Category: DIY

This category will hold everything DIY related.

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 #72 – DIY AC-DC Off-Line Converter With TNY276/TNY277

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.

Voltlog #71 – Electronic Touch Musical Keyboard Kit

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.

Voltlog #69 – LM317 Kit Assembly Fail

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.

Voltlog #67 – Precision Current Reference Using REF200

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.

Voltlog #64 – DIY Adjustable Power Supply With Enclosure

Today I’m going to be building a complete DIY analog bench power supply. The actual analog power supply kit (0-30V 0-3A) that I’m going to be using, is this one, it was shown and assembled in voltlog #8. Besides that I’m going to be using this plastic enclosure which I think is quite nice and perfect for such a project, this one can also be found on banggood and there will be links in the description for all the items used in this build.

Voltlog #62 – Rigol DS1054Z Fan Replacement

Everybody knows this is a great scope for the money but as usual test equipment doesn’t use the best solutions in terms of cooling fans and associated hardware. They care mostly about keeping the unit cool and not about the noise the unit makes because usually these are used in environments where multiple equipment is run at the same time, the noise level is already high so it doesn’t matter much if a small 50mm fan is adding noise.

But it’s a totally different story for us hobbyists that are using these pieces of test equipment indoor, in our homes. We usually want units with passive cooling or with silent fans.