Time Delay Relay

Time Delay Relay

I’m working on a project that requires two power strips to be turned on in a sequence. The first power strip powers 6 HDMI displays, and the second one powers 6 computers. The displays have to be on before the computers so they sync properly and get the correct resolution. Since I can’t rely on a person to do this properly, automation is the answer.

My first thought was to use something like a PowerSwitch Tail with a microcontroller to trigger it. (There’s also a cheaper kit version available.) The issue with this solution is that I’d need a microcontroller, and a power supply for the microcontroller, which are more parts, and more points of failure, and take up more space. I also considered using a cheap relay module, but ultimately I was overly complicating the whole thing. Also, I want this to be reliable, and sticking a 5v power supply, a microcontroller, and a relay in a box for three years seemed a little risky.

What I really needed was a “Time Delay Relay” which is a device that can get power, wait X number of seconds, and then power on another thing. There’s a whole bunch of them you can just buy! Time Delay Relays are not cheap though… This one is under $40, but you’ll probably also want the socket, which puts you closer to $50.

Luckily, Milwaukee Makerspace is filled with all sorts of old industrial “junk” and we have a bunch of these sitting on a shelf! Brant (you know, the guy who made a Auto-Off Timed Outlets from an old microwave control panel) helped me find one and get it wired up last week. It works great!

I used a $3 extension cord to provide an easy way to plug it into the first power strip and plug the second power strip into it. There’s a dial that lets you set the delay up to 10 seconds, which is more than enough for my needs.

Time Delay Relay

If I’ve learned anything from this project it’s that even though you think you might have a good solution to a problem, it’s still worth asking others (at the space or on the mailing list) because you may get a better solution, and may even get the parts you need.

Auto-Off Timed Outlets

If you’re like me, you’ve left a soldering iron plugged in once or twice.  Hopefully you’re also lucky like me and it’s never started a fire.   Occasionally I’ll grab something off our Hack Rack and take it apart.  A) It’s fun and B) it helps cut down on the ever-growing pile of appliances in the East Room.  Recently I focused my efforts on a microwave oven.  During my salvage operation I managed to extract one plastic fan, two thermal cutout switches, a transformer, the magnetron, a huge capacitor, and the controls.  I soon realized that what I had in front of me was a digital timer wired to a normally open relay.  I couldn’t immediately think of something to do with it, but it seemed too good to toss or disassemble further.  About a week later I decided to wire it to a pair of 120-volt receptacles.  Voila.  Any appliance with a standard plug can be set to run from 00:01 to 99:99 before powering off.  Just press “TIME COOK” then enter the time in minutes and seconds, then start.  The relay closes the circuit and the outlets are energized.  When the timer runs out, a piezo buzzes and the outlets shut off.  The relay on the microwave’s circuit board is 120-250 volt at 16 amps, so I’m fairly comfortable it will handle one or two 40-watt soldering irons.



Video Wall of Terror

This weekend, I helped decorate for a Halloween Party at my sister’s house. There’s an odd hallway that connects their main large public room to the rest of the house. It’s used for storage, and has shelves on both sides.

This year, I decided to decorate that area by creating a video wall effect. Something like a Television Control Room of Terror!

To start with, I simply filmed my brother-in-law with a video camera – only from WAY TOO CLOSE! I shot macro video of his eye and mouth. Then I edited the footage to create a custom looping DVD.

In the hallway, I set up multiple monitors. These are old monochrome standard definition monitors that were on their way to the recycling center. They were professional monitors, which means that they can pass a video signal through from one monitor to another, making it easy to daisy chain several monitors.

Next to the monitors, I set up three DVD players (including one car DVD player – hey I use what I got!) to play the three different custom DVDs – Right Eye, Left Eye, and Mouth. Each of the three videos is a different length, so they will continue to drift out of sync. That way, as they loop, the visuals are a continuingly changing experience through the whole evening.

Above the monitors, I set up a video camera on a tripod and fed it to some of the monitors. That way, when party-goers look at the monitor, they also see themselves. Having feedback on some of the monitors adds a sense of interactivity to the project.

After the monitors and DVD players were all set up, I covered the rest of the shelving with black paper. In a dark hallway, lit only be black lights, it’s a great effect of creepy images floating in the hall.

If you want more details on this project, I made a full step-by-step write-up on Instructables.

$5 Upcycled Desk Clock

Last summer I came across a collection of car parts at a garage sale; instrument clusters, lights, gauges, and some digital clock displays.  For $5, I became the proud owner of a JECO Japan, vacuum fluorescent clock display.  The plastic housing held all the clock electronics, membrane buttons for setting the time, and a four-pin connector.  After powering it up, I realized one of the pins could be used to dim the display, which is a pretty nice feature to have.

I’ve worked on it off and on for a few months, but finally decided to finish it this weekend.  On Saturday, I tweaked some dimensions and laser-cut the final enclosure.  I wasn’t happy with the button holes and text I had on the front of the first iteration, so I got rid of them for the final.  You can adjust the time by slipping a jeweler’s screwdriver or a paper clip through a gap in between the plexiglass sides and pressing the buttons to add hours or minutes. 

I added a small single-pole, double-throw toggle to switch between bright and dim, then soldered the connections before closing it up.  The whole thing is clamped together by a single #10-32 machine screw and a wingnut.  The final result doesn’t look half bad.

2014 RPM Challenge: Accepted!

Today is the first day the 2014 RPM Challenge, which is the National Novel Writing Month of music!  The goal of the RPM challenge is to compose and record an entire album during the month of February! I accepted the challenge by dusting off my Cacophonator and Mohogonator, and got to work making music after dinner today. As today also marks the 50th anniversary of the Beatles invasion, this project drew inspiration from the Beatles’ back catalog!


