time when I was doing homework, I asked my dad to make me a cup of tea. He used the convenient small coffee maker, but left it on too long. That wasted power and could have started a fire. After that, I decided to add some features to try to make a perfect cup of tea and maybe save power.

First, I added an arduino-controlled 3 phase 40 amp contactor to turn the coffeemaker off automatically. There are coffee and tea makers that already have a timer, but the one I have doesn't stop at exactly three and a half minutes. A contactor is like a really big relay, typically used for industrial control and air conditioners. I bought a contactor at the Habitat for Humanity ReStore, and I was looking for a project to show it off. The arduino controls the contactor via a relay.

I added a 20 amp light switch to start it. I attached a metal electrical box to hold teabags. I thought about adding a motorized arm to lift the teabag, but I didn't know how to program that. I might add a stirrer for sweetened drinks. 

Yesterday, I added a platform so that it doesn't take up as much space on the counter. I used a mesquite log, and wood recycled from our old windowsills. I tried to use velcro to keep the coffee maker from falling off the platform, but it stuck to itself better than it stuck to the plastic. Next, I tried duct tape, but it didn't look right. I unscrewed the bottom to clean the inside (because a few years ago some ants invaded it). When I took off the bottom plate I found better solution. I screwed the bottom plate directly to the platform, and then reattached it to the coffee maker.






Amazon Affiliate link for the contactor: https://amzn.to/2OcsZQ2
Amazon Affiliate link for Mom's favorite tea, (lemon ginger): https://amzn.to/2TGzhgF

Friday, March 8, 2019

The Power of Ice

Our weather has been going from hot to cold and back. A couple of days ago, I wanted to do an experiment of leaving a soda can full of water outside overnight because it was going to get down to 24 degrees Fahrenheit (-4 C). Unfortunately, my mom didn't know what it was for, and used it to water her plants. And the next couple of nights, the low temperature was around 65F. So I had to try the experiment again in the freezer instead.
Ice can be very powerful. Glaciers. Frost heave. Burst pipes.
Even though the top of the can had an opening for water to escape, the ice blocked it. It split the can!

Monitor Stand Adapter

My computer has an ultrawide monitor. It's great, but it takes up a lot of desk space. I decided to replace the stand with an older one(I think it's from 2003) that has adjustable height and rotation. Then I can put my speakers underneath and use more of my desk space. I made an adapter plate to attach it by drilling extra holes in the VESA mount because the mounting holes are closer together than the ones on the stand. I tested it in "portrait mode" with Minecraft, and it looks crazy. It is not practical for gaming, but might be good for reading text. After that, I rotated it back to normal, but adjusted the height so it's about 6 inches off the desk. The stand that it came with only does tilt.


Here's an Amazon affiliate link for the monitor I have: https://amzn.to/2TpebmN

Sunday, March 3, 2019

Drill Bit Sharpener

I have wanted to try re-sharpening drill bits for a long time. I think it would be a good way to reuse something instead of throwing it away too soon. I had seen one called the Drill Doctor on Youtube that has its own motor, but it was too expensive. I found a drill bit sharpener at Harbor Freight that was a reasonable price and decide to try it out.

You can buy it online through Amazon, but it costs more. Here's my affiliate link: https://amzn.to/2ExXew8

The sharpener is a grindstone with a jig attached. It works on 2 mm to 12.5mm bits. To use this, you need a drill that spins between 2000 and 3500 RPM. There's a typo on one side of the package that says it could work at 35000 RPM, but I don't think that would be safe. I used my drill press at 2100 RPM and it worked on my first try. It got the bit sharper, but the point and edges aren't perfect. I think I could get better at using it with more practice.

I saw a video on Youtube about a giant automated drill bit sharpener. It was really cool, but it is meant for much larger drill bits in an industrial environment. Here's the link: https://www.youtube.com/watch?v=jx_9GK3sF6g&t=4s