Featured Post

Sonified ELF signals from California, Hawaii and Virgin Island locations with 16x frequency shift

Much of my ELF measurement was done at my home using a 150' pine tree as antenna. During the recording, there was a power failure at 30s...

Saturday, November 8, 2008

New Kodak Z1015 IS digital camera

The picture below was taken with the Kodak Z1015 IS camera using maximum ISO: 6400, 3.1 Mpixel, maximum zoom: 420mm using a tripod, during a night game under the lights. I should have set the focus mode to center, it was in area mode, so the players in the foreground are in better focus then the kicker.

I have been using a borrowed Nikon D60 DSLR with a 200-500 telephoto lens to take pictures at my son's football games. While the sun was out, it took great pictures, only after it got dark out and the field lights did things get blurry. The owner of the camera was going on a trip, so I had to return the camera and had to stop being photographer for the team.

The game this week needed a photographer, so I broke down and bought a new Kodak Z1015 IS camera from Newegg, because they have very fast delivery. I was originally looking at a Costco.com ad for this camera and it seemed to have most of the features I needed. Especially the high ISO settings of 3200 and 6400, needed for the low light conditions under the lights. The lens also was pretty fast 2.8 - 5.4 for the 28 - 420 mm equivalent zoom range.

Most of the reviews for camera were good, except for the fact it can be slow to save the pictures, when in auto mode. There is suppose to be fixed in a firmware upgrade, where the post processing can be turned off, to speed click to click time. See below for more details.

I received the camera yesterday morning (Friday), after ordering on Thursday morning with next day delivery. New Egg had a bonus of adding a 2 gig SD card and a large camera bag, with plenty of room for the charger and cables.

First impressions:
1. I can hear image stabilization motors. They are not loud, but noticeable in a quiet place. It is nice to know it is working.

2. The manual focus adjustment is a little coarse, it automatically zooms the view finder 2x to help see the focus.

3. USB style charging cable with AC adapter (5V, 1A). I love this, even though they do not recommend connecting it to computer. I already have some 12VDC adapters, that may allow me to charge the camera in my car. I am also considering using making an auxiliary battery pack with a switching regulator and 9.6V battery pack. That way I can carry it in the camera bag to charge it during the game's half time without having to search for AC power.

Update: I had a TI step-down switching regulator evaluation board, that has a 5V DC output with input voltages between 10-18 V at 3 A. I am using it with 9.6 V nicad remote control battery packs as an auxiliary power source because it has a good efficiency . The camera actually pulls ~0.6 A while charging, less when turned on(?), so the regulator runs OK down to 9 V input. I can fit both the battery pack and regulator in the camera bag, so I can attach it during the game if needed.

1. The first thing that throw me for a loop is that the electronic view finder goes blank when the pictures are taken. I was used to the DSLR where the optical view finder would blank during the actual exposure, but even while the picture is being stored I could still follow the action. The Kodak would go blank until that picture is stored and the camera is ready to take the next picture. Even in burst mode, you can't see what you are actually taking pictures of.

2. There is a longer delay between shots. So between not seeing the action and having to wait and get a new focus lock, it is harder to take the picture of the pass and catch.

3. The motorized zoom buttons are on the same hand as the shutter release. But worse, you can not change the zoom while you hold down the shutter button to get focused. The Nikon had a manual zoom, which I would turn with my other hand and had complete control. So again it is slower to follow the action and get good framing.

4. In order to use the higher 3200 and 6400 ISO setting, you have to reduce the resolution to 3.1 M or below. The Nikon 200-500 had a higher aperture of 5 to 8, the Kodak 1015 with its 28–420 mm (35 mm equiv.) f/3.5–5.4 also gave it more of a speed advantage. So the players were less blurry and I could catch the ball in the are with only a little smearing. If you are going to use the flash, be sure to go back to a lower ISO.. In hindsight all I had to do was go to Auto mode.

5. The Kodak has a quick click to capture time, so once I got used to blanking, I could catch the ball in the air for laterals and fumbles.

6. I brought a tripod, but it turns out I forgot to remove the shoe from the other camera's telephoto lens. So I couldn't attach the camera to the tripod. My first couple of shots I tried free hand with the image stabilization. Even while it was still pretty light out, there was still some smearing. After a while I used the tripod by just holding the camera to it while shooting. This seemed to work well.

