Well, I recently recieved my boards back from ap circuits in Calgary and I’m pleased with the result. I kind of fucked up by ordering 4 of the same board and not 2 of the control board and 2 power boards. Oh well! I can use the current boards for the new ones. Anyways, here are some images of the board.
The two boards together, unpopulated and populated
The board, populate with SMD's
After being apprised of an issue with heat transfer through PCB traces, being the stubborn idiot I am, I had to try and solve the problem. The issue is with a particular PCB that has a cutout section with a thermistor placed in a partially isolated section within the enclosure, unfortunately the traces themselves are serving as a heat transfer conduit especially so since copper is a particularly good conductor of heat.
After thinking about it for a while I came up with a couple of ideas like calibrating the calculated output to accommodate for the temperature discrepancy, however that probably wouldn’t work without a second thermistor closer to the heat source, accounting for the difference. Another idea I had was to use an infrared thermopile but they’re kind of large and expensive and would require a heat channel mounted above it to prevent measuring the temperature of the case.
After thinking for a while about it, the simplest answer I could come up with would be a heatsink to mitigate the heat transferred to the thermistor. While it is theoretically impossible to totally remove all heat difference, I believe that a large portion of the heat transfer can be eliminated. So I wanted to see if heatsinks actually help equalize heat much at all so I devised a bit of a rough experiment.
The Experiment
I decided the quickest way to test this would be with materials I already had. I have a selection of thermistors so I used a glass axial thermistor.
This is the thermistor board used in the experiment. the thermal leads aren't attached.
The circuit used for the test. Beautifully illustrated
This is the board with the two 22AWG leads attached.
I also performed the test with the leads closer to the thermistor.
| Test Type | Voltage Recorded |
|---|---|
| No leads, ambient | 438mV |
| With Leads, ambient | 438mV |
| Pressing thumb on thermistor ~33.1c | 554mV |
| Heat with long leads, No sink | 496mV |
| Heat with short leads, No sink | 625mV |
| Heat w/ long leads, w/ sink | 476mV |
| Heat w/ short leads, w/ sink | 544mV |
.
The thermal isolation idea. By placing a heatsink on the exposed traces one could mitigate the heat transferred to the thermistor.
This post is simply to show how neat the FDM process is. FDM stands for Fused Deposition Modeling and is a neat tool for prototyping plastic parts. I was able to see the results of FDM after a customer had one of my models done with the process, he was nice enough to let me take some pics of it 
. Frankly I think this kind of prototyping opens up a wide variety of interesting possibilities in terms of being able to develop plastic enclosures and various other mechanical projects.
Here are some images:
The two peices in FDM, this is a deposited ABS IIRC.
I altered the levels to show how the process fills in non critical areas. Of course it would depend on the machine performing the action.
Corner Detail FDM
This is a very interesting process, hopefully I can make use of it in the future.
Here’s the wikipedia article http://en.wikipedia.org/wiki/Fused_deposition_modeling
Well, it’s been a busy few weeks since I left the business training program. Thankfully I have some work lined up and things may go well for the short-term. For the last while I was working on the design for a plastic enclosure for a customer. Everything went quite well and the customer is an absolute joy to work for/with. Based on a board and taking cues from other ideas, I drafted a simple enclosure for a device. Here are some pictures of the enclosure.
Worked out well…
Also, I am now continuing my foray into the automation stormer viscometer as well as my auditory camera level. Things should go quite well if I bust my ass…
I’ve finally had some time to put together my website for my business. 8mtech.com is online and has most of the pages complete. I’ve decided to keep the layout very simple and I’ll eventually flesh out the theme a little better.
As an aside, my business cards came in, they were very nice. print100 based out of Hong Kong did a good job. $30 for 300 cards with corner cutting, matte finish and double-side colour. Very nice!
Anyways, if anyone wants a freelance inventor or a draft monkey, give me a call!
Well, the past few weeks have been eventful and interesting. I’ve been busy and school is almost over. I’ve had a few things on the go and I’ve come up with some interesting ideas and implementations. Sorry for the lack of images in this post but I’ve been lazy taking them.
The DIY Measuring arm
This idea came from the need to build a measuring arm at a very low cost. I simply used some wood and some regular linear potentiometers.
The cheap and quick measuring arm, this image doesn't show the wiring or the board behind it.
Anyways, things are going well but it’s a lot of birds in the bush and none in the hand. I’m just writing to keep a log of what’s happening
Well, I’ve been at Microbusiness Training center for 5 weeks now and I’ve been working as well. Soon, Eight-M Technical Services will be operational and i’ll be working for myself.
I’ve set up a new domain with my Dreamhost account. The site’s URL is http://8mtech.com. As of posting this, the site isn’t ready, but it will be soon.
