R/C P-38 and another crash

I fixed her up and took her for a spin.
It was relatively calm, just a little gusting.

Well, by the time I got started, the wind picked up.  I should have aborted, but I am stubborn.

As soon as I got it in the air, I lost control.

I thought I managed to get it back, and tried to enter a left-hand pattern.

Suddenly, a huge gust kicked up, and she went down. Hard.

Overview

Both tail booms took serious damage.

The battery popped out, I had to hunt for it.

Left aileron is almost disconnected

Left and right props are wonky.  I don't know if I can fix them. Or by a new set... Or

R/C P-38 and hard landings

so a friend is trying desperately to get me into R/C airplanes. So he surprised me with a Flyzone P-38. It is a micro plane, 4oz tops.

Well I am not a particularly good pilot. Two flights, two crashes.

First flight ended in a nose dive. Broke the nose right off. Fortunately, the nose protected the props. The fix was pretty easy. Good as new.

Second flight. Much better. I even controlled it in heavy winds. Unfortunately, I can't tell whether it is coming or going, and I flew it imto an oak tree. I ripped the tail off trying to get it down.

I am gluing it back now. Maybe a 3rd flight this week. 3rd time's the charm, right?

Turtle Hat

I learned to knit when I was deathly ill on New Year's.

After the perfunctory "hello world" of knitting, a scarf, I tried to do something a little more interesting.

I came across some "hairy" yarn in a mossy green color. I decided to make a "turtle shell" hat.

This was my first real project. I didn't have a pattern; so I made it up on the fly. The first attempt was HUGE. Yeah, round 2.

I shrunk it and did a 2x2 rib. I used 2 continuous strings (green and brown). When I was done, it was gorgeous. Super cute, perfect, and.... SMALL.

It was so tightly knit from carrying the 2 lines the whole time. I gave it to a friend for her doll.

I was so frustrated, that I promised to never do it again. Instead I did a simple grey hat, fast, easy and pretty.

Then I got the itch to try the turtle hat again. This time I ran 12 lines! One for each color and patch. It was a difficult task to keep everything straight, but it worked. This time it was JUST RIGHT.

I gave it to my niece(nicknamed "Princess Turtle"). I would like to thank her for being my model.

Spy Trakr: Headphone Jack

The first hack everyone does to the Spy Trakr is to install a headphone jack. I jumped on the band wagon. My biggest issue was the mic-speaker feedback when I had the Spy Trakr next to the remote; LOUD!

So I opted for headphone jack AND a volume knob.

I carved out a slot in the right grip with a soldering iron (it is a sin, I know) for the jack (ebay 5-pin) and a small wheel potentiometer (Radio Shack 271-001). This 5-pin jacks automatically switch from speaker to headphone when you plug it in.

This is a crude wiring diagram. It is sad how long it took me to figure it out.

This is a shot of the holes and where the stuff fits in the remote.

The components assembled and awaiting final gluing.

The final installed setup.

The speaker shuts off when the headphones are installed.

Speaker: the wheel controls the speaker from NORMAL to mute. Not a lot of fine control.

Headphones: the wheel controls the headphones from REALLY LOUD to NORMAL.

Overall, I am happy with the results.

Spy Trakr: Motors

There are many complaints about the Spy Trakr motor; all of them say it's too weak.

I opened it up to see what we were dealing with.

Four gears in the train from the motor to the wheel

10:28

10:38

10:38

overall 1:40.4

Should be beefy enough, but the motor spins so slowly; the wheel does about 100 RPM.

Three wires to the motor: black, red, orange (the other wheel is green, blue, yellow)

This is a simple brushed DC motor. Orange/black power the motor and red is a ground to motor chassis.

The motor itself is a little larger than the typical guys I see at the hobby shop.

I will revisit this later to get a better idea of the motor, and how to improve the situation.

Spy Trakr: Wide Angle Lens (more)

A little bit more about the lenses and installation.

