Friday, March 16, 2018

Overcomplicated Alarm Clock

Bored by the standard clock radio, I wanted something with bed-shaking bass to wake up to. I decided to modify my sound system to add a secondary power input controlled by a mechanical timer. The timer is the type you plug your lamp into when you go on vacation so people think you are home, although that didn't work in the Home Alone movie. I set the timer to turn the power on for about an hour around the time the alarm app on my tablet is set to. The app on my tablet is set to use loud music as the alarm. My favorite is a song called Gopnik by DJ Blyatman. I don't understand the words, but I like the style.
To prevent the two power supplies from interfering with each other, I added a common anode dual diode (STPS3045CW). Here is a datasheet from the manufacturer. I salvaged the diode from a switch mode power supply.
The green LED indicates power from the bench power supply. If it is on it will be the dominant power source. The orange light indicates the alarm power source. If both power supplies are on, the bench power supply will do the work.
The blue part is the amplifier. I use it all the time when I am listening to music. My tablet by itself has tiny speakers and therefore no bass whatsoever. I bought the amplifier through amazon.

Monday, March 12, 2018

Instructions for Light Sensor Learning Kit

I signed up for the Amazon Affiliate program. This gives me a small percentage if someone buys a product through my affiliate link. It doesn't cost the buyer any extra, and I can post a link to any product they sell (except gift cards). This inspired me to put together some easy electronics projects with a list of links so you can build them yourself. 

Last year at the Austin and Floresville Maker Faires, I showed off my "Electronic Pinscreen" project. Here are instructions for how to build your own on a much smaller scale.

To build a smaller version of my LED matrix, you will need 4 LEDs, 4 light sensors, and a battery pack with batteries. While you can buy smaller packages of parts, it's a much better deal to buy them in bulk. For 12 kits, the total price would be around $30.
Now that I'm old enough, I solder all my projects. Maker Faires are a good place to learn how. I went to a class at the Austin Maker Faire a long time ago, and the Kansas City Maker Faire in 2017. But if you don't know how to solder, you can do this project with breadboards instead. Or have the kids twist the wires together and test it, and then have the parents solder it. Lead-free solder would make it safer for kids to handle the finished product. I don't like lead-free solder because it's harder to work with. (Safety note from Mom- soldering should be done in a well-ventilated area on a non-flammable surface that isn't your fancy dining table, with experienced adult supervision because it's over 600 degrees F, and make sure to wash hands afterwards.)
Take two 4" pieces of bare wire, lay them out parallel, about 2 inches apart. Connect all the negative (short legs) of the LEDs to one bare wire. Connect one side of each photocell to the other bare wire. Connect the positive (long leg) of each LED to the other side of each photocell. Connect the red (positive) wire from the battery holder to the bare wire with photocells. Connect the black (negative) wire from the battery holder to the bare wire with the LEDs. It should match the schematic.
Test, and then solder.
You can mount the finished project on cardboard to keep it secure.

Parts list for 12 kits:
uncoated or stripped wire, 8 inches per kit
50 white LEDs
(20+30) Photoresistors and
12 Battery Holders (hold 2 AAs each)

Optional- 2 six-packs of mini breadboards
24 AA Batteries-

Sunday, December 31, 2017

Salvaging Electronic Components

I took apart an old electric pressure cooker because the coating inside the pot had started to flake off and the metal underneath was oxidized. It wasn't safe to to cook with anymore, so I decided to take it apart and see what components I could salvage. I have always liked taking things apart to see how they work, but it's only been within the past year that I've had the right tool to take it this far apart to save individual components without damaging them.
Even with the desoldering tool, sometimes the pcb gets damaged but the components are usually fine. The capacitors may have a shortened life span due to the heat. The desoldering tool has a soldering tip with a hole in it and a vacuum pump. It melts the solder and then sucks it into a chamber where it is stored until enough builds up that it comes out when resetting the plunger. I have a can to collect the used solder in so that it doesn't get on the workbench or in the fume extractor. 

In the pressure cooker, I found a 555 timer and an LM7805 voltage regulator. The 555 timer came out relatively easily, but the LM7805 didn't. I salvaged a passive piezo.

I was also able to desolder 2 LEDs and a capacitor. It was mostly solid state controls, there weren't any relays. There was a chip labelled BTA16 600B on a large heat sink, but it didn't need to be desoldered.  I looked up a datasheet for it, and it is a triac (a type of solid state switch for AC).

Wednesday, December 27, 2017

Recycled Soap #2

For this batch of recycled soap, I used a base bar from the previous recycled soap with other chopped up soap scraps. I soaked it in water with green food coloring, and then squeezed it back together. This reminds me of a type of rock similar to granite.

Tuesday, December 26, 2017

LED and rectifier tester

This project is a tester for bridge rectifiers and LEDs. It contains a transformer that outputs 22 volts open circuit when powered by my isolation transformer. It contains an internal bridge rectifier which powers the LED tester. The bridge rectifier tester works by sending either half of the sine wave transformer output to the bridge rectifier to test each pair of diodes. If the bridge rectifier is good, the LED will light on both polarity switch settings.
The connectors are 4 pin .1 inch for the bridge rectifier tester and 6 pin .1 inch for the LED tester. 3 pins are positive and 3 pins are negative. I stick an LED into the connector with 1 pin into each side. If the LED is good and the polarity is correct, it will light.

Sunday, December 3, 2017

Barbecue Thermometer Holder

My dad kept losing his meat thermometer and asked me to make a holder for it. So I made one out of a 7/8 to 3/4 copper reducer. I used my drill press to make a 5/32 hole in the ⅞ part. Then I used a screw to cut threads. Then I used the same screw to mount it to the cabinet of barbecue stuff by the back door. It only took 5 minutes to make, but most of that time was finding the chuck key for my drill press.

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.