7. Battery life is hard to judge, because I had the firmware update problem, see below, so I couldn't turn off the camera to save power. I had also charged the battery during half time. In the 4th quarter I turned off the stabilization conserve power. I did make through the game with 191 shots, some with flash. I even took a few seconds of HD video, but I did't quite know what I was doing.

Firmware upgrade:
Since I was concerned with the click to click time, I downloaded the firmware update,. It is quite easy to install it even without loading the Easyshare software, as long as you can write to the SD card directly. You save the update in a SYSTEM directory and put the card back into the camera. When you cycle power to camera, it will detect the update and check the battery level then ask you if you want to upgrade.

Unfortunately for me, the update failed. So every time I turn the camera back on, it sees the update and if the battery is not completely charged, turns itself off. So when it was half time and it turned the camera off, it refused to come back on, until I could find a power plug on one of the light towers that worked. Because I didn't have a computer with an SD card adapter, I couldn't remove the file until I got home.

I have to admit it is a little unfair to compare this Kodak camera with a Nikon DSLR, that costs at least 3 times as much, but that was what I was used to. Although it will take some getting used to, this camera did perform well for taking picture of a night football game. It may miss some of the shots I would have captured using a DSLR camera, but the low light capabilities more then made up for it.

I will update this posting, again after the next game. One thing if found useful is the Setup->Orientation Sensor. Turning that one will automatically rot pictures taken with the camera vertical, so you don't have to go through them later and do it manually.

Thursday, August 7, 2008

Created new blog just for Open Stirling Engines

Having my personal stuff mixed in with the Stirling engine project was awkward, so I created a new blog just for the engines. It is http://openstirlingengine.blogspot.com and I will start to post my prototype status reports there. Please make comments on that site, rather the this one. Also please visit the official Open Stirling Engine project site


Tuesday, August 5, 2008

Upgraded HP/Compaq TC1100 hard disk problems

I just finished updating my old 40 gig drive with a 120 gig Fujitsu drive.

After trying several approaches to transfer the OS and files to the new drive and make it bootable, the solution was a freeware version of HDClone. I tried using Microsoft backup to copy the system and data to the new drive, but the disk was not bootable. Then I tried GPartEd, but it gave me errors and failed.

HDClone also reported errors in reading the data from my original disk, but gave the option to continue. After rebooting with the new drive, XP detected a hardware change and wanted to reboot again.

After that my system was back to "normal". The reason for the quotes is that Windows Explorer hangs when I try to get the properties of a disk drive. I would have to kill it using the task manager to restart it. I think I have bad sectors, but can't figure out how run Check Disk without bring up the properties for it.

Well at least I have a bunch of new space to download podcasts using Miro and room to add a Ruby on Rails development environment. I was at 97% and had to clean up all the time. Now I can wait a while before having to watch the Diggnation podcasts. Maybe download a movie or two.

Monday, July 14, 2008

Proposed new site for Open Stirling Engine project

I have created a google site for the project. It seems to have the features I need. It is at http://sites.google.com/site/openstirlingengine/Home check it out and give me feedback. Thanks.


4 cylinder Alpha Stirling engine almost complete

After working all weekend to build another half of the engine. It is almost complete. Unfortunately the first 2 cylinders have lost pressure, so I will have to track that down before I begin pressure testing. The 2 new ones seem to hold air well Got to go to my real job now.

Friday, July 4, 2008

Alpha Stirling engine protoype half done

I got 2 cylinders with push rods and cam assembled in a case. I changed the cam to a smaller one, cut from 1- 3/4" dia rod, so it is as smooth as glass. Pistons can now spin the shaft, now I need to add a flywheel to see if I can get it running. I have to be careful because it is still using polyethylene bags, so I have to limit the temperature.

Here is a picture of the partially completed prototype, but with the old cam.

Since I am using low pressure air as the working gas, the stresses on the push rods is not too bad. But I will need to add the cam follower guides so prevent the rods from bending when the press down on a inclined section of the cam with higher pressures.

I found a 7" flywheel pulley on my old vacuum pump. It had a 5/8" hole for the shaft, but I had a 1/2" bearing that had a 5/8" OD to adapt it. There is still not enough inertia to make on rev, so rather then getting a bigger flywheel, I've decided to complete the other 2 cylinders to balance the forces. Since they were always in the plan, might as well build them and test the entire unit. I will complicate matters having to apply heat and cold to 2 sets of cylinders. The other option would be to buy a larger flywheel from Grainger for $50. I guess I want to see it running before pouring more money into the project. I'll post a new picture soon of the assembled 2 cylinder version.

