Sunday, August 6, 2017

Recycled Soap #1

We recently went on a long vacation and collected some partially used bars of hotel soap. Griffin did not want to waste them, so he saved the scraps and decided to recycle them. One of the complete bars of soap had a dish shape. Griffin decided to fill it in with soap scraps. He cut other bars of soap into small pieces. He added liquid soap colored with green food coloring as a glue. (Be careful, too much food coloring can stain your hands, clothes, and surfaces) Then he mashed them together to make a flat surface. Hopefully, then liquid soap will dry and hold it all together. He hasn't tried washing his hands with it yet, but it looks like a nice art project.
Update: after washing with the soap, Griffin says that it worked very well. The soap suds filled in some of the crevices, blurring the pattern slightly but making it stick together even better.

Saturday, May 20, 2017

Room Doorbell with CAT5e Connection

Griffin has had several different version of a doorbell for his room over the years. The previous version used  22 AWG 4-strand wire, running down the hall, over the railing, and down the stairs. It was perfect for Mom & Dad to call him to dinner or wake him up for breakfast without having to yell up the stairs. It's not as elaborate as an intercom system, and not as modern or expensive as families sending texts to each other, but Griffin built it all by himself and it works perfectly. 

The newest modification that he added to the doorbell system was to send the signals through the CAT5e wires that were not being used in the house. Mom and Dad added them at the time the house was being built, but that was before WiFi became standard. Griffin's disclaimer- make sure you don't plug in actual network devices while using it for the doorbell system because it could damage the devices since it doesn't use standard Ethernet protocols.
On the downstairs end, Griffin added a pushbutton with a wall plate that matches the others in the house. This hides the wires and make it blend in with the other plugs and switch plates in the house. Behind the plate, he has tucked in extra wires and a beeper so that it works both ways. The beeper is still plenty loud downstairs even though it is covered up by the switch plate. When Mom or Dad press the button to ring his doorbell, he can respond by pressing the button on his end to acknowledge that he heard it.

Upstairs, the system gets power from a plug on the wall, and has a connector for the other end of the CAT5e wire. There wasn't enough space at the wall plate for the wires and beeper and it was hard to reach, so he added a longer wire that passes through yellow plastic tubing, and mounted a round button on the end to make it easier to reach. Griffin and Mom get a "kick" out of pressing the buttons with their feet.

Saturday, May 13, 2017

Fractals with Names

One of the projects at Griffin's table at the Austin Maker Faire is fractals with names. This project was mostly Mom's idea, but Griffin helped. We made ten sample fractals that visitors could pick from.

Here are some examples:

Monday, April 10, 2017

Homemade Power Supply Update

I decided to add a power switch to my homemade power supply when I  found a really interesting light switch at the Habitat for Humanity store in Round Rock. The switch has two buttons, on and off, unlike the single lever of most light switches.

 I also upgraded the FULL BRIDGE RECTIFIER from 800V 8A TO 50V 25A, added more voltage rails, and more smoothing capacitors on the unregulated rail.


Capacitors







Wednesday, January 18, 2017

Shaky Stick with Pig Tail (Unbalanced Motor with MOSFET)

 
This project is basically a stick that shakes with a fake pig tail. I recently took apart my old talking stuffed animal toy called Piggy Says. It was an interactive game based on Simon Says. I wanted to reuse parts of it, such as the switch in its tail and the vibration motor that made it seem like it was laughing. The 3 AA battery compartment was from another toy I took apart, because the one from Piggy Says was corroded. The switch was designed to signal an integrated circuit which means it can't handle much current. That's why I added a MOSFET which can handle a higher current. I put a capacitor across the motor to protect the MOSFET from inductive spikes. I added a pull down resistor on the MOSFET to prevent it from turning half on which would cause it to get hot. 



The motor with unbalanced weight.

Resistor

MOSFET with heat sink (which wasn't really necessary)

Friday, December 23, 2016

Christmas Ornaments 2016

Griffin made these wooden Christmas ornaments from scrap wood he got from Lowes and Home Depot. He used a pattern for a simple tree, and then cut it out with his scroll saw. He drilled a small hole with the drill press so he could hang them. He added patterns with woodburning. Then he put a small nail through the hole and dipped them in clear coat and then let them dry, except for the green one which Mom brushed with clear coat tinted green with oil paint.





Thursday, December 22, 2016

Power Tool Battery Charging Station


I built this power tool battery charging station so I could keep my Craftsman 12 volt drill battery and Worx 20 volt weedeater and switchdriver batteries charged. Mom likes this because it keeps these chargers out of the kitchen. The charging station consists of a short extension cord mounted to the underside of the workbench, a power strip, and a shelf for the Worx 20 volt battery. I used 2 pieces of scrap wood from pallet dividers, screwed to the underside of the main supports of the workbench. The shelf keep the battery off the workbench. The craftsman charger doesn't need a shelf because the charger is mounted to a post.
The Worx battery is 27 watt hours and charges at 14 watts. The Craftsman battery is a much smaller capacity but charges at 45 watts. Since the Worx battery is larger, I think it would work better if it charged with a higher power. It takes four times longer to charge. The only good thing about charging at the lower power is that it might make the battery last longer. Judging by the shape of the Craftsman battery, it appears to contain 3 lithium cells in series. The Worx battery appears to contain ten cells, with five sets in series of two parallel cells.
I like lithium ion cordless drills for driving screws because they are lightweight and have a higher pwm frequency compared to corded ones. NiCad drills have heavy batteries but they seem extremely wimpy.

Monday, December 19, 2016

Homemade Bench Power Supply

This is a benchtop power supply I made from a landscape lighting transformer. It has a bridge rectifier, a large heat sink, and 2 linear voltage regulators. One is for the 9-volt output and one is for the 5-volt output. It has 2 incandescent light bulbs wired in series to reduce current draw. It has a max total DC output of 3.5 Amps. It has max output of 1 amp per regulated rail. All the power consumed by the voltage regulators goes through the heat sink so that I only have to run 2 wires to each. 

This is useful for testing circuits, such as 5-5-5 timer circuits. The 5-volt rail is good for testing circuits that normally use a 9-volt battery so that the components aren't damaged by excessive current. I can charge 9-volt batteries through the 9-volt rail. I use another incandescent light bulb when charging the 9 volt battery to limit the current and indicate when the battery is full. 








9 volt regulator

5 volt regulator
bridge rectifier

Doorknob-based Switch

This circuit that turns a motor on and off is based on an old doorknob from our house. If the doorknob is not turned, the motor doesn't run. Turning the doorknob in one direction or the other completes the circuit and determines which direction the motor spins. This type of switch is a momentary single-pole double throw switch with center off.

Sunday, October 23, 2016

Homemade single battery flashlight

I built this flashlight based on a solar garden light for the boost circuitry and LED. The switch is an American light switch. It uses a single AA battery. The battery door is a 2 1/2 inch hinge. The battery spring is loose in the battery compartment, not attached to the hinge. The positive end of the battery is pressed up against a piece of 14 gauge wire that connects to the switch. I started with a block of wood that's 10 3/4 inches x 2 3/4 x 1 1/2. It's heavy and not very bright, but I plan to use it as a night light. In order to replace the battery, you have to first remove the screw, then open the battery door without losing the spring. Then use the screwdriver to push the old battery out from the other end and then push in a new battery, positive end first. Then put the spring back in, close the battery door, and screw it back on.