Azega

555 Time Lapse Intervalometer

admin — Tue, 01 Mar 2011 22:45:32 +0000

This is my entry for the 555 Contest recently started by Jeri Ellsworth and Chris Gammell. It is a camera timer (aka. intervalometer) for taking time lapse videos with my DSLR. It is a very simple circuit designed around a 555 timer IC. It has indicator LEDs, a relay to control the camera, and a potentiometer which allows me to set the photo interval between 15 seconds down to around 1 second.

I’ll admit that it’s not much to look at, but that is because I threw it together in a couple of hours from parts I had laying on my workbench. I designed, built, troubleshot, and did a test run in one short evening. I have wanted to experiment with time lapse photography for a while now, and this seemed like a good opportunity to give it a go. I’ve got some other projects related to time lapse and general photography in the works, so click the subscribe button so you can be notified when they’re available.

Design:

At it’s core, it’s just a basic astable oscillator. The output is connected to a relay which closes the contacts to the camera remote. I used a relay to isolate the camera electronics from the circuit and so I wouldn’t have to worry about what voltages were required by the camera. I also added a snubber diode to the coil side of the relay to arrest the voltage spike when the relay turns off.

And Here is basically how it was laid out on the breadboard.

Connections:

I hacked an old cell phone remote for the connector to plug into my camera. For power, I used an old 7.5 volt wall wart.

Testing:

Here is the initial test showing the oscillations. This is before I had it hooked up to the relay and camera.

Trial Run:

Here is the first complete trial. I set it to take a picture every 5 seconds, then used Sony Vegas HD to compile them into a 15 fps video.

I was originally going to build this circuit using an arduino, but I wanted to do something for the 555 contest, so I thought this would be a good application. I like this circuit so much and the parts are so cheap, I’m going to rework it to add a few features and build it more permanently on a circuit board and put it in a case, so check back for that.

Let me know what you think in the comments section below.

Update:

(everything below this point was added after the close of the contest)

I created a more permanent version by soldering it onto a protoboard that fits inside an altoids tin and also changed the power source to a 9v battery to make it more portable. Other changes include changing the size of the capacitor to 470 uf adding a 470 ohm resistor in series with the potentiometer to set the minimum interval to about 1 second. Previously, if you turned the pot all the way down, it would just stop oscillating and it made it hard to set times shorter than a couple of seconds. Now, the range is from about 1 second to around 30 seconds.

What I want to do now is to measure the current being drawn by the relay and see if I can adjust the current limiting resistor so the battery lasts longer. I also want to look into using an opto-isolator or a solid state relay to eliminate the relay and lower the overall power consumption.

Here is a test of the new design and a better video.

Here are some tips for capturing time lapse video:

Set your camera to manual mode. Manual mode will let you lock down the exposure, aperture, ISO, white balance, etc. You don’t want your camera to reevaluate the scene in the middle of the video and give you an inconsistent look. I usually take a few shots in aperture priority mode to figure out what the best settings will be.

Set the focus manually. If you leave it in auto focus mode, it will try to refocus on the scene every time it takes a shot. This will make it use up your battery faster, take longer to take shots, and the focus will keep changing in your final video.

Take more frames for smoother video. Both videos above were captured at about one frame every 5 seconds. The difference is that the first video was rendered at 15 fps and the second one was rendered at 30 fps and I think it is more smooth.

Arduino Servo Motor (Part 1)

admin — Wed, 23 Feb 2011 06:34:32 +0000

Controlling a servo motor with an Arduino or other type of microcontroller is probably the easiest way to get started in robotics, motion art, or any other reason you may have to make your electronic project interact with the real world. Servos are very simple to interact with and in this post I’ll show you how to connect one to an Arduino.

Servo motors are a specific type of motor, often used in hobby RC cars and planes, that rotate to a specific angle when a corresponding signal is applied to the pulse pin. Servo motors are very easy to program and very strong for their size. This makes them useful for a wide array of applications. The internal components of a servo motor consist of a regular DC motor, which does the actual work, a system of gears to increase the torque to the output shaft, and a circuit board and sensors to control the movement of the motor.

Wiring:

To get started controlling a servo with your Arduino, you only need to connect three pins. There are two pins for power and ground. For a small servo or just for testing, you can connect these directly to the Arduino. If you are controlling a large servo motor, you might want to use an external power source. Just remember to connect the ground from the external source to the ground of the Arduino.

The third pin is the pulse, or signal pin. This accepts the signal from your controller that tells it what angle to turn to. The control signal is fairly simple compared to that of a stepper motor. It is just a pulse of varying lengths. The length of the pulse corresponds to the angle the motor turns to. Typically a pulse of 1.25 milliseconds causes the motor to rotate to 0 degrees and a pulse of 1.75 milliseconds turns it 180 degrees. Any length of pulse in between will rotate the servo shaft to its corresponding angle. Some servos will turn more or less than 180 degrees, so you may need to experiment.

