Saturday, May 19, 2018

Bluetooth Audio Receiver Bracket

I got a new bluetooth audio receiver, and I needed to find a way to keep it organized and off the floor. My desk is too far away for the output cable, and I didn't want to put it under the mattress. So I decided to make a mounting bracket for it. I decided to use scraps of balsa wood from my engineering class. Even though balsa is extremely soft, it is considered a hardwood based on the type of seed. It is so easy to cut that we used utility knives to cut it in class. At home, I decided to use my bandsaw because it safer and more accurate. And I don't have a laser cutter.
The bracket is a ring that is the right size for the bottom part of the receiver to fit through, but small enough that it doesn't fall all the way through. I held the layers of the ring together using standard wood glue. Then I used cyanoacrylate to attach a mounting plate. Then I screwed the mounting plate to the same bracket that holds my speakers under the bed.

Saturday, March 31, 2018

DIY Sisal Bristle Oil Brush

I recently have been doing a lot of drilling through metal which requires cutting oil to keep the bit sharp . I’m using used air compressor oil (stored in a plastic water bottle) and I needed a brush to apply it. The silverfish ate the bristles of all the old brushes I had stored in the shed, so I decided to make my own. I made a brush out of sisal twine, aluminum tubing, and an old screwdriver. It's hacked together but it works quite well. The section of sisal twine is held in place inside the tube by a screw. When the bristles wear out, it is easy to replace with a new piece of twine.

Sunday, March 18, 2018

Buzzer with Antique Capacitor

This circuit uses a momentary push button, a buzzer, and a capacitor. I got this antique capacitor from an estate sale. It is over twice the size of a modern one of the same capacity and voltage. (400 μF at 25 Volts). A similar size modern capacitor has about 12 times the capacity at the same voltage.
This is one of my projects that has been shown at the Austin and Floresville Maker Faires. I plan to show it at the San Antonio Maker Faire soon. This is a favorite among kids, who like to push the button repetitively.  The capacitor stores power and slowly releases it. This gives the buzzer an interesting sound. Dad describes as annoying and Mom says it sounds like a cartoon spring "boing".

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.  https://www.youtube.com/watch?v=2tch4J_pP9o 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. http://amzn.to/2HCxCOw

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 http://amzn.to/2Dnzp7G
(20+30) Photoresistors http://amzn.to/2GlVtD1 and http://amzn.to/2GkeqG1
12 Battery Holders (hold 2 AAs each)  http://amzn.to/2p4AUDr

Optional- 2 six-packs of mini breadboards http://amzn.to/2FM5k7e
24 AA Batteries- http://amzn.to/2Hrdn6q

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).  https://www.rcscomponents.kiev.ua/datasheets/haopinfsj489ydf945dt.pdf


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.