Friday, June 6, 2008

Sketchup model of 4 Cylinder section of alpha config

I finally got something I can show. This the Stirling engine design I would like to do as an open source project. It is modified alpha configuration that uses a cam instead of crank to drive the shaft. The horizontal cylinders are the hot ones and the vertical are the cold. There are still some pieces missing, in particular the push rods need a guide, otherwise they bend and bind in the hole through the case cover. There is also corner gussets in the case to hold the guides and to screw the end pieces to.

This is a 4 cylinder section. These sections are designed to stack along the shaft. The heads would just be extended to cover all the cylinders for each quadrants. The cam case pieces can just be extend too.

I am still learning Google Sketchup and had trouble making all the holes go through the head. I didn't finish added the head bolts and only installed one, it isn't even tightened. The head is suppose to be counter sank the the flat head bolts. The diagonal pipes are intended to be regenerators, that is why they are so wide. I am just going to use pressure hose for now. I still have to get the 3" wide 1/4" aluminum extrusion for the head. It can also be used for the case, since it is 3" deep, if you don't stack them. The case is intended to be sealed. A fly wheel will also be needed.

I am hoping to have the prototype to run with the cylinders pressurized to around 100 psi. The pistons are 2" diameter so the force pushing down on the push rod is over 300 lbs. That is one reason to have a sealed case. It could have back pressure to reduce the forces on the cam.

Now I can finish making the clear plastic prototype. It is made using mostly 3/8" thick sheet material. I am working on a spread sheet that would calculate the sized of the component based on other thicknesses.

Thursday, June 5, 2008

Diagam of sealed piston with pictures

Here is a diagram of the sealed piston that I am planning to use for the Stirling engine. I have exaggerated the gap to make drawing the bag easier. The kink in it on top of the piston is suppose to be the heat sealed end of the bag. A metal cap will be fitted over the cavity of the piston to hold it in place with a screw.

The area will be pressured with a working gas, most likely methane, so the bag will be tightly pressed against the cylinder and piston, so in those areas it will not feel the pressure. Only where the bag makes the U turn, will it have to support the pressure of the gas in the cylinder. With a small gap, the force on membrane will be on the order of 1/10th the tensile strength of the material.

Here are some pictures of my tests on the sealed piston.

Piston at bottom of cylinder. The plastic bag is tucked into the top of the piston, but not completely. Then it goes down 1/3 of the length and goes back up to the top of the cylinder.
It is under ~10 psi pressure.

As the piston is pushed into the cylinder, the bag's U-turn moves further down the piston.

Piston at top of cylinder. Note: bag should not extend past the end of the piston.

Stirling Engine Project Status - gettng bags

I finally got a response from the KNF and they are processing the sample request.

I downloaded Sketchup from Google and begun making a 3D CAD model of the design. I should have model done this weekend. For now my priority is to start fabricating a second cylinder and piston assembly, so I will be ready when I get the bags for the seals. Also assemble the cam case. I am using acrylic for the heads for now, so I can see the top of piston. If the seals work, then I will switch to aluminum and tap them for 1/4" pressure hose connections.

I work on the machining in the evening because it makes noise and switch to assembly and software at night. I will try to take some pictures this time as I make the second set. The 3D modeling really helped, by showing where to put the head bolts, so they don't get in the way when assembling the cam case. There is no crank in this design, only a cam. This makes it possible to have up to four cylinders, two hot and two cold in a single radial plane. The shaft is straight through, The plan would be stack four packs to increase the total power of the engine. The current heads are just flat pieces that can be shared between adjacent layers of the stack.

The goal here is to keep the tops of the heads as flat as possible to keep the heat exchanger components simple to apply.

Initial testing will be on the minimum two cylinder configuration using low pressure air as the working gas. Once I up the pressure, we will need the opposing cylinders to balance the forces. The piston is > 3 sq in, so 100 psi is over 300 lb force on the cam. My main problem is providing support for the cam follower, so it doesn't jam or bend on the curved portions of its travels. I think I have that problem solved, just more stuff to build.

I am not have mentioned that assembling the seal is quite difficult. The bag material has to be stretched from under 2" in diameter over the outside of the cylinder which is 2 1/4 diameter. I will have to do some heat forming of the bag for production, so it all goes together much easier.

Tuesday, June 3, 2008

Looking for a few good bags

So far I have only found polyethylene bags in my area. I called every plastic bag supplier in my area.

