Category Archives: Voltage Converter

Fix: Samsung Galaxy S3 not charging, charges slowly or charge toggles on and off

s3-charging-smallPretty soon after I bought my brand new Samsung Galaxy S3, it began to be erratic charging behavior. It would often not charge, charge slowly or rapidly switch/toggle between charging and not charging. Searching on the web didn’t yield any good solutions, with most sites arguing about whether the cable, phone, or software was to blame.

The charging cable seemed suspect, since it would work better sometimes if I manually held it at a particular angle. However, even if I used a brand new cable, our car’s USB cable or my wife’s cable (which was still working for her S3), my phone had this problem. After a few months, my wife’s Galaxy S3 started having the same problem. Continue reading Fix: Samsung Galaxy S3 not charging, charges slowly or charge toggles on and off

How to fix: Pantech Jest battery will not charge

My wife’s new Pantech Jest cell phone won’t charge its battery. This has been a recurring problem with new batteries we get for it, too: inevitably it always ends up refusing to charge the battery. If you plug the phone in to charge then the phone will turn on and power up, but it will not give any indication of charging. Then no matter how long it is plugged in, the moment the phone gets unplugged it instantly turns off. The first time this happened our wireless provider replaced the phone, but the new phone exhibited the exact same behavior right out of the box. This meant that the battery was at fault, not the phone, so then our wireless provider replaced the battery which did fix the problem. However, a few weeks later the exact same thing happened. So they gave us another replacement battery (which fixed the problem again). But now this week the same problem has happened a third time. Fortunately there is a solution. Continue reading How to fix: Pantech Jest battery will not charge

DC-DC switching voltage regulator: Buck converter

Power MOSFETWhen I took a power electronics course at MIT (6.334) almost two years ago I instantly fell in love with the simplicity and ubiquity of switching power supplies. They are so simple and interesting that I decided to devote a few posts here describing how they work. Voltage regulators are interesting and useful to learn about because they are used everywhere. Electronic components (for example, those within your home electronics equipment) often require different voltages, so voltage regulators included in the equipment to generate those voltages. The first question to answer in this post is “What is a voltage regulator”: Continue reading DC-DC switching voltage regulator: Buck converter

Convert 120 V AC to 3.3 V DC without a transformer

I finally made some progress with the AC to DC converter (without using a transformer.) I recently graduated from NAU and got a job, so I actually have a little more time on my hands to work on stuff like this (even with a 3-month old baby.) If you will remember from my previous post on this topic, the challenges facing this project are that it should convert 120 V AC to 3.3 or 5 V DC, handle a relatively high output current (more than 15 mA, and the more the better), have a small profile (so no transformer or huge capacitor,) and draw very little current when no load is attached. Continue reading Convert 120 V AC to 3.3 V DC without a transformer

Small AC-DC converter

One of my goals recently has been to make a small (no transformers) application-specific AC-DC converter. Here are the specs I need to meet:

  • Iout > 15 mA (DC)
  • 3.0 V < Vout < 32.0 V (DC)

The reason I was planning for these specs is because I am testing my converter with a solid state relay (SSR) that is driven by a DC input of 3 V, 15 mA minimum, and connects an AC load of up to 240 V, 10 A maximum. I am trying to keep the power consumption of my circuit down, so that means I need to try to keep both the voltage and current as low as possible. Here are some of the paths I may try to take: Continue reading Small AC-DC converter