This is the 1.8mm lens installed on the board.

I had to make a custom lens holder and I made it a little loose. The lens would shift when I installed it in the TRAKR. So I manually focused it and dribbled Elmers glue into the threads overnight. Now it is sturdy enough to install in the 'bot.

These are 3 of the 4lenses I used (excluding the one I installed).

The TRAKR lens is on the right. It has a 9mmx0.5 thread on the lens. This diameter is less common, but not too bad. The screw holes on the lens mount (and the TRAKR CMOS) are 18mm apart. This lens has an IR filter built in. This lets 850nm pass and blocks the other IR frequencies.

The other two lens are from the Surveyor SRV-1 (basic on left, wide angle in the middle). These are both 12mmx0.5 thread lenses. Much more common size. The included lens mount is on the center lens. The screw holes on the lens mount are 22mm too big for the TRAKR.

So I built my own lens holder: 12mmx0.5 thread with a narrow 18mm base. Not hard, but I was sloppy (thus the glue)

Spy Trakr: Wide Angle Lens

I recently purchased a Spy Gear Spy Trakr. $80 R/C Tank with video camera that displays on the remote. It's claim to fame is that it runs Linux and is user programmable. Hackaday.com did a few good write-ups on it //hackaday.com/2010/08/27/spy-video-trakr-first-impressions/

Unfortunately, Spy Gear has stopped supporting it and taking the source code with it. Darn.

In the meantime, it is still a fun little toy. I drove it around the apartment, tough to navigate on the small screen. Just for giggles, I thought I would swap out the lens with a wide angle lens. I had 3 other lenses from work: 3.6mm, 2.2mm, and 1.8mm. (The Spy Trakr lens looks to be 3.6mm).

These lenses are 12mmx0.5 thread, very common; the Spy Trakr lens is 9mmx0.5 thread, less common.

This is an image with the default lens

This is an image with the 1.8mm lens

A top view of the kitchen, er... test arena.

The green line is 1.8mm and red is the 3.6mm.

The wider view and increased "peripheral vision" make the Spy Trakr an order of magnitude easier to drive.

A couple of notes about the 1.8 mm lens. It was labeled as 180-degree field of view. Clearly not 180 degrees. The fine print is that on a 1/3" imager it yields a full 180-degrees, but on the Spy Trakr 1/4" imager, we get 90-degrees. Again, still better than the 45-degree Spy Trakr lens.

A problem though, the wider lens needs A LOT more light. Thus my images are bad outside of natural sunlight. D'oh. External LEDs will fix that.

68HC11 Bootstrap mode

In 1999, I received a Super T-Comp; a 68HC11 based microcontroller board that is similar to the Handyboard.

While working with it I released the sacred smoke. I blew out 3 chips.

I repaired the damage, but I couldn't get it to work right again. So it sat in my toybox waiting for me to try again.

In 2010, I am taking a class in embedded systems; so it is time to try again.

Inspecting the board again, I found a bad chip that I missed; a NAND gate driving the external RAM. I will fix that this week.

Regardless I should be able to talk to T-Comp in Bootstrap mode. PCBug11 is the original tool for talking to 68HC11. It doesn't run on modern (fast) computers.

So I tried TeraTerm terminal software. Finally did established communication this morning.

68HC11 has 4 modes:

Single Chip: no external RAM

Expanded: external RAM

Bootstrap: single chip, using bootstrap loader in ROM

Test: Uh? don't know

Bootstrap Mode

Hold ModA and ModB low

Toggle Reset

Release ModA and ModB

within a second

send a byte over SCI (serial port) at 1200 Baud, No parity, 8 bits, 1 stop bit.

It is now ready to accept a 256 byte program. 68HC11 will echo bytes. Once it recieves 256 bytes, the program counter resets to $0000 and starts to run the loaded program. In theory.

Hacking the PSP

Everyone has hacked the PSP to put non-Sony firmware on.

