It all started a few days ago when I was talking with a friend and he suggested, since we do most of our phone charging at night, why not charge them at a lower rate for increase battery life. As you may know, when you increase the charging current, charging happens faster at the expense of losing battery life over time, you get fewer battery cycles before it starts losing its capacity.
So I decided to build this small gadget, that goes between the usb output of my charger and the usb plug from my charging cable. In my case I have an Iphone and the charging current can be limited to 500mA by having a set of resistors on the USB data lines.
Links for the parts used to build the project:
In this episode I am building an analog adjustable dc load with parts easily obtainable from ebay and banggood. The advantage of such a dc load is that you can understand how it works, modify or repair it if necessary far easier than you would with a digital one. I was able to push mine up to 60W dissipation, but it is recommend to stay under 50W to protect the mosfet.
Here is a list with links to the parts used in this project:
- Constant Current Analog DC Load PCB Module XHDZ-FZ-2D
- PZEM-031 100V 20A LCD Panel Meter
- Metal Enclosure 170mm x 130mm x 75mm Blue
- 10 Turn 10K Potentiometer
- Brass Standoffs Kit
- M3 Screw Kit
- KSD9700 NO Thermal Switch
- Cooling Fan 12V
- JST XH 2.54mm 3 Pin Connector
- 4mm Banana Plug High Current M5
- 2.1mm DC Jack Panel Mount
- Rocker Switch
- Screw Terminal 3 Pin
- 16AWG Silicone Flexible Wire
In this episode we are going to build a bluetooth speaker amplifier based on the TDA7492P class D audio amplifier coupled with a Bluetooth 4 module. We are not actually going to build the amplifier module because we can get that from China, very affordable, it only costs around $12 shipped which is way less that it would cost us to buy the bluetooth module and the TDA7492P individually not to mention the cost of fabricating a PCB of this size.
So we are actually going to use this module and build the final product with a nice enclosure and a suitable external power supply
Here are some links for the parts used to build this project:
- Bluetooth Audio Amplifier With Enclosure TDA7492P
- Bluetooth Audio Amplifier PCB Module TDA7492P
- Switching Power Supply Brick 24V 3A
- Aluminium Enclosure 110x66x24
- DC Power Jack Panel Mount
- 3.5mm Stereo Jack Panel Mount
- 4 Way Speaker Terminal
- Mini Rocker Switch On/Off 3A
- 100x100x0.5mm Thermal Silicone Pad
- 20x20x15 Aluminium Heatsink
- Countersunk Screw 3x6mm
- Brass Standoffs Kit
- Self Adhesive Rubber Feet
Wiring diagram below:
This is the first AC-DC power supply that I’m designing and building. Everything seems to work up to a point where the chip (TNY 276 from Power Integration) gets too hot and enters thermal protection. This is where I’m asking my viewers help to jump in with suggestions on what might be wrong.
This is part 2 where I get the circuit working by switching from the TNY276 to the TNY277 which has a higher power rating and is probably the proper IC to use with this transformer (EE1616 ER2741)
And this is part 3 of the video where I finally find the real fault in the circuit. It turns out I was right, this circuit should have worked with the TNY276 as well and it wasn’t the higher power rating of the TNY277 that fixed the issue.
A while ago I saw this touch musical keyboard kit on banggood and it seemed interesting enough to order one. It turns out the kit is using a single atmega8 to do all the touch sensing (8 ch) and play the tunes accordingly. Although not very useful for me it sure was fun to assemble and play with.
Got this cheap power socket with usb charging ports from ebay. I don’t plan to use it, I was only curious about the quality of the power supply inside.
Sometimes, when I have some spare time I like assembling these cheap kits coming from China. Today I am assembling an LM317 adjustable power supply kit complete with voltmeter. Unfortunately they sent me a wrong resistor value so the kit didn’t work as expected but I was able to fix it in the end.
A while ago I watched a video from Scullcom Hobby Electronics channel where he build a precision current source, a very simple but accurate one. If you don’t know this channel I encourage you to subscribe to it, it has allot of nice videos on lab equipment either building DIY versions or reviewing existing ones. Each video has nice drawings and the guy clearly knows what he is talking about so a great resource for learning.
I don’t have any current source in my lab, and these are useful for testing multimeters for example. I was looking on ebay for a current source but I wasn’t able to find an affordable one so I’ve decided to build one using the project information from that video and I will link the video in the description below, it’s nice to watch it has lots of interesting explanations so I won’t repeat them in this video, I will mostly focus on showing you how I build and improved my current source.