Here is a request I sent to a Nylon supplier.

I am working on a prototype Stirling engine, that requires sealed pistons. I am looking for thin plastic film material with high temperature strength, fold crack resistance and low cost.

For my initial testing the working temperature will only be 210 degrees F and am building it out of acrylic plastic. This way it will be easy to keep an eye on the seals and to demonstrate the principles. Your Kenylon products seem like a good fit.

My plan is publish the plans for the engine Open Source using standard sized parts, so others could contribute and to speed the development. I will be making sealed piston/cylinder assemblies available as product, since based on my current experience, getting the plastic material with the correct properties and dimensions has not been easy. Each engine would have at least 4 cylinders, I am expecting that there will be a significant failure rate of the seals, so they may have to be replaced after a short period of time, until we can find the proper balance between thickness, pressure and folding life.

I almost have the prototype engine complete, except for the seals.

Right now I am using polyethylene bags, but they don't maintain their shape very well and begin leaking.
I need a stronger material.

The width is somewhat critical, so the bag fits snuggly around the piston which is 1.95" in diameter. A 3" bag is a little snug but should work. I am considering going to 1.90" diameter, because it is standard size for an aluminum tube, which I will switch to for production. In production I am expecting to have to reshape the bags, to different diameters in each section, to make assembly easier. Once the cylinder is under pressure the bag will stretch to fill the gap. So for now it just takes me more time get it fitted over the larger cylinder OD to make the seal.

I need at least 4 pcs of 3" wide nylon tube bags that have seamless sides and a heat sealed bottom. The length is 6" minimum. If I could get then with different thicknesses that would be great, but 4mil is a good start. getting 2 and 6 mil sample bags would be great.

Monday, May 26, 2008

Stirling Engine Project Status

I now have the piston/cylinder assembly ready for testing. On Friday I found a distributer of plastic bags near where I work and got 3 samples, 3" x 6" flat polyethylene bags:
1- 2 mil thick
1- 4 mils thick
1- 6 mils thick.

The actual size of the bags varied and the thin one split down the side as I tried to fit if over the piston. The 4 mil bag was oversize so while it easily fit over the piston, it was too loose to properly fit into the cylinder with creating creases.

The 6 mill bag was tight and had to be stretched over the piston. Get it into the cylinder was easy, but getting it to fold back over the piston was tough. The final step of stretching it over the outside of the cylinder took hours. I think I have a better technique now, but with the bag already stretched out it may be just easier.

The bag got damaged near the sealed end of the bag, so I had to patch it with scotch tape.

This bag seems too thick, because it would rather slide in cylinder rather then roll. It seems to work OK when under pressure, but the seal is still not good. It could be more leaks through the bag or the top cylinder to head seal.

Conclusion: The current bag is both the wrong material and not the right size. But it does seem like it could work. Still need to find a seamless 2" diameter Nylon bag, which would 3" across when flat. I man need to do some custom reforming of the bag to get to be easier to install.

Monday, May 19, 2008

Open source Stirling engine project

I started to research Stirling engines. There are several different configurations. Some have quite complex gearing and levers arrangements. One version I saw on the Stirling Engine Wikipeda page was called an alpha configuration. It seemed like a much similar design, with two pistons that are stoke 90 degrees apart. The crankshaft is very similar to a internal combustion engine.

One of the problems with creating a powerful Stirling engine is that the working gas has to be under pressure usually several atmospheres. The working gas also should be very light, like hydrogen, helium or methane. While air and nitrogen can work, but it reduces the amount of power that can be extract per cycle. Hydrogen is the best, but it is difficult to contain since it can escape through tiny gaps around the piston seals and diffuse right through metal.

I think I have come up with a sealed arrangement that uses a flexible membrane to provide a more positive seal. I made a small model today using old plastic cylindrical medicine jars. It was somewhat difficult to assemble it because the diameter of the plastic bag I used was slightly smaller then the piston. So it took a lot of fiddling to get bag into position. It seem to work.
The area of the plastic that is not supported by either the cylinder or the piston is very small. Like skinny balloon, it takes a lot more pressure to get it to stretch.

Now that it looks like I can get an inexpensive sealed piston, that doesn't require precision machining. I think I can make a very simple and cheap engine.

My goal is to make plans for several different engines using standard parts made from easier to obtain sources like aluminum or steel pipe. Since the piston actually has to be somewhat smaller then the cylinder the tolerances are quite large.

