Category Archives: Electronics

Cuttlefish Comm Board – Update 1

Posted on by

In my original post Cuttlefish Comm Board, I was planning on laying the LED strip on its side. Well, after digging into addressable LED strips, I quickly learned that this option was not going to work.

Laying the strip on its side would give me better LED resolution (spacing between the LEDs), but I could never figure out which LED I was trying to program, as opposed to laying it out flat. Also, rolled up, I could not fill in the entire display area, as I was limited by the angle that I could bend the strip.

I decided that I would cut the strips and connect them together, so that they could be laid out flat. The LED resolution would not be as good, but at least I could keep the project moving.

By the way, if you plan to buy LED strips, know that not all of them are addressable/programmable. Some just flash, which unfortunately I bought first. No biggie, as I am using this strip to practice cutting and splicing.

The strip on the left is the non-programmable – only flashes. The strip on the right is programmable via a micro controller (Arduino Board – or others) and a computer.

Cutting and splicing LED strips is not that easy – just my opinion. I was not able to solder the strips together with discrete wires, but found some connector clips on line, shown below. They worked pretty well.

The picture below shows sample strips laid flat. This is how the entire cuttlefish display area will look. Each yellow square is a multi color LED. The splicing connectors will be behind the display area.

I’m going to lay this out so I can play around with the programming. I am not happy with the resolution, but after thinking a bit more I decided to ultimately go with an LED display board, as shown in this picture.

This is a 16 x 32 LED display, which I should be able to control using my Arduino PCB (at least the literature said it would work).

This will give me 512 LEDs, good resolution, variable colors, and I can make them appear as a moving wave. This is really much more like the chromatophore cells on the cuttlefish skin. Should be cool!

My display area is smaller (due to the size of the LED board, but that is an easy fix. I’ll just make the cuttlefish display area a bit smaller.

Now if I just knew how to program in C++. Okay, more to learn.

Transistor Radio Repair

Posted on by

Until a couple of months ago, this 1961 transistor radio had worked flawlessly. Now all I could hear was static.

Since this is one of the few items that I’ve had since childhood, I decided that I needed to perform a repair.

Other than the battery, the most likely issues are: 1) the ‘potentiometer’ for on-off / volume control is dirty; 2) the ‘variable capacitor’ for station tuning is dirty; or 3) an ‘electrolytic capacitor’ on the circuit board has dried out.

The Potentiometer, located just behind the white on-off / volume control (at the top of the radio), gets dirty over time.

Potentiometers, also known as variable resistors, have a small wiper that moves across a resistive surface. This surface gets dirty and needs to be cleaned to operate properly.

The Variable Capacitor, located behind the larger white adjustment wheel, is part of the tuning circuit. It can also become dirty over time.

The variable capacitor acts to vary the capacitance (or electronic charge) by moving plates within the component, as the tuning wheel is adjusted.

An Electrolytic Capacitor holds a charge, essentially like a small in-circuit battery. As they age, they dry out and require replacement.

I doubted that it was the battery, but since it is the easiest thing to try, I replaced it. Same issue – just static.

To proceed with the repair, I needed to remove the circuit board from the radio case. However, there was a slight problem. The earphone jack had a nut on it that required a special tool – a spanner wrench. Of course, I do not have any spanner wrenches.

I tried a small screw driver, pushing on one of the slots in the nut, but it did not even budge. I certainly did not want to crack the vintage plastic.

After two hardware store visits, I still did not have a spanner wrench that would fit the nut.

If I couldn’t buy it, then why not fabricate one. I used a paint can key and filed it down, until I had two small tips that fit exactly in the two slots on the nut. It worked perfectly!

With the circuit board out, I performed a quick inspection of all the electrical components. Everything looked good. No obvious signs of heat damage or capacitor leakage.

The next easiest step was to clean the poteniometer and variable capacitor. I used some electronic spray cleaner.

I simply sprayed a little behind each white adjustment wheel, and then turned them back and forth about ten times. I do not suggest that this is the best or only method, but it’s what I did.

Time to test to see if the cleaning worked. I reinstalled the battery, and turned on the power with volume up. I adjusted the tuning wheel and… the radio is now fixed. It sounds great too!

Just in time to listen to the World Series… just like I did in 1961.