Improving Terrible Products with $0.50 Components

While maker tech like development boards help us build devices with more ease than ever before, true electrical engineering is still a complex task that requires real expertise. If, for example, you design a custom PCB and fail to used filled ground planes, you may end up with EM noise in your signals. Those things are tricky and the engineers designing low-cost devices often fail to account for them, resulting in products that fail to perform at an acceptable level. YouTuber GreatScott! found many such devices among the offerings at AliExpress, but determined that many could be improved with a simple $0.50 component.

Every electronic device contains at least some analog circuitry. Even a purely digital device requires power, which is analog. That digital device could, for instance, use the power source as a reference voltage for making comparisons to determine if a signal is high or low — the fundamental comparison at the root of all digital logic. If the power input is dirty enough and there isn't any component to compensate, then those comparisons become ambiguous and the logic can fail to operate as intended. This is an insidious problem, because it isn't always apparent. It may present as an intermittent issue that is very hard to identify.

The most common way to clean up a dirty power input is with a capacitor. Capacitors take in power to charge up, then release that power at a consistent rate. That's helpful even for something constant, like a power source. It will take the peaks and valleys that make up dirty power and smooth them out into something more clean and consistent.

That's how Great Scott! was able to improve cheap AliExpress products. Either because of poor engineering or simple cost-cutting measures, many of those products omit capacitors on the power lines and produce unpredictable results. By adding the proper capacitors, which only cost around $0.50, Great Scott! was able to create cleaner power that helped the devices perform better.

This is a simple and affordable fix that will work with a wide range of devices — but it isn't magic that will fix everything. Sometimes the issue isn't as simple as dirty power and so the addition of a capacitor won't help. But if you have an oscilloscope, you can use the same technique as Great Scott! to determine if a capacitor would solve your problems.