Programming:

The Arduino software comes with a sample servo sketch and servo library that will get you up and running quickly. Simply load it from the menu as shown below. Their example uses pin 9 for the pulse wire, so to keep it simple, that’s what I used. You could use any of the data pins and, if you add more than one servo, you will need to. The Sweep sample simply rotates the servo back and forth from 0 degrees to 180. There is another sample sketch that uses a potentiometer as an input to control the angle of the motor, but I’ll get in to that later.

The code is pretty basic and well documented. It first loads the library needed and sets up which pin to use as the output.

This line tells it to move from 0 degrees to 180 degrees one degree at a time:

for(pos = 0; pos < 180; pos += 1)

And this line tells it to move back to 0 degrees one degree at a time.

for(pos = 180; pos>=1; pos-=1)

You can play around with those lines to get different effects. That is what I’ve done in the video below.

If you’ve found this tutorial helpful or if you’ve done a cool project using an Arduino and servo motors, let me know in the comments below.

How to Child Proof a Treadmill

admin — Thu, 28 Oct 2010 03:17:03 +0000

Many treadmills have a way of folding up to save space, but often, as is the case with mine, the latch is very simple and not enough to keep little hands from unlatching it. The base is also very heavy, so if it were to fall on anyone, it could cause serious injury. This is how I child proofed my treadmill using a padlock and a few parts from the hardware store.

This was my temporary solution. I just tied it up in place, but I wanted to start using it again, so I needed something a little better.

Below is the original latch. It’s just a pin held in place by a pretty weak spring.

Parts Needed:

5 feet of 1/8th inch coated wire cable. $2.25 (I got the plastic coated cable so it wouldn’t scratch anything or anyone)

2x wire rope clips $0.96

2x wire rope thimbles $0.96

2x 1/4 inch by 4 inch eye bolts $1.04

2x lock washers $0.22

2x hex nuts $0.10

1 padlock (not shown) which I already had on hand

Steps:

Step 1:

The first thing to do is to slip one of the rope saddles (or thimbles) through one of the eye bolts. (only need to do this to one side)

Then run the wire rope around the thimble and secure it with one of the clips. Just work back and fourth on the two nuts to get it as tight as you can. I also threaded the nuts

Step 2:

After securing the first side, measure the length of cable needed to reach the other side. Then wrap it around the other thimble and mark where to cut the cable, leaving about an inch past the end of the thimble so there is room to attach the clip.

Cut the cable on the second mark. This is difficult because wire rope is designed to be hard to cut. I used some pliers with wire cutters and just worked the cable, turning it and cutting it and it wasn’t too hard.

Step 3:

Attach the second thimble and clip as in step 1. Here is the completed cable.

Step 4:

Now to drill holes in the upright legs of the treadmill. Use a bit the same size as the eye bold so it just barely fits through.

Step 5:

Attach the eye bolts with the lock washers. One on each side.

Last Step:

Attach the lock to the open side.

And that’s all there is to it. For under $6, I feel much better about the safety of this latch.

Leave a comment below to tell me what you think or if you’ve tried a similar approach.

Disclaimer:

Don’t make this. I accept no responsibility if you do.

DIY HDTV TV Antenna (Bowtie)

admin — Sun, 17 Oct 2010 21:50:45 +0000

Build your own HDTV TV Antenna to cut the cord from your cable provider and save $1000 a year. This DIY antenna is very easy to build with just a few basic tools and a few supplies available from the hardware store.

After being disappointed with the current channel offerings and ever increasing price of our local cable provider, we recently decided to disconnect our cable TV service and go for over the air broadcasts as well as the many online services available now. I built this DB4 antenna, also called a bowtie antenna, to increase the rang of signals I could pick up over the basic rabbit ears antenna.

This is the first of two antenna designs I’ve built. Subscribe or come back soon to see the second version of the DIY HDTV TV antenna.

Parts Needed:

13 feet of 12 gauge Electrical wire

10x Wood Screws (I actually used 6 x 1/2” metal screws)

10x #10 Washers

Matching transformer (balun)

1×3 or similar size board around 22 inches long

Start by cutting the 1×3 to length and marking the spots for the holes. Make the first set about 2 inches from the top and then measure 5 1/4 inches to the next set and and continue down making each set of holes 5 1/4 inches apart. The holes for each set will be centered on the board and 1 inch apart.

Drill out the spots you marked for the screws with a 1/16 drill bit. This may be unnecessary, but I like to do it to keep the wood from splitting.

