Seeking Proposals for Capacitor, Inductor or Resistor Projects

Having worked at a capacitor company, I can suggest projects like these where the caps are, relatively speaking, critical. Or at least, they are not an after-thought.

Power Banks

Sometimes these are called "hold-up" circuits. Situations that require a large bank, or reserve, of energy but batteries, are not suitable. A common one is

UPSes (uninterrupted power supplies) which may have large banks of aluminum electrolytic or supercapacitors that provide energy until the batteries can start supplying it. SSDs are another one. SSD drives generally have large capacitor banks so that their TOC can be flushed to flash memory when the rails drop.

Variable Frequency Drives

With the popularity of electric vehicles, "DC Link" capacitors have been popular as well. In a motor drive (or inverter, or VFD) you typically have an incoming voltage and frequency (aka supply) with an output voltage and frequency (aka output). In between are inverters to convert the incoming AC (if it is AC) to DC and then the output stage is DC to AC. That conversion allows for changing the output's voltage and frequency. In between the stage sits huge capacitors. For electric vehicles, windmills, and solar panels this can be 10s of thousands of microfarads. But any situation where you are driving something with variable speed, you need a capacitor for more than just "decoupling."

IoT / Harvesting

On the smaller end of the scale are IoT devices. In this case, I mean the types that harvest energy from the environment. They might include a piezo element that captures energy from vibration. Or, more commonly, solar panels. Storing that energy in a battery is sometimes costly, regarding power, because of the electrochemical process. So instead, energy is stored in a capacitor. The challenge here is designing a capacitor bank that has very low leakage. (In this situation, ceramics are good, (wet) aluminum electrolytics are not.)

Switched Capacitor Power Supply

An idea that keeps floating around power supply engineers is to eliminate inductors by using a "switched capacitor" design. It might be interesting to look at a DC-DC converter for a project like a small robot (something with high current motors and relatively high current microcontroller). You could build a traditional inductor based DC-DC converter as well as a switched capacitor design to compare efficiency, size, cost, etc.

Just a few to think about. Hopefully, someone can build something more creative on top of those.

Hi James,

I was looking over your ideas. I'm most interested in your suggestion of a switched capacitor power supply. I specially interested in charge pumps. I don't recall any discussions and/or projects revolving around this type of circuit so it could be a good learning experience for the community. I'm thinking about  "A Tutorial on charge Pumps," including building some variants.

From your blog, I got the impression you just offered the idea.

Would you mind if I opened up this project to the community if you were not going to pursue this idea otherwise?

Randall

Hi James,

I was looking over your ideas. I'm most interested in your suggestion of a switched capacitor power supply. I specially interested in charge pumps. I don't recall any discussions and/or projects revolving around this type of circuit so it could be a good learning experience for the community. I'm thinking about  "A Tutorial on charge Pumps," including building some variants.

From your blog, I got the impression you just offered the idea.

Would you mind if I opened up this project to the community if you were not going to pursue this idea otherwise?

Randall