Voltlog #93 – Bluetooth Receiver Weekend Update

This week I build a DIY bluetooth 4.0 audio receiver. I used the CSR8635 bluetooth module, a recycled lithium battery cell that I got out of an old laptop, a TP4056 battery charging & protection IC and a DIY PCB I made myself.

Here are links to these items if you plan to build one yourself:

Or you can just buy a ready-made bluetooth receiver.


Voltlog #78 – 2x25W Bluetooth 4.1 Stereo Amplifier TDA7492P

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:

Wiring diagram below:

Voltlog #47 – ICL8038 Frequency Generator Kit Assembly

Today we’re going to be assembling this frequency generator kit based on the ICL8038 which I got in an earlier InTheMail episode. The ICL8038 waveform generator is a monolithic integrated circuit capable of producing high accuracy sine, square, triangular, sawtooth and pulse waveforms with a minimum of external components.

Voltlog #45 – Multiple Rail Power Supply Kit Assembly

In this video I am assembling a multiple fixed rail power supply kit. This power supply works with a 5-24V input either through a USB mini socket or a dc barrel jack (2.5mm center positive) and at the output you get +12V, -12V, +5V, -5V and +3.3V. My kit was missing 1 small heatsink and one of the electrolytics was a different value than specified on the PCB.

Voltlog #42 – DIY 4 x 18650 Battery Charger

Today we’re going to be making a DIY lithium battery charger and more specifically aimed at charging 18650 cells. I sometimes take apart some of these laptop batteries to recover 18650 cells and I have a bunch so far that I kept. Every-time I salvage these cells I test them before deciding to keep them or not.

As you can imagine it takes time and I need to charge multiple cells at once. So I will be making a charger that can handle 4 x 18650 cells but the project is scalable and you can increase or decrease the number of cells it can handle according to your needs. As usual, links for all the items will be in the video description.