Testing the Sound Switcher board with an Arduino

So after completing my Sound Switcher board (and updating it) I wanted to use it with a microcontroller. I have a couple of aux cables lying around and some headphones to hear what is coming out of the board. Using headphones though is not ideal as it will hurt my ears after some time, as writing and testing the Arduino sketch is going to take some time. Last night I found a self powered speaker so I will use that instead (it was only $5 so worth it, and even some decent sound coming from it). Here it is:

Self Powered mini speaker

Yes, it does look like a microphone but it is actually a small speaker. It's quite ingenious, I took it apart and looked at it (forgot to take pictures) and the cool part is that it charges using the same 3.5mm input. Not
ideal if you want to listen to it and charge it at the same time but still, quite portable.

Soft switch sound switcher using a few 2N3904 and resistors

Having two sound sources connected to the same output may be good for a while but sometimes you don't want to have both sources outputting sound at the same time and may want to switch between them. I wanted to be able to control this with a micro controller and not use a servo, so a mechanical switch is out of the question.

Transistor as switch

I know that you can use transistor as soft switches so I started researching how to build this.

Using LM317T to simulate LIPO battery

I have a few battery operated devices (rechargeable) that I wouldn't mind using only connected to a power source. So I started to find a way to replace a LIPO cell with a power supply. The first (and easiest) answer to this problem is using a LM317 as a power source.

Typical LM317T usage circuit

So I started looking around for how I might build a circuit. I found a lot of information online and started building it. Before this, I still needed to know what the needed voltage is. A standard LIPO cell is rated at 3.7V.

Power Small FINISHED projects from USB

Often I create a small... thing, not really anything to write home about but something that blinks a LED for example and I use and Arduino to power it. This is good for the building stages but using and Arduino just for the 5V output is not efficient.
So I wanted a way to power the devices from USB 5V. this is bad for the laptop health if the project is not finished and there are still problems with the wiring but when all is finished, you can safely source the needed voltage from a PC (remember no more than 500 ma).
My solution is a power cable with a USB male on one end and standard header pins on the other.

Small UPS for RaspberryPi

Some time ago I went into Radio Shack and found a small USB rechargeable battery that has a retractable USB connector on one end and a microUSB on the other. It looks something like this but it is only 800 mah and was on sale for $8.

I wanted to use it as a power source for my RaspberryPi but wanted it to use the battery only when mains where off. I looked around for circuits that allowed for instant swithcing between 2 power sources and actually found something I could make but it was pretty complicated.

Upgrading HP Compaq 6715s with a Motorola Surfboard SBG6580 wireless card

So after pulling apart the dead modem/router I wanted to use the only working part scavenged.

I opened my wife's laptop to access the wi-fi card. This is the easy part as it is just one screw for the panel and 2 screws that hold the wi-fi card in place.

HP Compaq 6715s back

HP Compaq 6715s panel that contains the Wi-Fi

A close up of the old WLAN card

The first problem appeared:

HP Compaq 6715s new WLAN installed

Motorola Surfboard SBG6580... to pieces and beyond

So this year did not start well for me. When I finally woke up on the 2nd of January my internet kept going down on me. After numerous restarts and resets of my wonderful modem/router combo it died. The top 3 lights would flash for a sec and then nothing. That is the last time I buy one of these all-in-ones (on a side note, don't get the Belkin wireless router it restarts every time you change any settings).

Anyway here is what I found inside it:

A main board with a mini PCI Express slot.

Front of main board

and the other side

Back of main board