Today, I got to drive home without windshield wipers in a rainstorm.  Fortunately, no crashes and no tickets.

The problem has been a lingering problem and even slowed my drive to work last week because I had to stop and shake the connector to the wiper's pulse board.  After the drive home today, I decided it was time to fix it.  I knew there was content out on the internet and I found this video from Road Rage Customs that basically said to replace the board.  I also knew that there was a resoldering fix.

Lemme think here... drop $21 on a new board or touch it with a soldering iron?

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This is the top of the board. Not much here, just some resistors and capacitors.

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This is the problem.

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BEFORE. This is before I soldered the pin, with the camera lens looking through a loupe. Notice that the solder has pulled away from the pin a little.

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This is the cleaned, resoldered and cleaned (again) pin. Looks way better.

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I also cleaned the grease off these. I'm not sure what they are for.

After re-installing the board, I tested the wipers and they worked except the driver's side wiper was a little loose.  I removed the cover and tightened the bolt holding the wiper arm down and tested again.  Works!

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Category: General Stuff

Backstory:

I'm writing most of this as the ARRL June VHF contest is underway.  With the 706 still laid up (parts did NOT come on Friday the 13th with a full moon... positive omen? No.), it's on the bench gathering a little dust.

So I noticed in QST the August 70cm contest.  I have 20' (+/-) of masts, and 20 watts on 70 cm, and I can make an antenna... but I would need a good directional antenna because I have no interest in buying a 400 MHz linear amp for a contest that I may not have any contacts in.

"Good directional antenna" means a yagi or a quad.  It also means it needs to be rotatable.  I could just turn the entire mast, but I don't know how that will work - my poles are fiberglass, and will have to be guyed, so that may be easier said than done.  I have a junk box full of stepper motors, I have some Arduinos... this could get fun.  Even better, it is temporary, so I don't have to drop big bucks to do this.

So my thinking is that I want an inexpensive home-built rotator.  I want the rotator to know where the antenna is pointing, and there are two components to this - a rotation sensor to tell me where the antenna is pointing and a sensor to act like a compass to tell me where north is.

All that being said, this is post 1 of 2.

Angular Sensors

For the hobbyist, there are basically four encoder options: optical, magnetic, capacitive, and mechanical.  These can be incremental - where it tells you that there is change and how much the change is (or a pulse on change) or absolute (where it gives you a specific position).

Optical

Optical encoders are commonly found in printers and scanners, and the same concept was used by Ben Heckendorn on his Doggie Treat Dispenser.  These have an optical sensor that looks for dark/light marks on a disk on a rotating shaft.  I don't know about prices for these, since I have a few of them from a coworker's printer that stopped working.

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Magnetic

Magnetic encoders operate by using a magnet and a hall effect sensor to sense the change in the magnetic field due to the magnet's rotation.  I'm guessing (operative word!) that these are bad to use in strong magnetic fields (like near a motor, hard drive, or one of those big electromagnets used in junkyards to lift cars).

It appears the only magnetic encoders available (for hobbyists) are analog - they give a voltage output based on the rotational position.  This has the benefit of being absolute or semi-absolute.  Prices range from $10 to $45 from the big US suppliers.  Their use with an Arduino would be similar to the use of a light sensor (although the voltage divider may be built into the sensor, so you may not need to have one separate).

Capacitive

Capacitive encoders work similarly to optical encoders, but instead of using a beam of light, it uses a set of disks and a capacitance sensor.  Benefits (according to CUI) are that dust can mess up optical encoders and that LEDs can burn out.

Capacitive rotary encoders run around $25 and provide up to 2,048 positions of output (that's one every .18 degrees!).  Looking at the linked item, it seems to be the most ready-to-use sensor, depending on the application.

Mechanical

Mechanical rotary encoders are common in selector switches.  They have mechanical rings inside (I couldn't find a good explanation of how this works).  They are inexpensive and common, but I'm not sure of their use within an antenna rotator.  Truthfully, the amount of torque needed to turn a selector switch is so much that I'm not sure this is really an option.

Next Step

As the only picture on this post indicates, I have a motor with a sensor.  I am going to build that into some sort of rotator that can be mounted on top of a fiberglass pole that I can use to turn the antenna.  I don't know if I can have it done by August, but I'm going to try... presuming I get the 706 fixed first!


Category: Arduino

I built an iGate.

I basically used the instructions from KB9MWR, although aprsx was giving me fits.  I have soundmodem running on Debian (it's much easier to get it working there than Ubuntu), and the latest aprsx compiled locally.

Screenshot from 2014-07-01 15:04:42

Hopefully by the time the evening rolls around, more will fill up this map gated by me.

Note that my location on the map is near, but not at, my house (not that I'm not really hard to find, with the magic of ULS/QRZ and Google Street View).