Cut 8 pieces of wire about 15 inches long. They only need to be 7 inches after folding in half, but I like to add a little extra and cut them to length later. I bought electrical wire off the spool by the foot. You can also get romex type 12-2 or 12-3 house wire with three or four wires in a sheath (hot, neutral, ground). Romex is a couple cents cheaper per foot, but requires more work to split the sheath and separate the wires.

I couldn’t find any bare wire, so I needed to strip the insulation off the areas where the connections needed to be made. I used a wire stripper to score both ends of the area to be stripped then used a utility knife to split the insulation and peel it off.

Bend the wires into “V” shapes then cut two more pieces of wire about 17 inches long to connect the bowties. Strip the ends and three spots on those wires to make contact with the center nodes and the center tap. (only the two nodes are shown stripped in the picture below)

Next put everything together with the screws and washers. Make sure everything is snug and all the bare areas of wire are touching. Measure from the screw to the tips of each “V” and cut them off at 7 inches. Then spread the tips apart 3 inches.

This is the only kind of balun (matching transformer) I could find at the hardware store when I was getting the other supplies. It isn’t exactly what I was looking for, but it will work with a little modification. This matches the high impedance of the antenna to the lower impedance of the receiver.

This is what it looks like on the inside.

I cut a hole in the side of the balun then cut the end off a piece of coax cable I had and soldered it to the contacts of the coax connection.

So it looks like this.

I cut, stripped, and bent two short pieces of wire to attach the balun to the back of the antenna.

I screwed the connections for the balun to the front and wrapped the wires around to the back so I could attach it to the back.

Here I screwed the cover for the balun to the back of the antenna to hold it in place, then attached it and secured the wires with the pigtail hanging down.

And here’s the end product. I used some scrap wood to build a base for it. What you do here would depend on where you plan on mounting it. I just wanted to set it on a shelf for testing, so a simple base worked for me. I will eventually mount it permanently in the attic for better reception.

Results:

Here are the results I achieved after switching from a normal set of rabbit ears to the bowtie antenna.

I’m using an HDHomeRun connected to my windows media center as the TV tuner. Below is the software that came with it showing the signal strength.

As you can see, the signal strength went down, but the signal quality went up, which I think is the more important number.

Update:

While, the reception was better, it wasn’t what I was expecting, especially since I live just a few miles away from several TV stations. I finally found a different kind of balun (matching transformer) at Radio Shack and decided to give it a try.

Results Round #2:

As you can see here, switching to the better balun made a significant improvement. The signal strength is still lower than the original rabbit ears antenna, but the signal quality is noticeably higher.

Update #2:

I’m still not happy with the results, and after doing some research, I think the issue is signal reflection. Basically, since I’m so close to the source and the signal is so strong, I’m getting reflections of the same signal from different directions at slightly different times. These out of sync signals are interfering with each other and causing the signal to drop out often.

To solve this all I need to do is to add a reflector to block the signals coming from behind the antenna. I didn’t discover this until after I had built a different design. To see my new design based on the Gray-Hoverman Antenna and the reflector I added to it, stay tuned to this blog by subscribing to the RSS feed or the email newsletter at the top of this page and you will be informed as soon as I have posted it.

Let me know if you have tried this design and what your results were in the comments below.

Fix a Cassette Tape Adapter

admin — Thu, 07 Oct 2010 21:05:40 +0000

Have you ever had a cassette tape adapter that quit working all of a sudden and just keeps getting ejected from your tape deck? Here is an easy and virtually free way to fix your cassette tape adapter and get you back to listening to your iPod, iPhone, or whatever mp3 player you use it for.

I used to have a nice hack in my Explorer where I patched an auxiliary port inline with the build in CD changer to connect my iPod MP3 player. All it required was that you have at least one CD in the changer to trick it into playing, and the aux port hijacked the audio line to inject its own signal.

Eventually, my CD changer died so this hack stopped working and I was looking for another solution. I had no idea what was wrong with my CD changer which needs to send a signal to the radio saying that it’s playing something. My radio has a tape deck that I never used, so I decided to get a cassette tape adapter. This technology has been around for probably 30 years, but since the increase in popularity in iPods, it seems like old technology like this and FM transmitters suddenly doubled and tripled in price.

I ran across a cheap tape adapter on clearance so I thought it would work until I figured out a better way to listen to my iPod (now an iPhone). Now, a year or two later, I’m having problems with my cassette adapter. It seems to happen more when it’s cold, but I think it’s locking up and my tape player will think it’s at the end of the tape and spit it out. When it does that sometimes I can just stick it back in and it starts working again, sometimes I beat it on the dash and it works again for a while, but it takes 30 seconds or so to get it working again, then I have to rewind my podcast or audiobook that I’m listening to, and all this is dangerous to do while driving.