The viscometer is being tested by Endura right now and here’s what it looks like, it’s a youtube video, be warned.
my logo for 8m
Was bored for a little while today so I made a quick program in Freebasic to produce a Sierpinski Triangle and a some sort of pentagonal fractal. This little program uses the chaos game method to produce it.
seirpinski triangle
seirpinski at 5
Well, it’s been a long road but I’m almost at the finish line in terms of the majority of development. All of the parts are mostly made and I’ll begin programming very soon, most of which has been done already or figured out in advance.
Firstly, I started with the board. I had to build it from scratch because I’m not certain of they’ll want more features or different ones, also I simply don’t have the funds to get the printed boards made, those will fit in the top of the unit below the LCD and reflection switch.
viscometer test board with lcd display
Viscometer, assembled on base
Viscometer with sensor in hand
While developing the in-process stormer viscometer, one of my goals is to allow the end user to calibrate the device with 3 fluids of known viscosity. With a bit of help from mathematica, I’ve found the formula and for whoever wants it, it’s posted, also for my own future edification. This formula is meant to convert 3 data points of the form {X1,Y1},{X2,Y2},{X3,Y3} into a form of ax^2+bx+c=y. This is probably the fastest way to do this kind of operation on a microcontroller. Here’s an image of the formula
Reverse Quadratic from data
also, here’s a dirty FreeBasic program using it. regress-3point.bas
Also, for fun I decided to do a cubic version. This is in the form of 4 data points {X1,Y1},{X2,Y2},… converting to ax^3+bx^2+cx+d=y
Cubic equation inverse
You gotta love Mathematica!!!
I thought I would have nothing to post but I do I guess. I’ve felt the need to really expedite this project now that I am starting a business. I have done a few of the mechanical things associated with it after a major redesign. Today I have completed the design of the board and despite it’s sloppiness, I’m happy it’s done. Now to get it made.
Viscometer Board 3D View
Viscometer Board traces
Machining the block
Phenolic Block Finished
Coming along, main block and holders finished
Anyways, let’s hope she all works out in the end.
Well, no new project pictures or anything. Summer is almost here and I’m pretty happy about that. I’m going to start at a training course for 8 weeks starting May 11.
The program itself is funded through the Canadian Government or Employment Insurance. This program is geared for people who wish to start their own business but lack the experience starting one. This program also has a 4 month post-class coaching period. From what I understand, they assist with the minutia of business and get you hooked up with financing. This program also allows one to keep collecting EI through the 6 months of the training, but not afterwards.
My idea in this case in terms of starting a business is a nebulous one at best at the moment, however, I think that by lending my skills as a machinist and programmer and technical dude, hopefully I can eke out a living or perhaps even a prosperous business in these difficult economic times.
I think that this program will help give me an introduction to the business skills I lack in abundance. Anyways, hopefully tomorrow will be a sunny day, I want to do my full report on minolta md lenses.
Well, my servos have all come in for a project I’ve been working on. These ones being some cheap Chinese servos that I picked up off Ebay. Here’s a photo of one of them.
Chinese 9G RC Servo Photo
Chinese 9G RC Servo drawing
Chinese 9G RC Servo Solid
As the project progresses I’ll review the functionality of the servos. After I had ordered them I had read that they are susceptible to outside interference, especially from the likes of human contact around the housing. From what I read, this made the servo “Freak out”. We’ll see I guess, I’m going to make a standard testbed circuit for testing anyways.
So, anyways, for anyone who wants it the drawing, here’s the PDF
Hopefully someone will find it useful.
It’s been a while since I’ve worked at full steam on the viscometer project. Though now a long way from it’s DIY roots I am making this new version from mostly Aluminum, Phenolic, Nylon and Low Density PolyEthylene. I had to scrap the last version since it would have been too difficult to actually assemble, this one is a little different in it’s overall size and assembly.
In short, I’ve finished the reverse engineering of an enclosure. It was more work than I expected but all of the draft angles check out and the drawing is workable for changes. Here are some pictures.
whew! Doesn’t look like much but it was a bit of a challenge. Looking forward to more challenging drawing projects.
Since my design was accepted in terms of moving ahead on a prototype, I’ve been working first on the board design. I have decided to abandon the PIC18F2620 in favour of the 18F4685. The reason for this change over is due to the fact that the 18f2620 doesn’t have enough I/O to handle the addition of two analog channels and four I/O for RS-485 communication.
This post is more for my own edification and to help me sort out my thoughts on this issue. I suppose for the sake of following my train of thought while sitting here, I’ll outline the specifications, as I think of them.
Overall feature set:
PWM output for 6-24V DC motor.