You can still run your games, AND install homebrew stuff.

This was the original goal when I bought my PSP. I got distracted by actually playing games.

I finally got around to doing it.

I have the GOW edition PSP slim, it had Sony firmware V3.94 installed.

I sort of followed the instructions that I found here

http://forums.pspslimhacks.com/tutorials/5-guide-psp-custom-firmware-reference-guide-minor-update.html

Things you need:

Pandora Battery - modified battery to allow access to the PSP bootstrap mode,

I borrowed one

Sony memory stick - 1Gb stick works fine

PSP Grader v0.008 - installs firmware, I got it here

http://pspslimhacks.com/psp-grader-v008/

modified PSP firmware - overwrites the Sony firmware, I got it here

http://www.psp-hacks.com/file/1568

Connect the PSP to your PC; start USB mode.

Copy the Sony memory stick to PC

Format the Sony memory stick

Start PSP Grader

Locate the eboot.pbp in the PSP_500_FW.zip

Download file to stick

Disconnect and power off the PSP

Remove battery

Insert memory stick (if you haven't)

Hold down the L button

Insert the Pandora Battery (often PSP auto-starts) and start PSP

Back up NAND

Restart PSP

Install 5.00 M33 (or similar)

Done.

I have spent all my time playing a Magic the Gathering Homebrew (Wagic) in stead of programming anything.

Shelves Part V - Vini Vidi Vici!

Actually, I finished the shelves by the end of the last post, but the completed shelves deserve a private showing.

TaDa!

Amazing! Beautiful!

And with stuff...

less beautiful, but nothing is overflowing.

Shelves Part IIII - Install!

Problem with the shelves is that they won't fit in the pantry with the shelves intact. As designed, the shelves are attached to the back board from the rear. Thus I can't screw the individual shelves back in place given the tiny space behind the back boards in the pantry.

Instead I decided to add supports to the back boards, under the shelves. The supports will be screwed in from the rear. Then after the unit is installed I can add the individual shelves from the front.

Out of concern that the full shelves were too heavy to attach solely to the wall, I added support legs.

Sunday morning I ran out to my local hardware store.

I picked up 12 feet of 1" x 2" board.

I cut out 12 boards, rounded the edges and stained them.

Then I went on vacation.

First the legs:

Then mount the back boards to the wall and the legs:

Then add each shelf, screwing the supports from the bottom:

Shelves Part III - Aw Crud

Time to install.

I emptied the pantry and started removing shelves.

The contents are scattered about the kitchen.

So I started the installation process.

I ran into a small problem. It won't fit in the door.

Initially, I planned to install the backboards, then the shelves.

Installation would have been easy as pie.

But somewhere along the line, I changed my mind, and assembled it first.

Oops. I can't get it inside the closet. No matter how much twisting, shaking, lifting, grunting I do, one corner sticks out. Oh Crud.

I have a plan to fix it. I can install supports under the shelves. Wish me luck.

Shelves Part II - Stained

I hesitated about staining the shelves. Somebody pointed out, "it's in a closet, go for it".

I chose a dark red (Minwax Red Oak 215).

I worried about the stain on the edges of the plywood.

There were a few spots where the dado cuts chipped the plywood, so I looked into wood filler.

I tried the Minwax Stainable Wood Filler. It looks/feels like beach sand. Odd.

Seemed to blend okay.

Test everything on scrap first!

The stain was much darker than I expected (brown, not red)

It did not look good on the edges of the plywood.

But it looked worse on the edges with the wood filler. (I think)

Well, I used the wood filler on the deep gouges, but not on the edges.

I sanded everything with 220 grit sandpaper and an orbital sander. Fairly quick job.

I applied 2 coats of 215 (2x 8oz cans, no left overs). 6 hours after each coat.

FYI the stainable wood filler doesn't stain. (the yellow stripe just above the shelves)

Applied a coat of Minwax Fast Drying Polyurethane (32 oz can, used less than a 1/4) to all of the stained surfaces.

