USB Power Meters

USB Power Meter

Handy little devices. They help you debug a lot of things specific to the USB Power outputs. It tells you what the voltage and current draw is from a particular power source. It helps figure out multiple things regarding the system-as-a-whole like, Is the power source capable of delivering a voltage at a particular current flow or is the USB port dropping the voltage at higher currents? Or Is the cable you are using good enough(You can know this by estimating voltage drop at both ends of the cable with the device).

USB Power Meter
USB Power Meter
USB Power Meter

The pics show the multiple types of these power meters available. The first thing you need to make sure of is, What type of port termination it provides(Type-A or Type-C) and what USB type they support USB2.0 or 3.0+? This is very important as the shape of the ports wouldn’t tell you what USB Mode you have. (Eg. You can have a Type-A port with USB2.0 only or with USB 3.0 compatibility). If you are into USB C and power delivery applications make sure the voltage and current ratings of the meter you buy supports it. For eg., the UT658Dual Model power meter has Type A(USB2.0) and TypeC(USB3.0) ports on both ends. Now if you want to interface it with a Type A USB 3.0 port the device just wouldn’t support it. Similarly, UT658B Model has a USB 2.0 Type Port only.

The awesome thing about these devices is that you can use them as a charge meter to estimate the battery capacity of devices. These keep a running count of the reading so that you can kind of figure out what is the approx battery capacity in a device. Also can be used to estimate how much time it will take for large power banks to finish charging if you keep looking at the current draw(The current draw tapers off for LiPo charging towards the end).

All in all a very versatile little tool. A must-have unit as these ones are relatively cheap nowadays. Buy quality ones, there are quite a lot of cheap ones around.

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Headphone Volume Control DIY Fix

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A post shared by Amaldev Venugopal (@amaldev.000)

In these days of wireless headphones, I am still a fan of wired ones because of their longevity and not having to recharge them every couple of days(Also after a few hundred charge cycles, the battery loses its capacity). I like the ones with a built-in microphone and slider volume control. Usually, after a year or so of its use, most wired headphones would have the problem of mismatched sound on both ears and when the volume slider is moved, there is always poor volume progression, followed by sound cracking.

Mechanical sliders inline in your headphones are resistance potentiometers that have a wiper arm changing the resistance when you move the knob. What happens after some amount of use is that the wiper contacts get dirty and the resistance values won’t increase gradually. It makes contact only at certain points(Hence the cracking/popping sounds).

A quick fix to this problem which always seems to work for me is to take a high-quality Isopropyl Alcohol(IPA 90%+ concentration) and spray down the contacts. If there is a chance for you to open the plastic enclosure it will be great to open and clean it. Most of the time as shown in the video, it will be ultrasonically welded and you won’t be able to open it without breaking it. In that case, find a small opening next to the slider and spray the IPA. Make sure you move the sliders back and forth quickly a few times to properly clean the contacts. That should fix your problem. Good quality IPA evaporates fast and won’t leave any residue.

PS: Don’t use any oil-based lubricants for this if you can’t find IPA as it will damage your carbon film potentiometers. Another alternative is to get professional-grade electrical contact cleaners.

Happy Listening. 🙂

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