RS-485 Out – Rec enabled
LCD out
16 key keypad in
2 temperature sensors
LED indicators for power/error
Serial out for RS-232
Input for external reflection sensor
2 inputs for timing sensors
So, thats 1+4+6+8+2+2+1+1+2 = 27 inputs
I found some nice Molex headers that are single row, .100 pitch and is latched. Typically I use the friction based header and housings but it needs to be secure inside the housing and thus I’m trying out the new set. Also I’m going to use vertical out terminal blocks in order to save space inside the unit but not necessarily on the board.
I’m also considering adding an RS-232 port along side the board.
Hopefully this will be the final hurrah!
Now I have to find some suitable DC gearmotors for the viscometer. here are some links, for reference, to some suitable gear motors.
A 300 RPM one from batteryspace, a little small, good low cost though.
A little pricier. This is a cheap chinese one that is on the current prototype.
Not really useful but might have some other uses
Have no idea about these but seems to have a good selection.
Well, this has a been a long few days of work. I have created the ideal rotary viscometer in both terms of price and repeatability. Now, this idea is nothing new but I’m simply happy that it works. I guess it’d be prudent to go in to how it works…
How it works:
The concept is simple. you have a shaft that is separated by a spring, in this case two plastic cups connected by a ball bearing with rods sticking out one side. This shaft is driven by a small gear motor and a set of paddles is attached to the other end. While this is rotating, the difference in the driven and the resisted side is measured with some form of instrument be it a hall effect sensor or a slot type optical transducer.
Viscometer and stand
Well, as far as materials are concerned, for the prototype I used blocks of polyethylene to support both the motor and the shafts. The material has pretty low friction properties at low loads and thus I used it as the bearing on the bottom. The actual difference mechanism is made from a high density plastic. I would probably use this material again as it’s light, rugged and easy to machine. For the real unit, I may still use this plastic as it is more than strong enough and it’s easy to machine.
As for the drive I used a design similar to the older designs with PWM motor output, serial output, keyboard input, LCD out and 2 channels of input. This is all controlled with a PIC18F2620 which is more than enough for it’s needs.
The motor itself is a Hsiang Neng gearmotor running at 12 volts. It’s a piece of shit but that’s not important at this stage of the game.
Motor and sensor
1. RS-485 Out
2. KU and Cp out
3. Multi-fluid calibration, this feature allows the user to select fluids of any KU value and calibrate the unit by entering them in.
4. Easy to use menus. Too often have I seen automation stuff that’s unintuitive. This hould be easy for the operator to understand and easy for the people to use.
5. Speed selection, so that you can use under-powered motors.
Anyways, here’s a gallery of some of the pictures of what could be a DIY stormer viscometer.
Now that I’m working on the viscometer, again, for Endura; I have come up with a few cheap ways of producing the needed results. They may work, they may not. Anyways, pictures and drawings are forthcoming.
For the last few days I’ve been working on the electrical portion of an astrophotography mount for my camera. The mechanical portions were built by my father and I’m handling the electronic portion of the device. Basically, for those who don’t know, this device is designed to allow one to take long exposures of the stars without them blurring due to them moving across the sky. This device moves the camera in such a way that allows for said movement.
Originally, my father and I spent a day working on both the frame and the electronic portions of the unit. I quickly whipped one up with a protoboard I had laying around and a PIC16F690. I used an SN754410NE H-Bridge driver for this design as well. Unfortunately we didn’t finish the project that day, and I wasn’t keen on programming the PIC having to pull it out of the IC socket every time I wanted to test it.
The original defunct board. This board was omitted due to the fact that it had no ICSP provisions.
First, I took some Stripboard and planned out the pinouts and connections. Stripboard (or veroboard) is my favorite since it’s so damned easy to plan. Despite there being a great many other protoboards out there, veroboard has been the most useful, for me anyways.
Planning it out
Starting the board
Halfway done
Board pretty much complete
Astrophotography electrics working with keypad, LCD and stepper motor
Electrics in Enclosure
Anyways, I’ll report further progress, as usual, on my blog here.
Here are some interesting links
http://www.keteu.org/~haunma/proj/barndoor/
http://www.cs.uiowa.edu/~jones/step/types.html
Comment if you wish.
I bought a couple of keypads of Ebay some time ago and since they were so nice, I decided to use them in my latest project. Since there are no data sheets for this, that I could find, I checked the wiring myself. The unit is from Bally systems, made by ACT and has P/N 105123D
Here are a couple of images of the unit.
And here’s a connection table. Keep in mind that the connections range in resistances from 30 to 100 Ohms.
| Pin 1 | Pin 2 | Pin 3 | |
| Pin 4 | CLR | 0 | ENT |
| Pin 5 | 3 | 6 | 9 |
| Pin 6 | 2 | 5 | 8 |
| Pin 7 | 1 | 4 | 7 |
Many years ago I used to make maps for Doom. There is still a community going strong for making maps and now with modern source ports and editors, sometimes I dabble in making a new maps. Anyways, here are some screen shots from what I made. I’m certainly not very good anymore, it takes practice to make neat looking maps.
