Today is
March 26th
Circuit Board

This section gives some basic electronics and robotics information along with helpful links. I also detail a lot of my projects. For most of them I've included schematics. I use ExpressSCH for drawing them and ExpressPCB for designing circuit boards. They are a free package from You can download for free and get your boards professionally manufactured for very reasonable prices. Of course, with the final layout you can also etch your own boards at home if you choose.

March 24, 2011

Motion Detector Cat Fountain

My cat, Murray, prefers to drink from a trickle of water in the bathroom sink. That's not always convenient for either of us, so I decided to modify a cat fountain for him.

Cat Fountain
This is the original fountain, a Drinkwell Platinum. It has a large reservoir and a pump that creates a constant stream of flowing water.

"But I'm not always thirsty. Why leave the pump running all the time? Wouldn't it be better to have it motion activated whenever I wanted a drink?"

I searched the internet and found a nice, small passive infared motion detector module from Glolab. This would fit perfectly. The pump came with a 12 volt AC transformer, but I needed to change it to DC for the detector with a bridge rectifier.

Power Plug
In order to hook the power to the circuit board I cut off the existing connector and replaced it with a Molex KK connector.

Here is the project on my breadboard. The red amd white jumper wires simulate where the pump would be connected. The PIR triggers a solid state relay, AQH2213. (The schematic shows AQH3213 but Digikey was out when I ordered) Everything worked great, so time to build.

The PIR will be mounted in the front of the dish, inside a space between the actual water dish and the fountain frame. It simply pokes out through a 3/8 inch hole and is hot glued into place. The wires go back to where the circuit board will be mounted in a similar void. They end in a 3 pin header for easy connection to the circuit board.

Here you can see the void where the circuit board will be mounted, the 3 pin header coming from the PIR, and the Molex KK connector I attached to the pump wires.

Circuit Board
Here is the circuit board wired up and ready to be mounted via the 1 inch standoffs. There are only 3 due to the curve in the fountain frame, but that's more than enough to hold the small board in place.

"Hey, that's better. Watching you do all that work made me thirsty. Let me try out my new fountain".

Here's a video that shows the fountain in action. You can also see where the PIR is mounted.

Other Projects
My second microcontroller project - June 18, 2011
An audio controlled servo - June 1, 2011
My first microcontroller project - May 17, 2011
A 555 timer project - December 17, 2009
A basic line-following robot - March 11, 2009