You can see the stats on aprs.fi.  At the time I'm finishing this post, I've only gated 6 stations through and they are only digipeaters and weather stations.  I have seen position packets through, but I don't know if they are not being gated or if they are but APRSIS isn't sending them because they are duplicates.

Either way, coverage on SR 32 (a high traffic highway) and SR 125 (a high traffic roadway) now have some coverage, and it looks like a local nearby digi is down for now (the owner has indicated in a blog post that he's moved, so it may be back sometime).

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Category: Equipment

Despite working at the food booth for the Milford Hamfest, I did get some time to get into the boneyard.  I came back with a few things.

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Astron SS-25M. Yes, the price sticker says "Bad". No power output. It can be fixed - Astron makes some good products, and I'm sure I can find the schematics online.

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Footswitch. Dear reader, you didn't think I'd use the wooden one forever, did you? :-)

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Kenwood TM-201A. Works, but has quirks (some may be by design - like the fact that I have to use an external speaker!). Power output was 6 watts, although I didn't play with the power level switch to see if it would go up to 25 watts. I do like the slide-out bracket it uses.

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Another view of the Kenwood.

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AEP PK-232 Packet TNC.

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Parts. I looked through several bags and picked ones with parts I really want. The meter was partly to round up to $4, although I'm sure I'll use it, too.

Not a bad haul.

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Category: Equipment

I worked a little more on the IC-706 Friday night and located a bad ribbon cable to go along with the bad filter.  I sent an email to Icom in the wee hours of Saturday morning, so I'm sure I'll hear from them on Monday (or they'll hear from me on Monday, one or the other).  Since I'm waiting on parts, I moved that aside for getting into possibly building a packet station.

I started with a box I bought at a hamfest late last year.  The part of the box that I saw first was a TinyTrak3 chip inside.  I saw a Motorola commercial HT second.

So I got into the HT, a Motorola HT90.  It had a few minor challenges, like a short when I connected power to it (which was not with the battery, of course).  Once I fixed that, I installed the two crystals (which one of the prior owners dropped about $75 on in 2002!).  I had to tune it to transmit right on 144.390 (see the image in the gallery with my little test adapter).  Once I did all that, I plugged it into the computer and installed and configured soundmodem.

Aaaaand... nothing.  In fact, looking at aprs.fi, there was nobody in the area that was traveling.  I left it on to (hopefully) get a few receptions on it.

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Category: Equipment

I've written before how I don't understand how I can buy a chip on a board from China for $5, or I can buy the chip alone, in quantity, for $15.

Yesterday, I ordered parts.  I looked at eBay, and ordered over 7,000 parts - resistors, capacitors, LEDs, and transistors (plus two more breadboards).  The purchase was less than $60 and the shipping cost for all of it - from 8 different sellers in China - was $7.59.

I balked at the idea of ordering microcontrollers and chemicals from China (thanks to reading some counterfeit chip blog posts back in 2012), so I ordered 5 PIC16s, some thermal grease, and a few other small items from Newark.  $8.72 to ship these things from South Carolina.

This time, my decision to purchase a ton of SMD parts from eBay wasn't just motiviated by price.  It was also motivated by the fact that out of the three major webstores I look at - Mouser, Newark, and Digi-key, only Digi-key comes close to having an assortment in the price reach of a hobbyist (they have assortments in the $9 and up range, Mouser starts over $100, and Newark starts over $200).  Maybe it has something to do with Digi-key's founder - he is an amateur radio operator.

The difference is that the stuff I ordered from South Carolina, while shipped in two packages (a true WTF? moment there, as 5 chips, 9 battery holders, and a 6.5g tube of thermal grease should fit in a small box, not two) will be here two days after I order it.  The stuff from China is expected to be delivered 6/19 or after, for orders placed in the late morning of 6/3.

Honestly, every month has been busy since January.  I don't expect much time to work on stuff this weekend, and then two weekends will be busy with other things going on, so the timing of the deliveries from China will likely be fine.

One thing of note, I will likely be testing every. single. part.  I wouldn't be doing that if I ordered from Digi-Newark-Mouser, but since the true origin of the parts that I ordered is unknown (except for the 5 PICs, thermal grease, and battery holders), it seems that I'd be better off with an ounce of prevention (of problems).

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Category: General Stuff

As what was on twitter last week, I took a vacation day on Friday and went up to the Hamvention.  I didn't buy much, just a small kit and a rockbound 6m FM rig. The radio was $5 (it makes it feel so much better to mention the price when talking about the fact that it is rockbound).

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The first thing I looked into was the 6m rig.  I plugged it into the power supply and a dummy load with a watt meter and hit the TX... nothing.  I even tried yelling and whistling into the microphone (which didn't - and shouldn't have - made a difference).