Maybe I’ll make a full map one of these days, though, looking at some of the elaborate maps that the community is putting out, I’m not sure I’d have the time to compete with such standards. It’s fun nonetheless.
Since I’ve started playing around with writing games again, I’ve been interested in old school sounds. These things can be hard to come by these days since a lot of the older sounds were pure square and triangle waves.
I found a couple of programs for creating these sounds. Both are windows programs
.
Well, out of boredom I’ve created a little game called Astrosmasher. Nothing special really, I just wanted to see if I could make a game look like an old Atari game. I think I succeeded in some ways
Astrosmasher is a partial clone of an older colecovision game bit I got bored with it pretty quickly, I think I’d like to write games that are a little more fun despite the fact that I have no artistic ability.
Anyways, here are some screen shots and a like to the game. The game requires windows 2000+.
Consider this game, for the most part, incomplete. I got bored with the idea and made it workable. It is a hard game though. My high score thus far is 35100. Give ‘er a shot. 
Well, It’s been a number of days since I built the unit and all’s been tested. Here is a picture of some of the data from my living room over the past several days. The purplish is the temperature and the lighter one is the ambient light. You can see that as the light levels get higher, the furnace stops, thus the temperature stops fluctuating.
The living room temperature as seen over 6 days
Sorry about the small scale of the temperature graph, the graphing program is still a work in progress.
So, since I’m really bored I decided to build a device that tracks ambient temperature and light levels. While this may not seem very interesting, I suspect the relationship between the two, while not directly linked, will be interesting especially when placed outside. Well, I suppose I’ll put a few pictures up and outline some of the stages I went through to get it to this point.
1. Prototyping.
The initial version of the sensor, using older stuff from viscometer project.
Cup o' snow to check and see if the Opamp is biased correctly
Temperature check with the IR gage
The voltages swung just fine with a bit of extra range. I have about 50C to work with in range, good enough.
3. Making the board. For this I used a board from measurexplorer. I have tons of these but haven’t had much luck using them. The only ones that have worked well for me are the ones with 3 holes per pad. Anyways, here are some pictures.
Start of prototyping the board
Finished Sensor board with both light sensing and temperature sensing
Anyways, This board took me a couple hours to make but it works well and required no rework, thankfully. You can see both the LM335X (TO-92) and the CDS for sensing the light. This board interfaces to an RS232 board that I’ve made and that I use for some of my other projects.
4. Getting ‘er running. While the unit itself is already programmed in terms of the MCU. it needs some adjusting for voltage on the pot and that’s about it. now to affix it to something so it doesn’t move around.
RS232 and Sensors glued to a board
Tracking it on the computer
As you can see, I simply used hot glue to affix both the RS232 board and the sensor board to the block of wood. Its a temporary arrangement while I come up with a good enclosure for outside. I brought my old laptop out into service for this project, works well just for collecting data.
Anyways, here are some images of some collected data.
Living room temperatures (click to see description)
Basement (click to see description)
Well, so far so good. Now I’ll make the enclosure for outside and improve the sampling. hopefully I can leave it out all spring/summer and see the patterns.
Well, I was trying to solder some extra thick peizo material, having very little luck when I realized that this could be solved very easily with some sort of conductive adhesive. So I set out to make some. I’m posting the steps for making a conductive adhesive for posterity and in case anyone needs to know. It’s not difficult though I have tried a few different methods and this one is the best.
1. Find your glue, preferably one that requires drying or curing, not anaerobic adhesives like Loctite (cyanoacrylate). I tried a couple of versions of Loctite and found that the conductive medium would merely clump together, making an oatmeal-glue. You can use adhesives like Rubber cement, 2 part epoxy or even white glue (polyvinyl acetate).
In this case I used two-part epoxy. It has a long cure time and its fairly rigid.
A small sample of the epoxy
2. Prepare the medium. In this case I used a conductive graphite powder and iron filings. If you’re going to use iron filings, magnetize them first by letting them rub on a magnet, then force them off and into the graphite mixture. Beware that using a water based glue can make the iron filings oxidize.
Anyways, if you don’t have any graphite on hand you can crush up some pencil leads in a crucible or on something that will allow you to make the graphite as fine as possible. And in the event of not having any iron filings, like me, do what I did, grind or file down a piece of steel or an iron nail. make sure they’re magnetic.
