Outlet 60 Minute Timer

Outlet 60 Minute Timer

As I was browsing reddit today, I found this nice simple project, an Outlet Timer. I remember leaving the hot glue gun on one day, and finding it the next day, still running as hot as could be. The glue that came out of it was orange, and I know that things would have been bad if I didn’t catch it when I did. Typically I try to be as cheap as possible, but for the importance of this project, I didn’t mind investing the $27.

Here are the parts that I used for this Outlet Timer

In true DIY fashion, I’ll go through the steps that i used to make it.  I first wanted to find out which wire was Hot (the conductor that is switched when you switch on/off the power strip.  I first pealed back the insulation, being careful not to nick any of the wires.  I picked this location so that it was pretty close to the strip.

Under the insulation, we find, 3 wires (white, black, green).

In my case, the switch was connected to the black conductor (I could tell by measuring the conductance between the black wire, and that socket, when I switched on/off the power strip).  I cut the wires, with a pair of wire cutters, and stripped the recommended length of conductor for the countdown switch.  After feeding both wires through the 1 Gang electrical box, I inserted the trimmed black conductor into the countdown switch.

Inserting Black wire into countdown switch, note that both ends of the power cord have already been fed through the 1 Gang electrical box.

After that, I secured both green wires together using a WireTwist wire connector, and I did the same for the white wires.

Securing green and white conductors with wire connectors

At this point, I wanted some strain relief, so that things don’t come undone if someone accidentally pulls the power strip.  So I took 2 black zipties, and fed it through the 1 Gang electrical box so that the power cable will be secure against the box.

Stress relieving the power cable using zipties

By far the hardest part of this project was screwing the Countdown switch to the 1 Gang electrical box.  Those flat-head screws weren’t fun.  I wrapped it up by putting the faceplate on.  I did a quick sanity check, by using my multimeter and checking conductance before it has been plugged in.  Ground and Neutral were always connected, Hot was only connected to the wall if both the timer was on, and the switch for the power strip was on.  I tested it using my plug tester, and it tested out 🙂

Price list

As always, proceed at your own risk.  If you make this project, and it messes up, you take full responsibility.

Outlet 60 Minute Timer

Cheap Breadboard Arduino with Wireless Module

I see that there is a good amount of demand in the community for a cheap “Arduino” clone with wireless. Many people, while grateful of the Arduino community and organizers, are frustrated, because everything seems so darn’ expensive! $30 Arduino Board + $20 wireless thing + $15 proto board makes almost $100 just to get you running. If you somehow found JeeNodes, they are $23. A RBBB, which just has the processor, is $13. We can do better than that though!

If you’ve clicked on the caption, you’ll see that it is possible to make a breadboard Arduino for just $7. The problem is that we still need a wireless module. XBee’s retail for $23, which is a pretty robust solution (configurable up to 19200 baud in real world situations, can communicate just with serial, standard footprint so there are lots of cheap adapters for it). But it’s expensive. You can check out the RF Bee, which is a $20 wireless solution, which actually contains an Atmega168 (running Arduino)! It’s tiny form factor is awesome, but it is $20. A RFM12B radio retails for about $6, which is pretty decent. It even has a good library for Arduino to go with it. But we can do better.

How about a $2.50 wireless module, that has a good library to go with it? That would bring our cost to $9.50, excluding shipping. That’s my cup of coffee. The hard part is finding the individual components you need, which I will help you out. Finding the cheapest parts from 20 different places is great, but the shipping will kill you. I’ll attempt to minimize the shipping cost, by ordering from a few places, getting what we need from each.



That brings the total for the required parts to $5.44…  wow.  Shipping would be about $5 from each place (roughly), but it isn’t included in our consideration.  Getting some different colored wire wrapping wire will help you out a lot, as well as getting a wire wrapping tool (which can be very useful).  Adding the $2.50 wireless module would bring you to $8, pretty nice!  This number scales down as you buy more, so if you buy enough parts to build 3 or 5 of them, it will be cheaper. Consider the pricing levels of the ATmega328p chips to figure out how many you should buy (you should always get spare protoboards 😛 )

I’ll do a post sometime soon on my recommended set of parts to have.  A quick update on the Carduino: I still haven’t put it in, I need to get up the motivation to start modifying wires and integrating it into my car.  I know eventually I’ll get to it, but in the mean time, I’m exploring the idea of making my own Watt Meter, with SD logging.  It would be hard to compete with that, but if I’m smart, I can end up with a meter that can work in RV’s, like this one does, using an external Shunt (small value, high wattage, precision resistor).  Till then!

Edit:  If I could make a schematic for this cheap Arduino breadboard, I would take the parts required to make it work, and customize it for each application after it.  The arduino is great as a platform, but for completed projects, typically the soldering connection is constant.    Here is a quick guide on wiring up the nRF24L01+ to a Arduino.  By following the Instructables post, you can get a general idea of how to wire it up.  I got the idea for the voltage regulator + resonator from JeeLabs, so the v5 schematic would be what you use to wire up the rest of it.  I hope this helps!