After 6 hours, I felt the surface. Very rough.

So I lightly sanded (220 grit) the top of the shelves.

Applied another coat (again just to the top of the shelves)

24 hour cure. Very nice!

Most important thing I learned: I need more light.

I found a few spots where I missed stain or clear coat.

Next I need to figure out how to mount it.

One last thing. Remember to clean the stickers off with rubbing alcohol first.

Woodworking Project

I took a woodworking class at the community college. But what to do for a project?

Someone pointed out the hell that is the pantry.

I have a project now.

The pantry is in a tight corner. The current shelving is 8"x2' wire mesh. It uses less than 1/3 of the space in the pantry.

My proposed shelves are basically 2'x2' triangles (with additional 4" of overhang). This should provide a lot more space.

I should have documented the individual pieces before assembling them. Oops.

Stats:

• 3/4" plywood backing (1/4" deep dado cuts for the shelves)
• four 1/2" plywood shelves
• two 3/4" plywood shelves ( from the leftover from the backing)
• 11.5" between the shelves
• top shelf is cut much deeper (not triangular) so I can reach stuff on the top.

After assembling the shelves, I decided to round the edges (better late than never) .

I bought a router and bits (cool toy!).

I used a 3/8" round-over. The bit is recessed to 1/8" cutting surface.

I like the final look.

The next step is stain and protect.

Motor Lockout and Timer

I need a remote box to control the RPM of a 20 HP rotor.

Since, the AC Drive provides 90% of the work, the remote box is a pretty easy task.

It has 4 parts:

10-turn rotary potentiometer - vary rotor speed from 0-12000RPM,

Kill switch - big red button that cuts power to the motor if something goes wrong

Something ALWAYS goes wrong

Enable switch - small button that lets command from the AC Drive go to the motor

Lock out - timer that makes sure the command from the AC Drive is zero before letting you use the Enable switch

The diagram is shown below:

The red lines S1, Sc:

If S1 is connected to Sc, then the Drive commands reach the motor.

Ultimately, the circuit will connect S1 to Sc if Enable switch is hit.

Av, A1, Ac:

10-turn pot to control RPM.

This is a basic voltage divider; the Drive senses the reference voltage (Av) compared to A1.

Enable Switch and Panic Button:

The yellow block is a 3PDT 5V relay.

When the coil is energized by pressing the Enable button:

Pole 1 connects the main coil to 5V. Thus the coil stays energized after the Enable button is released.

Pole 2 connects S1 to Sc.

Pole 3 energizes the Green LED.

When the Panic button (normally closed) is pressed, it breaks the circuit and opens the coil.

Once the circuit is enabled, the Panic button is the only way to kill it.

The key is that NOTHING happens if the lockout transistor (NPN) is not energized by the output of the Safety Lockout. This transistor acts as a normally-open switch.

Safety Lockout:

This is borrowed in whole from www.doctronics.com, "retriggerable monostable timer"

The input signal is an RPM pulse train (0-10V), this goes through a voltage divider (0-5V), and an inverter (the monostable likes HI inputs).

The 555 timer is used to create a monostable timer.

The output (pin 3, green line) goes HI when the input (pin 2) has a falling edge.

Output is HI for 15 seconds (1.1*900K Ohms*15microF).

Red LED turns on to indicate Output is HI.

Basically, if there is a pulse train coming in, then the output goes HI for 15 seconds and stops you from enabling the relay. ( If it is already enabled, then there is no effect.)

The problem is that the 15 seconds starts from the first falling edge; additional pulses don't reset the timer.

Enter the "retrigger transistor"

Every time the input is LO (PNP) the capacitor is discharged and must slowly recharge.

This resets the 15-second timer after each pulse.

The actual circuit wired up on the bread board is shown below.

The rightmost button would be replaced by the RPM pulse train.

The center button would be replaced by a "normally closed switch"

And the left LED should be GREEN.