This is the graphite/iron mixture
Now, you may ask “Why iron, and why magnetize it?” Well, the iron provides low resistance paths through the adhesive and when you apply a magnetic field to the iron filings, they align themselves to the field, thus you can create a lower resistance path. I’ve reduced the resistance with this method by tens of KOhms based on the little I’ve done this so far, your results may vary.
3. Mix the glue and medium. Well this is a pretty simple step. The only thing you’ll many though is to add enough of the medium to make the overall adhesive almost clumpy, mixed to the point of saturation. This way you can ensure conductance.
This is the mixed version of the glue/graphite/iron filings
4. Application of the glue. Simply apply the glue however you want, wherever you want. You’ll get less resistance if you place the two conductors as close to each other as possible though. Also, you’ll want to place one or two magnets, polarity aligned to the connections zones, near the adhesive. This will make the iron (if you used it) move slowly into lengthwise position between the two conductors.
This is the peice of peizo material attached with epoxy.
Anyways, to be honest, I’ve only tried this formula a few times and did it entirely by eye, therefore I can’t give any exact values. But, thus far it works for me. If it works or doesn’t work for anyone else, feel free to comment.
A while back I bought some lcd displays from a dude on Ebay. After I recieved them I found that I couldn’t find the appropriate documentation. Well I found some documentation so I post it here for posterity or if anyone else wants it.
ktms1201
upd7225-ap-note
s14308ej6v1ds00
These are 12 position, 7 segment displays. They may come in handy someday so I’ll try them out later.
KTMS1201 from Modulehouse
UPD7725 controller
I was a little bored today so I decided to draw a valve. While the dimensions are entirely drawn from my head and the valve itself wouldn’t be very efficient, I like the look of gas compressor valves. It took me a couple of hours to draw but they look OK.
I didn’t tag them or describe them. There is a seat, a guard and a valve plate. I omitted the dowel pin, bolt, center nub and lock nut. I just wanted to see what it looked like in solids.
Been working on a new version of the rotary viscometer, after many design changes, the result is this. A rotary viscometer bridged with a rotary reaction strain gage. Guess it’ll work. Here are some pictures.
I’d say a bit more but I’ll wait until the design is a little more fleshed out, and of course, remember that this design isn’t finished since the motor at the back obviously doesn’t float in mid-air.
For the last while I’ve been in a bit of a creative funk. Troubles at work and the the weather have made it difficult to concentrate on the things that I like. Anyways, perhaps while I have some time off I might make use of it to do some stuff. Don’t know really.
That brings me to my next topic. What I should do.
Firstly, I think I’m going to start taking more pictures of Edmonton again and post them on Panoramio again. Frankly, this is the reason I started taking pictures in the first place was to provide images of Edmonton for whoever wanted to look and explore both the nice parts and boring parts of our city.
Secondly, I’ll finish that fucking clock. Really not much more to do it it, just make it so you can set the time.
Thirdly, focus on building a working vibratory viscometer. It’s the ideal way to measure Krebs units in an environment as harsh as paints and it will be substantially cheaper.
Anyways, End of Line.
Well, I’ve been looking around at torque sensors and found some interesting information. For one though, they are NOT cheap. Keep in mind that these are higher sensitivity sensors but it doesn’t seem to have an overwhelming bearing on the overall price. for example.
Optical, high sensitivity sensor, ~$6000
Magneto-elastic sensor, ~$2000
Strain gage based, ~$4300
While this is expected, it’s still quite a cost on a per-unit basis. interesting.
Another little tid-bit I picked up is this.
Magneto-Elastic sensor document
Anyways, I’ll keep looking for a cheaper unit, though, I doubt I’ll find one cheaper than the unit I developed. Perhaps I’ll machine a small enclosure with precision bearings and develop a more robust and practical design. I have some conductive graphite for the brushes in order to reduce noise and the brushes could be replaceable. Might try it.
Well, for the past little while, I’ve been working on a bizarre clock made with LEDs glued into a dollar-store cookie sheet. I got the idea just out of the blue and decided that it would be fun to build. Now, it’s nearing completion so I figured it’d be prudent to document the miserable contraption. I guess I should go through the steps it took to get this thing running.
First, I took one of those dollar store cookie sheets and drilled it through for 40 LEDs. 12 for the hours, 12 for the minutes, 5 for the seconds, 5 more for the div/5 minutes and five more for the outside and the PM light.
Drilling it wasn’t much fun but, when it was finished, I started to insert the LEDs with the grounds all towards the outside of their respective circle. Then I mixed up some epoxy and drizzled it over the backs of the LED’s. Unfortunately, the epoxy didn’t hold very well on the other epoxy surfaces so I used hot glue to tie them down.
As you can see, I labeled it in reverse of the other side so that I could get ‘er working. Thus started the long job of soldering the whole thing.
