Saturday, August 16, 2014

Headphone Bass Booster

This is what I've come with this time, the main electronic project this summer.

What we have here is a bass booster device for headphones. It amplifies a range of signals that you can choose with the potentiometer on top. Although you can also boost high frequencies with this, it is intended to amplify low ones which are which mobile phones and MP4 players lacks.

This is the thing out of the box. Each PCB deal with one channel.

The diagram is from somewhere in Makezine, but I modified it to suit my preferences and for improving it a little bit. Mainly, as I didn't want it to be portable, and I hate batteries, I fed it with a wall adapter. I don't want to go too deep into electronic matters, but for this you have to get some adapter rated with more voltage than what you need (I chose 9V), then regulate and filter at the same time with a LM7805 to avoid noises. I made some other changes too.

The thing is based on a LM386. The green wired PCB is right channel.

The result is great. I was worried because when you work with sound stuff you get annoying noises very easily, an as I'm sort of an audiophile, I can't listen to music with a noisy machine. It would have gone straight to the bin if that happened. But fortunately I get absolutely no noise from it!, just pure sound!

Besides it boosts a selected range of frequencies, it also amplifies noticeably the sound in general. Nevertheless, as it's not its purpose, I haven't measured what amount.

I added a nice yellow LED and fitted it into a box with a transparent cover.

I'm very happy with this little thing. I reckon it'll be very useful. For me, it's not about simply using this and there it is. I think the greatness comes when you set up properly an equalizer to manage all the frequencies, then with this extra boost in low ones you'll get a very nice sound.


I want to show it to you the best I can, so I've made a video where I play with the potentiometer. The audio (courtesy of Evanescence) is recorded through the computer so you can listen better. I promise it's not altered in any way, I've turned off all the equalizers.

Nice project.

Friday, August 15, 2014

Multilayer Printed Circuit Board

The other day I wanted to reuse some parts from a broken computer motherboard. I didn't want to try desoldering because I knew motherboards are multilayer PCBs, extremely difficult to solder or desolder on them. As I only wanted the audio ports, on the edge, I cut them. Easy.

After taking a look at my rubbish cutting work I though it would be perfect for showing you how multilayer PCBs are inside.

It is very difficult to find on the Internet (I haven't been able) clear pictures or simply some pictures like these ones, so enjoy.

Click to make them larger.

 You might think this particular board is thicker than others, but it's just an effect for this much zoom. It actually is 1.5 mm thick.

You can see those copper layers. There are at least 6 or 7! Mad.