Capacitor Replacement

The arcade I work at has laser tag. The players wear vests with sensors. The laser tag vests plug in and hang up on chargers whenever they're not in use. However, the power supply wires are a little bit too big for the terminals, which causes the wires to come undone sometimes. While I was away, my boss tried to repair one of them but he reversed the copper and silver leads. This caused a tantalum capacitor to fail violently. 

I took off the plastic cover to see the board, and found a burned capacitor. I took it home and found a replacement aluminum electrolytic capacitor with the same value and sufficient voltage. 

My drawer of capacitors

I have my drawer of capacitors organized in a way that works for me, but might look messy on first glance. The handwritten number on each label is the voltage. The top number is the measured value of the capacitor, and the 2nd one is what it should be (nominal), and the 3rd number is the ratio. 

I desoldered the old capacitor and put the new one on. It was larger than the old one, but there was plenty of space under the cover. I forgot to clean off the flux residue, or cross off the sticker that said "lead-free".

I took the charger back and it worked perfectly.

From the Archives- Umbrella Recycled into Haircut Cape

Many years ago, I had an old umbrella with cartoon characters on it but it was broken. I pulled the fabric off the frame and saved it to recycle. It ended up with a hole in the middle, so I couldn't turn it into an umbrella hat, but I still tried sticking my head through it. 

That gave me the idea to turn it into a haircut cape. I had my mom sew knit fabric around the hole. Adding some elastic or velcro could make it fit better, but I never bothered.

When I was little and used to get haircuts at home, this cape helped keep the cut hairs from getting on my shirt. And because it was made from an umbrella- it was completely washable.

VR Accessory Repair- Woojer

 

The Woojer Strap Edge is a wearable accessory that's similar to a speaker. It gives VR games an extra-realistic experience by adding haptics. So if there are special effect noises in the game, you feel them as vibrations. 

I really like using the Woojer, so I was very disappointed when the switch on mine recently broke. The light would come on when I plugged it in, but nothing happened when I pressed the button. No clicking, no "switch feel". So I guessed correctly that the switch had gotten pushed away from the plastic button.

I wrote to the company to see if it might be covered under warranty, but I was too impatient to wait for a solution from them. Plus I really wanted to see how it worked. I decided to open it up and fix it myself. This was a difficult decision. My parents advised me not to do it, because there was a risk of either not being able to repair it, or a chance that it could break worse in the future. But I felt confident that it I knew what the problem was. Luckily, the electrical connections were all intact.

Looking inside the Woojer, I could tell that either the PCB pads lifted off or the solder on the support tabs of the switch broke. I tilted the switch back in place and then added hot glue between the switch and the oscillator can. That way the switch has support behind it keeping it in place even if the plastic button is pressed too hard or at an angle.

I found out that the rechargeable battery inside is a 12 watt hour 18650, so it would be relatively easy to replace if it wears out.

I put back the 5 screws that hold in the PCB, and the 4 screws that hold the case together. Now my Woojer is working again so I can use it when I play VR games like Beat Saber.

Update: After I got a response to my email to Woojer, I let them know I had already fixed it myself, and gave them a suggestion of how they could make their product better. Here's their reply:

Hi Griffin,

​

Quite impressive! I am glad you were able to resolve the problem and I will be sure to pass this on to our engineers.

Please let me know if there is anything else I can do for you.

Sincerely,

[Customer Support Representative]

Dragonfruit Lemonade

I like the fruit-flavored Refreshers at Starbucks. But they are expensive, contain caffeine, and the store has limited hours. So I decided to try to making my own. My version doesn't have green coffee juice, so no caffeine. I wanted to buy chunks of freeze-dried dragon fruit, but it was cheaper to buy powdered. This does make it easier to mix. I also got True Lemon crystallized lemon because I can't store any fresh fruits. I mix these with sugar, add some water, and then I stir it with my IKEA Produkt electric milk frother. Next I add ice and more water, and stir it again. Then if I serve it in a rinsed Starbucks cold cup, it looks almost like the real thing.

Here are some Amazon affiliate links to the products I used:

True Lemon https://amzn.to/3CYecRp

Dragon Fruit (Pitaya) https://amzn.to/2Yrw48k

Sugar (may be cheaper to buy locally) https://amzn.to/3mUhGP6

 

Battery Testing Jig

 I like to test the batteries I have collected to see whether they still have any life left in them before sending them to be recycled. This can be a tedious process, so I wanted to make part of the process easier.

This battery testing jig uses a foot pedal (doorbell button) to activate a solenoid (powered by 4 AA batteries). This pulls the battery into place between the solenoid and a screw at the other end. This connects the battery to my multimeter, without having to hold a lead in each hand while simultaneously trying to look at the multimeter. I can then sort the batteries according to the results.

Testing Jig

Foot Pedal

The Two-Timer

This project started out as just a battery replacement, but then I was inspired by a dad joke to make a dual timer. The goal was to convert the timer to use AA batteries, because they are easier to find than button cell types. 

I added a new battery compartment that's shared by both timers and a new speaker for one of them. One of the timers had more problems. It had a loose connection, which I had been able to fix with a shim at first. But after adding it to the project, it turned into a broken solder connection on the board. After I fixed it, it was still a bit loose so it still needed a shim. Now it's OK when the cover is screwed on.

After attaching the new battery compartment, I glued the parts to a board and added magnets so it can stick to the refrigerator.

Paper Art Collage- from the archives

 Griffin has always liked making collages. Fabric, paper, wood, or plastic. This series is from about twelve years ago. He stapled sequins, paper, pencil shavings, leaves, and other decorations to squares of paper. This is a good technique for kids to create quilt like designs, without using a sewing machine or globs of glue (if you don't mind look of the staples in the design).

Battery Storage Tube

 I wanted to create a sturdy storage tube for batteries that I can throw into my backpack. I used some old garden hose parts and pvc pipe to create a container with a screw on lid. When I was done, I decided it needed some decoration and reinforcement, so I wrapped it in colorful duck tape. I had intended it to hold 2 batteries, but I cut the tube longer so it actually holds 3 AA batteries. 

Don't Trust Wirenut Color Coding

 

The three wire nuts above are the same color, however they are not the same size. Below you will see more wire nuts but their sizes and colors are different. This could be because they were made by different companies, or they could be defective. There's usually an industry standard for which sizes are which colors. These annoy me because it makes it more difficult to sort them. Do I sort by color or by size?

Melted Plastic Art- from the Archives

 

Several years ago at the Austin Maker Faire, I had a booth demonstrating plastic melting art and other projects such as a kazoo made out of a plastic straw. I had a lot of time while I was sitting there to come up with new projects. Another booth had empty plastic tape dispensers and I combined them with scraps from the plastic straws to make more melted plastic art. This is similar to fused glass art, but doesn't require special equipment and works at a much lower temperature.

This is another plastic melting experiment. I baked the lid of an egg carton. The whole thing shrank down to about 2 inches long, including the words and the barcode which seemed to be a sticker made out of a different type of plastic.

Here's a few more. The green one my mom made. It was a type of plastic that didn't shrink, so the effect was just the cut edges curling up. The white blob was an entire styrofoam cup with lid. The orange creation was made with thicker plastics, including a laundry soap bottle.

Lately I have been using a heat gun for plastic melting because my plastic melting toaster oven is in storage. I had been getting paper cups with plastic lids every day from the dining hall, so l've been trying to make the stack of lids into a coaster.