The image show isn’t the complete one, but it took me several hours to solder it all together. I used 7 groups of 6 LEDs in order to display the image. In this case I used the 7 groups for the duty cycle, thus a 1/7 duty cycle was used. Each of the 7 groups is fed ground through an MPSA13 Darlington transistor. Here’s a picture of the board that controls it.
Pretty fucking ugly, I know. But it works and I used an MCU (PIC18F4685) that was a little overkill but that’s fine, I’ve got quite a few of those. Anyways, so far so good, though it seems a little impractical as a clock and I think I set the rings of the minutes and hours too close together. Oh well.
So, after doing a bunch of work on the rotary strain gage it’s been declared incorrect. Oh well. Here’s the new concept, although not my own idea, were going to rebuild the entire concept around the notion of a dynomometer. First we’re going to place the motor inside of a housing that allows the motor to move freely with the help of large ring bearings, then we’re going to bind the motor in place with load cells.
While this concept may work, I feel as though it’s lower end repeatability and accuracy will be compromised and will be greatly subject to temperature differences as the bearings heat and cool from ambient and mechanical sources. But perhaps I’ll be proven incorrect.
Here are some images of the idea.
I’m going to keep working on my own sensor design in the meantime, it may come in handy someday.
Well, it’s been a little while since the last update, I suppose I should have stated something sooner. So far, the device seems to work but now I have mechanical problems. Friction on the top is preventing the load from being sensed at the paddles. Plus, the strain gages, I believe, are placed improperly. While it looks as though one side gets compressed and the other side gets stretched, I am thinking that this is not the case.
Unfortunately what that means is that the strain gages are counteracting each other, thus the voltage difference is too small to detect effectively.
Gonna design a new one with only two strain gages.
It hasn’t been long since my last update about this thing but I’ve made some progress as far as making the unit into a single board. I simply used the AD7705B as I suspected it work work great for this application. I’ve been playing around with reducing the amount of noise coming from the sensor but random fields are causing the ad7705 to produce strange numbers, even when my hand just gets close to the unit. Here are some pictures of the unit.
Messy ugly board for rotary strain gage
Rotary Strain Gage being tested
Thus far it seems to work though, at least when tested with a multimeter. Sadly though, it seems impossible to test it with the oscilloscope because it uses the same ground as the power supply, damnit!
A while back I purchased a 200mm f4. Rokkor lens off EBay for pretty cheap, like 40 bucks total. Since then, I haven’t really been taking any photos and thus haven’t been able to get a good feel for the lens. Tonight I decided to brave the cold and take some night shots with the camera, nothing special, just some far away downtown shots with lights incident to the lens.
Sony A300 with 200mm Rokkor lens attached
Night Shot with 200mm Rokkor, Level corrected
Tree shot with 200mm Rokkor Lens
As you can see with the downtown image, it’s level corrected, the wind was so strong that long exposures tended to make the focus look poor, when in fact it was shaking. The tree image is also level corrected, just to give it more contrast, I did not, however, sharpen the image.
Anyways, these are obviously poor tests but can serve as a bit of a guideline as to what to expect from these lenses. Another issue is the MD adapter, I’m not entirely sure that either adapter that I have access to is appropriate for these lenses. I’ll do more tests later.
Well, so far, so good. That’s all I can say at the moment. The rotary gage is operational, though it hasn’t had brushes made for it and it seems to output a reasonable amount of voltage difference based on displacement.
Here’s what it looks like so far:
The rotary strain sensor
I’ve put it through its paces thus far and I can see a 10mV difference when I move the sides, that’s good enough. Soon I’ll see if it works with the stuff attached.
After a few years of looking on the web for various items, the trend towards mandatory registration on certain websites is becoming more and more prevalent. Now, I’m not talking about social networking sites or the really massive corporations, I’m talking about the mid-size companies that have their IT dude make them a site.
Nowadays if you want to find any kind of information on the product a smaller company makes, you have to register for an account on their site even for things like datasheets. While on the surface this seems like a good idea, since you can engage the person in setting up an account on your site and have their e-mail address for later, it is irritating at best. Unfortunately, companies take it so far as to require you to register for almost every thing under the sun. Things I’ve seen required registration for:
Like I said, I can see the logic to it in terms of engaging the browser, however, myself I find myself backing out of the page, even if I need the information when presented with a ridiculous registration prompt. I’m fairly certain that other people do the same thing when looking for a product. Especially when looking for parts. There are so many manufacturers of similar parts and when you have to go from site to site and fill in a billion fields of data just to see what they fucking make is absolutely ridiculous!
All I can say is this. STOP REQUESTING REGISTRATION YOU IDIOTS!
In the end they only increase the traffic on their phone lines with engineers and designers that simply want some damned information. Stupid.