I never want to spend money if I don’t have to, and I’m a curious person anyway, so I took it apart to see if there was something I could do to fix it.

Inside was just a few plastic gears.

It is a pretty simple mechanism that tricks the cassette player into thinking there is an endless tape playing. The plastic gears look like they’re in pretty good shape, but there is no sort of lubrication and it’s just plastic rubbing on plastic.

Lifting up the gears you can see plastic dust where the gears have word down a little.

After cleaning this dust off I added some 3 in one oil. You could use any kind of machine oil.

First, I tried dripping some on, but it was too hard to control and I didn’t want a bunch of excess oil dripping down into my tape deck. (although it probably wouldn’t hurt it) Then I soaked some oil into a paper towel and rubbed it on the gears and all the areas where the plastic parts rub together.

After everything was well coated, I put it back together. This is where it helps to have a picture or some other method of remembering where all the gears went.

After putting it all back together, it’s back in my Explorer and working like new. I think it’s even a little more quiet than it was. This free fix just took a few minutes and saved me the expense and time of looking for a new converter.

Let me know in the comments below if you tried this or another fix and how it worked for you.

How to Read a Resistor Color Code

admin — Mon, 20 Sep 2010 18:16:54 +0000

Here is a nice resistor color (colour for some of you) code diagram I ran across online. I used to read resistors so often that I didn’t need a guide, but It has been so long that I can no longer decode them from memory. Lately I’ve needed to read some resistor color codes occasionally so I found this chart online. I thought it was very easy to read and have it hanging on the wall in my lab for quick reference. I don’t remember where I found it and I’ve seen it in several locations so I don’t know who to credit but I wanted to repost it here for everyone to make use of.

Here are some tips that might speed up decoding resistors.

Most of the resistors you come across will be the 4 band variety like the example on top and most of those have a tolerance of 5%, so the last band is usually gold. You will also see the same numbers over and over again like 10, 22, and 47, … so you will get to know those color combinations and quickly recognize them. Then it’s just a matter of figuring out the multiplier so you know if it’s 47 ohm (black), 470 ohm(brown), 4.7k (red), 47k (orange), etc…

Warning: Made in USA (Photo)

Brakk — Mon, 23 Aug 2010 21:16:24 +0000

We were at the park the other day and I noticed how only a few of the words stood out on the swings creating an interesting phrase.

555 Time Lapse Intervalometer

Fix an LCD Monitor

Brakk — Thu, 22 Oct 2009 22:37:43 +0000

This is a story of how I was able to fix a broken and long forgotten LCD monitor. This is a cheap CTX monitor, but I’ve seen this method work on other brands of monitors and I think it is a pretty common problem.

These monitors cost around $200 new, which was a pretty good price at the time. I think the original warranty covered them for a year or two. What ever it was, it failed shortly after the warranty expired, which is typical for many electronics.

I’ve seen several of them fail in the same way, first it starts blinking on and off for a few seconds until it warms up, then works fine. After a few days it starts taking a few minutes to “warm up”, then finally it never stays on and just blinks on and off forever.

After replacing it and forgetting about it on a shelf for months (years?) I wondered how hard it would be to get it working. I did a little googling and found a site where someone said the capacitors in the power circuit often fail and simply replacing them cured the problem. Capacitors are cheap, so I thought, “why not?” and gave it a go.

This monitor wasn’t hard to break in to. First, remove the screws holding on the foot and the back and pop the side clips apart with a screwdriver.

Then there are four screws holding on a cover over the circuit board.

Then you can see the circuit boards. The board on the left is the power board that takes in AC line level voltage and converts it to various voltages to supply the logic board and the back lights. On the right is the logic board that takes the signal from the computer and controls the LCD.

Here is a closeup of the section of the power board with the capacitors that will be replaced. It’s hard to tell from this picture, or even in real life, but a couple of them are bulged a little. This is normally a sign of a bad capacitor when the top bulges and sometimes splits. Usually it’s very obvious, but it was very hard to tell with these, so I wasn’t even sure if this would fix my problem, but I tried anyway.

Here are the six capacitors I removed. To find replacements, just look on the sides for the voltage (v) and capacitance (uf) rating, then search for replacements on mouser.com or some other electronic component site.

If you look close you can see these two capacitors are bulged a little. I probably could have gotten away with just replacing these two, but like I said, capacitors are cheap and replacing them all at once is easier than replacing one, put everything back together, test it, take it back apart, replace another one…

Here is a new capacitor next to the two that are bad. Can you tell the difference?

And like magic, after soldering in the new capacitors, and screwing it all back together, I have a monitor that works like new!

Have you repaired a monitor using this method or any other method? Let me know below!

Good luck and happy soldering.