I took a look inside.  I figure there is at least $5 worth of parts in here, so it isn't a loss.  Or I could try to fix it, but I'm not sure that would be worth my time.

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The better part of Hamvention was meeting several twitter friends in person and catching up with a few local (and non-local) friends that I don't see often.  That definitely made it a good trip!

BnxV9llIAAAncD3

H/T to K0KDS for the pic!

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Category: General Stuff

Tweetup: Meet your fellow "tweeps" at Hamvention.  11:00 AM both Friday and Saturday (and Sunday, if anyone wants to meet) at the Hara Arena Loading Dock.  This is the same location used for the past two years.  Meet near the drayage building to be in the shade (presuming it isn't raining).

Rain Plans: There is a 40% chance of rain on Friday, and a 30% chance of rain on Saturday.  Should it be really raining (not drizzling), we'll meet in section 30 of the main arena, although that may move.

Frequencies: There will be a talk-in frequency circulating via Twitter via DM.  It'll be somewhere on 70cm.

HamventionTweetup_reallysmall

Click for a larger and more expanded picture.

Direct link to large map (right-click to save, sorry it isn't a PDF).

-73- and see you there!


Category: QSTs

I decided a few weeks ago to bring some life into my office with a plant.  Since I was getting a few things at the local 24-hour megalowmart, I decided what the heck.  One plant, bag of dirt, and pot (that was on sale), I had this...

 

It's called a "Little Herman Ivy"

It's called a "Little Herman Ivy"

I decided I wanted something to help me keep this thing alive.  I didn't want to go the route of a twitter reminder, as I'm in here nearly every day.  A nice, visual indicator should do well.

Since I'm a traffic engineer, I thought something with a traffic signal would be appropriate.  A green for "you're good", a yellow for "getting dry", and a red for "too dry".  I also like the idea of using a PIC since I haven't used those very much and I wanted to expand my horizons.

After some breadboard experiments on a breadboard, I even designed my first PC board.

This is the PC Board from OSHPark.

This is the PC Board from OSHPark.

The circuit uses two coin cells, a PIC 16, and a few other components (click for schematic).  There is one issue with the boards - there is silkscreen covering the copper that is supposed to sense the moisture in the soil.  I'll have to fix that with a razor.

Stay tuned to see how it does, once I solder components and build.  I'll post the source then.

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Category: PIC
Tags: ,

Last week (on a post that proved that even an evil genius can sometimes mess up simple math and set a post to fire 4 days early) was the introduction, today is some new findings.

Memory

If you follow the directions and treat this like an "Arduino Pro or Pro Mini (3.3 v, 8 MHz) w/ATMega 328", the Arduino compiler will tell you that there is a 30,780 byte maximum.  In my experience, the maximum is around 26,000 bytes.  Wyolum knew about this, and this is why they included a micro-SD card slot and card.  At one point, I tried creating a program that would tell the temperature and lines from the Zero Wing intro ("All Your Base Are Belong To Us!").  It didn't go well.

Temperature Sensing

The temperature sensor is very simple to use.  Recall in the last post, the sensor itself is populated, but a 0.1 uF capacitor (C8) is not.  The sensor might work without the capacitor, but it likely works better with it (at least I hope so, I populated the cap without testing and I have zero interest in removing it).

To read the analog pin and get it to a voltage, the following code works for me:

int ar=analogRead(7);
float vref=3.3;
float temp=ar*vref/1024.0;

Even though the Pro and Mini do not have 7 analog pins, the Arduino IDE and compiler not only do not complain about not having the pin, they compile it correctly without modifying any of the libraries (Good on ya, Arduino!).

Looking at the data sheet, there is a simple equation for the temperature:

V_{out}=T_{C}*T_{A}+V_{0}

Where:

V_{out} is the output voltage

T_{C} is the temperature coefficient

T_{A} is the Ambient Temperature

V_{0} is the voltage at 0°C

Per the documentation, I used V_{0}=0.5v and T_{C}=0.01V/C.  Using algebra (who says you'll never need it?), I used:

T_{A}=\frac{V_{out}-V_{0}}{T_{C}}

Which would give me the temperature in Centigrade, and after that,

T_{F}=\frac{9*T_{C}}{5}+32

In Arduino, that wen't like this:

temp=temp-0.5;
temp=temp/0.01;
// C to F
temp=(9*temp)/5+32;

And it seemed to work correctly.  I was getting temperature readings of around 74 in my office, and it seems like that is correct.  The final code is below.

...and of course, I can't show all this code without the finished product:

It's a warm 75 in here today... and it does feel kinda warm in my office.

It's a warm 75 in here today... and it does feel kinda warm in my office.

By the time this post fires, I will have just returned from a transportation conference.  I hoped initially that I'd have more with this post, but it'll have to wait for next week's post.

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Category: Arduino

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