Now that It’s coming up on two years at the place I work, I was looking through some of the drawings. I figured it’d be fun to post some of them. I’ll simply place a gallery here, click the images to see a more detailed description
Note that these aren’t all of my drawings, but a decent selection of them.
This update is a little bigger than usual since I want keep the images and text as a sort of record of what I did for future reference. For the viscometer project, I’ve discovered that the motor is far too unreliable to produce reliable results despite algorithmic compensation. So now I’ve been charged with the task of creating a torque coupling that fits on to the rotating shaft. Now, there is no problem building the torque sensor, however, what is a problem is making it small and making it send the signal back to the device.
Also, instead of using an Analog Devices AD7705B 16 bit serial out ADC. Frankly, I’ve never used one but the greater resolution should enable more useful measurements.
Anyways, here’s a picture of the torque coupling before I ravaged it with hot glue.
Torque Coupling
It’s pretty fucking ugly but it’ll work for the time being. I did have the ribs that sit under the sensors quite a bit thicker, but there wasn’t enough strain to be useful for measurement, I had to hacksaw the chunks underneath right off.Unfortunately, I believe the polyurethane glue I used has caused strain on the sensor as it cured, I don’t know of it will go any further.
So, I’ve started on the circuit as of yesterday. I have it set up to take the PICKIT2 interface so that I can hot-program it and I setup the serial out board so that I can output debug data. This works thus far. Soon, I’ll be setting up the ADC and attempting to interface with it.
Starting on the ADC circuit
Here is an image dealing with the read/write cycle on the AD7705, also to note is that the AD7705 is MSB first.
The timing for read/write on the AD7705
Here’s the site they came from http://www.protongeeks.com/index.php?option=com_content&task=view&id=63&Itemid=27
Anyways, I’m glad to have my equipment back and ready for whatever crap I decide to build. Here’s a picture for posterity:
My bench as of Nov, 2008
Anyways, I’ll attempt to update this as much as possible, for whoever is interested (or not).
So now I have to find some way of measuring the torque applied between the two shafts of the viscometer. Here’s my idea.
Strain Coupling Model View
What you can’t see is that I plan to manufacture it out of plastic, that way the strain gage experiences the most out of the deflection of the part. I’ll use a flexible polyurethane bonding agent for the strain gages, allowing the forces of the strain to work without breaking the bond.
Here’s a through model view:
Strain Coupling Transparent View
Of course, it only took me a few minute to make this model but it helped me see if what I was doing would work, I also used FEA to see if the forces would be transmitted where I wanted them. The FEA results were promising, nice even strain along the gage surfaces. (Those gauge surfaces are seen in light blue). You can see though that the hole through the side relieves some strain on the strain area, though, this shouldn’t be an issue.
Strain Coupling Strain Test view
Here’s an image of the stress as calculated by Cosmos
Strain Coupling Stress Test view
Well, hopefully this will work. First I need to get the strain gages to provide reliable results. By using two of them, temperature concerns should no longer be an issue and should help mitigate innacuracies. I’ll post pictures of the finished part, though I don’t think I’ll do it on the NC, I’ll just do it manually, it may look like ass
Well, things are proceeding apace as far as the viscometer is concerned. Unfortunately, the motor is just too non-linear to serve as a useful measuring device. God I’m dumb!
Anyways, my graph-it program is working ok now and producing some useful graphs. I have programmed the save and load features and they seem to work just fine! It will eventually allow for a variety of data analysis techniques.
Here’s a picture of the linearity, or lack thereof.
Reciprocal of motor linearity
The blue at the bottom represents the overall error , the pinkish is the actual reciprocal of the tach values and the brown is the average of the tach values.
Hopefully I can get this working… Sigh!
Yes, I haven’t made a new youtube video in some time. Now the video I make is a redux of one I’ve made already, namely Doki Doki Panic. The reason I redid it was because the original wasn’t narrated. This one is, for only to add some personability and add some information to the video about Doki Doki Panic.
Now that I’ve got the new board working, I’ve been programming all of the pertinant functions back into the chip. This time I’ve redesigned them to be a little more modular and useful in the long term. As was mentioned in the post a while back, I made a new board and I’ve come to realise that the RS-485 Port is wrong. It has 2 connectors when it requires 3. A-B-Ground. Sigh!
Anyways, I’ve been running tests with the viscometer and everything is working great so far. I’ve got the temperature sensors working and the conditioning of them with OP-amps has worked like a charm. Though I find that the read value from the ADC is pretty jumpy.
Anyways, as reference, here some photos.
The Whole Deal
Temp Conditioner
Motor Linearity
Since I’m starting to take measurements based on time and value along with multiple data sets, I’ve decided that I need a new graphing program. This one will allow the use of multiple data sets and it will have save files to allow for easy recall of color settings and data parameters. Here are some of the features:
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This will all be written in FreeBASIC. Why? Because I like it. Also because FBEdit kicks ass in relation to FBIDE.