I used the dynamic duo of Cacophonator and Mohogonator with Auditionator (i.e. Adobe Audition) to record a session for about 12 minutes at a blazing fast 192kHz sample rate.  After chopping the recording into individual tracks, I digitally slowed them down to the customary rate of 44.1kHz, thereby expanding the work to its final ~45 minute length.  For inspiration while I was recording, I listened to Beatles songs sped up to 435% (which is 192/44.1) of their customary speed.  My tracks needed a bit of post-processing: on some of them I chose to bump the pitch back up an octave or two and add “Beatle Fades” to the beginning and end.  Anyway, within twenty minutes after the recording was made, I had edited the songs and uploaded them.  You’ve read that correctly, in less time than it takes to listen to the pieces, they were composed, recorded, processed, mastered, named and uploaded.

Today is also the 50th anniversary of the first Beatles song hitting #1 on the US pop charts: “I Wanna Hold Your Hand.” This whole project was inspired by this apparent coincidence in timing, and each track was directly inspired by listening to the sped-up Beatles original.  I hope you enjoy each of the 11 tracks I created!

While My Cacophonator Gently Weeps
Got To Get You Into My Cacophonator
All You Need Is Cacophony
With A Little Help From My Cacophonator
Sgt. Cacophonator’s Lonely Hearts Club Band
Cacophonator Came In Through The Bathroom Window
Lucy In The Cacophonator With Diamonds
Got To Get Cacophonator Into My Life
A Hard Day’s Cacophonation
You’ve Got To Hide Your Cacophonator Away
Cacophonator Wants to Hold Your Hand

It may be more convenient to listen to the entire album: “Cacophonator 2: Electric Boogaloo; A Love Tragedy in 11 Parts” on the RPM Challenge site’s Cacophonator page. Just scroll down to “My Player.”  There is plenty of February left: I encourage everyone to participate!

Weekend Project — Timed Outlet

I have a cordless drill with rechargeable batteries.  The batteries charge completely in about 20 minutes.  They are not supposed to stay on the charger for longer than that.  However, unless I am standing right there after the charging time, I forget to take the batteries off of the charger.

To fix this problem, I made a timed duplex power outlet out of a countdown timer and a duplex outlet.  I plug the timed outlet into a 120v outlet.  Then, plug the battery charger into the duplex outlet attached to the timer.  Finally, I set the timer to 20 minutes and walk away.  (There are more details about the parts and assembly on the Instructable.)

One problem I had is that the faceplate that came with the timer was too wide.  It covered the timer and a bit of the duplex outlet.  I found a Thing on Thingiverse that uses the Customizer to custom build faceplates that cover from one to five outlets with any configuration.  I used it to make a custom faceplate for two outlets with a single hole for the timer on the left-hand side and holes for a duplex outlet on the right-hand side.  I printed it on the Makerbot 3D printer using black PLA filament.  I used 100% infill to make it solid and durable.

 One problem I had with the print was that the raft stuck to the surface in some spots and would not come off.  So, there are a few rough looking spots.  Another problem is that the hole for the timer knob was a bit too small.  I had to drill it out slightly bigger.

 After attaching the new faceplate, I used my label maker to print the numbers for the dial.

That’s it.  No more ruined batteries due to overcharging.  And, it’s portable!



Home Environmental Sensor Array (Phase 1) Finished

After six months of working on this on-and-off, I installed my home environmental sensor array (HESA) in my basement. Basically, it looks for water in the basement. If it detects water, it shuts off power to my water softener (assuming that the softener is or will, dump more water into the basement), and sends me an email.  The HESA has a Raspberry Pi to detect water and control the PowerSwitch Tail relay.  It also connects to the internet via my home network.


This is phase one of my HESA project. The device I built in this phase will only detect water. Future phases will add the capability to detect more things and be more interactive.

This is basically, my first real Maker project.  I learned or practiced many Maker skills like soldering, basic electronics, and CNC routing. I made my own PCB (that I did not end up using). I did some basic metal work with a jig saw. I learned how to use several software tools for CAD and design. I learned to program in Python. And I had a lot of fun doing it.

Several Makers at the Milwaukee Makerspace helped me with this project. There is no way I could have built this without them. Thanks to anyone who took time to help me move this project forward.

Wiki project page


Raspberry Pi Project Ended

I’ve really struggled with the Raspberry Pi Project. As I posted earlier, the Raspberry Pi kept killing the file system on the SD card. Pete traded me for a different Pi, which behaved much better, making the card last at least long enough to get the operating system and other software installed. Yet the Raspberry Pi continued to corrupt the file system if left running for longer periods. The latest time it totally killed the SD card; I couldn’t even reformat it on my computer.

If I include the Pi in the traveling mascot, I’m convinced it will not survive the inevitable rough treatment. The only other use I can think of for a Raspberry Pi in a travelling mascot is as a home base server for the mascot, publishing the travelogues. Yet it’s too unstable for even that task.

I still like the idea of a traveling mascot that can track it’s own travels, but I’m convinced that building it around a Raspberry Pi is not the proper foundation. I really like the little GPS unit that came in this kit, and will try to build a scaled down version of the traveling mascot with a USB interface to hook up with any computer for collecting data.

Thanks again Adafruit Industries, we really appreciate the kit, and we’ll continue to work with the parts on other projects. Like vultures, some other members have already picked off some pieces of the kit for their projects.

Lighting Control Upgrade!

IMAG3517In an effort to make the lighting control system more user-friendly, the original board-mounted switches have been replaced with a laser-cut zone map! Instead of looking up which zone number corresponds to a particular bank of lights, each location is now identified by a green LED pushbutton.  You can read more about the lighting control system and how it’s been evolving on our wiki: http://wiki.milwaukeemakerspace.org/projects/mmlc