The current design I am working on is more a demonstration unit. So it will be made mostly from clear plastic tubes, rods and sheets. My plan is to use steam to as the heat source and ice water for the cold side cooling. This will limit the thermal efficiency, but it will allow me to see the how well the sealing membranes are holding up.

In initial tests I will use air as the working gas at only a few atmospheres. But my plan is switch first to natural gas, methane then hydrogen. Any gas that diffuses through the membrane seals would be captured in the sealed crankcase, it could be used to contribute to the heat source.

In this design, both hot and cold pistons and cylinders can be made identical so as to reduce number of different parts. This would allow some economies of scale.

The hot and cold cylinder pair could be ganged to make longer engine. When ganging the piston pairs they should be set to balance the forces from the opposing piston set. Because the pistons are always under pressure, the force from one set should counter act the force from the other set. In a four cylinder engine, they should 180 out of phase from each other.

The current design is based on sketches I found on the web and I am scaling it so the cylinder has a 2 inch diameter. I chose this size because the cost of the components is not to high and so the cylinder walls can be thin. There are metal tubes and aerosol cans with similar dimensions that can be used in production unit.

The heads will be made from a flat piece of metal. Either aluminum or brass about 1/4 inch thick. The cylinders are simply pressed between the head and the plastic crankcase housing, with long bolts. Since the heads are where the heat or cold is applied, it pretty much has to metal. Since I am planning on directing flame at the hot heads, I am going to make them horizontal cylinders so the head would be vertical even with a horizontal shafted engine. For eight and twelve cylinder engines, it may have a vertical shaft and the head would be a single unit for of each adjacent cylinder in the quadrant.

I am also thinking of modulating the burners, so it is off during the "exhaust" stroke of the hot cylinder. Why heat it, just to send it to the cold cylinder?

The heads will have a standard threaded fitting that connects to the re generator pipe. It will also be plastic for now and filled with a series of short bundles of small diameter metal tubes. These should be assembled so the holes align, to improve gas flow.

Since making a crankshaft for more then 2 cylinders is non-trivial, I am thinking of using a cam instead. Initially it will just be an eccentric circle mounted on the flywheel. I chose this because the each of cylinders are under pressure and will press against the crank shaft making it very difficult to turn. With the cam arrangement it is easier to add another set of pistons 180 degrees out of phase from the first pair. The forces from these pistons will cancel out. The cam allows all the pistons to be in the same plane. That way we can still add more sets without a complicated crankshaft. Just slide more cams onto a straight shaft. The down side is now the flywheel has to be at least twice the diameter of what the crank would have been. Since the forces on the cam are quite large even with moderate pressure, I am planning on pressurizing the cam case. This will require changing cam case round and having to make the bases of the cylinders curved so they seal properly.

Because the demonstration unit will be made mostly of clear plastic, it will not have very much power, because heating and cooling will mainly be done by the heads and not the cylinders.
Since all the parts will have standard dimensions, the plastic parts could be swapped out an replaced with metal ones.

I still have to make some scaled drawings of what to build, so I can buy the plastic parts from Tap Plastics. I also put a request for a quote for a Teflon piston seal. Sort of a big condom for the piston.

I am hoping to make this project be open source, so we can each share improvements for each of the components. Since the parts will mostly be a standard sizes, we should be able to swap out components when they ware out or when a better one becomes available.

Thursday, February 14, 2008

Emerson EM230 Bluetooth Headset

I bought this headset several months ago, for my wife's Samsung Sync. But she never used it because it only has 1 button in addition to the volume up and down buttons. Because it has so few keys, it takes some combinations or timed presses to get all the functions. Since then I finally got a BT adapter for my tablet-PC and use with Skype and Teamspeak voice over IP calls.

Here are the key sequences from the manual. That way I can check this site from my phone to see what they are:

Keys: MFB, Vol+ and Vol-

Turn on: Press and hold MFB 2 seconds
Turn off: Press and hold MFB 5 seconds
Answer/Make/end call: short MFB press
Reject call: MFB 2 seconds
Transfer call: Vol+ 5 seconds
Mute:MFB & Vol+ same time
Hold/return to call: Press and hold Vol- 2 seconds
Pairing: Press and hold MFB & Vol- 2 seconds,
blue and red leds flash alternately while searching.

The headset can only hold 8 devices codes, so far I have used 5.
After that I have to figure out how to reset the device.

Low battery indication: beep in headset each minute, red led flashes 4 s