Bipolar Stepper Motor circuit

So about 5 years ago, a coworker was going to teach me electronics.

Starting with something simple: stepper motor controller.

List in hand, I bought diodes, resistors, and power MOSFETs. I scavenged a stepper from an old printer. And left in all in a drawer for 5 years.

Finally, I pulled it out of the drawer and started working on it.

The stepper motor turned out to be Bipolar Stepper Motor with 4 wires: 2 independent coils.

The drive circuit is basically an H-Bridge. This allows a low power/low voltage controller (like a PIC) to drive a high current/high voltage (1A @ 12-24V).

Power MOFSET

So I had a lot of trouble figuring out that the Source pin goes to low voltage (source of electrons) and the Drain pin goes to high voltage (absorbs electrons). Basic electricity, but it still took me a while.

Most of the circuits used transistors in lieu of MOSFETs or to control on/off ahead of MOSFETs. Eventually I found a simplified diagram using just MOSFETs.

Basic diagram:

Layout for breadboard:

My actual breadboard:

Of course all of this already exists in a simple IC, L293D Dual H-Bridge. Although, I suppose my set up can handle more current, the 16 pin IC is very clean.

Trouble producing the HEX file, redux

I busted out the system after a few week (okay, a month) of letting it collect dust.

I tried writing and compiling a simple modification to the last code...

and no luck?

I thought I fixed this!?

After much digging around (and some unpleasant grumbling) I found out that the Hi Tech PIC compiler was installed in "evaluation mode" and that license expired.

I reinstalled and things worked okay. But I am sure it reinstalled in "evaluation mode" again.

Ug

Baby blankets

We have a tradition:

whenever someone is about to have a baby,

my wife makes a baby blanket.

She has made 10 or so for various friends.

Well my brother and sister-in-law are about to having a bouncing baby "?" of their own. My wife thought that I should make it myself. Since I have not sewn anything in about 20 years, I was reluctant.

After 3 hours, a lot of coaching, and little help, I proudly present, my first baby blanket:

My brother and SIL have decorated the nursery with a safari theme; therefore, we chose a cotton print to match. We went with a soft yellow flannel backing.

Now I just have to pack and mail it before the kid goes off to college. (Procrastination runs in my family)

Trouble producing the HEX file

I wanted to compile and load a .hex file onto the PIC.

Powered up MPLAB IDE, modified the example source code:

     blink LED 1 instead of LED 0.

I finally got the compiler to work (I was having many issues, including the Virtual Store).

So, let's compile and load the .hex file... 

    Build Succeded!

but a message box pops up saying it couldn't load the .hex file.

Odd, but I can just do it manually.

wait, there is no .hex file!

I poured through the compiler options.  There was an option called FAKELOCAL...

Gee, that is suspicous, let's look there.

Sure enough, if I go to the HI-TECH Linker in Project->Build Options of the MPLAB IDE, there is a checkbox for Produce MPLAB debugging info.  Uncheck that and the FAKELOCAL goes away.

Viola, on the next compile, a .hex file appears!

Vista Virtual Store

Okay,

I just found something out: Windows Vista is stubborn about letting you save files in 

     C:\Program Files\...

Instead, it recreates the data files and directory structure in 

     C:\users\[USER]\app_data\local\virtual store\Program Files\...

Yes, Vista recreates a copy of all the files that you use from Program Files and hides it in some backwoods directory.

Vista then merges the program files in C:\Program Files\... and the data files in C:\...\Virtual Store\Program Files\... when you run an application.

According to the file browser in the application, the data files should be in C:\Program Files\...

Vista goes through great effort to conceal the fact that the data and program are in separate locations.

That's fine and dandy, but I couldn't find the .hex file that I just compiled (and neither could the loader)

Partial solution:

I ran the application with Run as Administrator and Win XP SP2 Compatibility Mode, and it appears to be working correctly now.

Well, that is 3 nights of my life I won't get back.