Anyways, I’ll post incremental versions.
Well, my design finally came to fruition from AP Circuits and I can say I’m quite pleased with the results. The overall appearance of it is really nice, for me at least.
Interestingly enough, I had some problems and made some mistakes. I ties the power regulator input into the motor – terminal… weird. Also, I didn’t tie AVdd high, or to anything.
Remember, programming a pic, remember these things
I kept ketting a “Error programming at address 0×000000″ error and it turned out to be the Avdd was disconnected.
Well, after spending a bit of time collecting prime lenses, I’ve decide to give them a brief review of sorts. The only way that can be objectively done is with a photographic test. Not being one for planning things out, I oped to use an old magazine and a couple of gameboy games as the test, this at least will be less a test of my focusing abilities and more a test of the clarity of the optics at a specified distance. So with no further ado, let’s introduce the lenses.
My Five Primes
All of these lenses were purchased off EBay. Some of them were cheap, the AF’s however were not so cheap. So, Let’s introduce each lens shall we?
Minolta 28mm F2.8 AF Lens:
This lens thus far has been a pretty good lens. It’s dead sharp and it’s nice and stout. It has a minimum F of 2.8 and maximum of 22.
And here are the shots taken from the lens. Keep in mind that these are directly from the camera and may look a tad dark. Click on the links to see the full size image, usually your browser will allow switching between sizes.
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Looking at the pictures, they’re pretty sharp. My own personal opinion is that there is some blurring around the text but color rendition is pretty good.
Minolta 50mm F1.7 AF Lens:
This lens is really nice for portraiture and it has nice bokeh. I find that on my camera, auto-focus tends to focus behind the subject at F1.7.
Here are the test images.
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On this lens it’s pretty obvious that at F8 it becomes pretty clear but at F1.7 and F22 there is some blur at the edges of the text. Again, the color rendition is pretty good and the clarity is a bit better than the 28mm AF lens. Something to take note of I guess.
Minolta 28mm F2.8 MD Lens
Something to note on all of these MD lenses is the fact that I used an adapter to facilitate mounting them on the camera. Something else to note is that they’re manual focus lenses and the focus is limited by my own vision, which is good, but not perfect. I tried to focus them via trial and error, however, I may not have gotten everything in focus at the lowest F number.
Here is the 28mm Minolta MD lens,. It feels really nice to focus and is of entirely metal build. It feels solid. Looking at it, it is almost entirely the same as the later model AF lens, certainly the majority of the design was retained for the later lens.
Here are the test images, remember, the color/focus may be different due to the adapter.
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Based on what I can see, there is little difference between the MD and the AF versions of the lenses. I suspect that my focus was folly in the F2.8 test, though I got it as close as I could over several exposures. There was slightly more chromatic aberration in the F22 test in the MD Lens as well. All in all, a comparitive lens if you like manual focus.
Minolta 50mm Rokkor F1.4 Lens
I have to say, I really like the look of this lens. The overall appearance of it looks as though it’s of high quality. Again, quality may be skewed due to the adapter. It’s also interesting to note that its maximum aperture is F16, lower than the other lenses.
Here are the test images.
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I have to say, with this lens at F1.4, everything seems washed out to a large degree however at F8 it appears as though it is somewhat sharper than its AF cousin despite the fact that the exposure is a tad darker. Even at F22 Vs. F16, the Rokkor appears a tad bit clearer, again, it could be the lower exposure time.
Star-D 135mm F2.8 Lens
I bought this lens because I wanted to try a manual focus lens and because it was cheap. Frankly, it’s a piece of shit. Taking a picture in any sort of light washed out the colors and any sort of night photography (with lights) results in halos and U.F.O like apparitions all through the image, though it does have the benefit of being fast. Though it is a prime lens that I own and as such, I figured it’d be worth testing.
Here are the test images.
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Clearly, this lens is inferior to the other lenses. While it is somewhat clear at F8, the contrast is lower than the other lenses. It’s not a bad lens of there is no other option but I’m going to try and find an AF verison.
Conclusion
Well, I can’t really draw too many conclusions from the images provided. I would need to take pictures in the real world and take images of more three dimensional objects in order to get a better idea of their true qualities. Truly, this is nothing more than a cursory test.
Please, if you have a comment to make, please do so
Also, here is the gallery of images used, for reference:
On Saturday Oct 25, 2008 (In Edmonton AB of course) there was some snow and record winds. I figure it’d be fun to post some pictures from that day as well as some of the damage from afterward. Click on the pictures to make them larger and see a description.
The Amp Hour Radio Show