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.
Well, For the last week or so I’ve been developing a new viscometer board. Sloppy as it is, it’s a jump ahead from the last board in terms of overall inputs allowed. I used the 68PLCC package PIC18F6680 in this one because it had a sufficient number of IO and because it looks cool in it’s socket. 🙂
Anyways, this one has the following features:
- Several analog channels for temperature measurement.
- Several analog channels for use in a torque sensor set-up.
- Some analog channels.
- built in RS-232 Output.
- built in RS-485 Output.
- Provisions for PICKit2 hookup.
- TVS’s on all input lines
- Separate PIC12F683 for PWM output
- Debug Serial Output.
All in all, it’s gone smoothly, I’ve double checked a number of the traces, let’s hope all of them are well when they come back from AP Circuits later on. 🙂
What’s an abraser you ask? Well, it’s a device that has two abrasive wheels that are pressed against a plate with paint on it. The idea is to determine the wear a certain coating or paint will get with a number of revolutions on this device.
Anyways, it was acting up the other day and the guys at work asked me to fix it since the numbers were jumping into the thousands quite quickly. Since this device counted revolutions via an interrupted beam of light, I simply stated that it was dirty. I was right, it was just a bit dirty and after blowing the head out and looking at the signal, it was fine. What surprised me though was it’s electronic construction.
Surprisingly it was nothing more than a PIC-based protoboard with a transformer and a gearmotor, I was surprised that it was so sloppily put together. Here are some images of it in case anyone is interested or in case I wish to refer to them later.
As is evident, they used a PIC16C71 for their little project and soldered it together on a protoboard, very strange for company that’s been in business for so many years. They even used cables that didn’t have the correct number of wires in them, they simply trimmed the excess wire, sloppy!
I was perusing about today and found a helpful document about OP-Amps. It’s distributed by Texas Instruments and it looks really good even though I haven’t read it for the most part. You can get it here:
Or you can download from my site, just in case it got flushed down the digital void somehow.
Well, I’ve been thinking about deleting the gallery that’s been installed since I started this site. So far I haven’t even paid any attention to it since it recieves very little traffic and frankly, I don’t pay any attention to it.
I was thinking about deleting it… Instead, I’ve decided it’d be better to revive it, keep all the images that are on there and use it as a backup for all of my raw images. I’ll keep anything sacred close to the chest but other than that, I’m gonna make it public.
I’m going to start uploading sets of images, slowly but surely, as to avoid bandwidth charges!
Yesterday I started playing around with a solid state viscometer. This viscometer differs from other more physical methods in that it simply vibrates to determine viscosity. What I did was the following
- Cut a strip of aluminum sheet.
- Place a piezo tweeter element on each side
- Tried to solder the elements to aluminum
- Soldered two Teflon coated wires to the piezo material
- Took the whole thing and cast it into epoxy as to seal it and make it rigid between the tow piezo elements.
- Ground most of the excess epoxy off after curing.
- hooked a function generator, sine wave, to one side of the unit.
- Put the oscilloscope on the other side
- Found the most resonant frequency, which in air, is about 62.5Khz
- Tried ‘er out!
So far, it seems to provide useful results. I’ve tested it with water and oil. Oil tends to dampen the signal more than water which is a good sign since oil is more viscous but less dense, thus iy’s not functioning (entirely) as a densometer.
Here are the energy differences between water and air, the blue line is the sensor value.
Well, there we have it, a prototype vibratory viscometer. I guess the next step will be to do these three things.
- Produce a variable frequency.
- Amplify and use the signal appropriately.
- Produce a useful number.
Hopefully I’m up to the challenge. 🙂
Well, I took the plunge and built an RS232 output device so that I can track the values over a longer term than whatever my memory can hold. I’ve started with a series of tests designed to test the speed control or the encoder. So far my results have been poor. I’m not exactly sure why, perhaps the motor is hooped, maybe the encoder or perhaps even my logic with timing the pulses, I don’t know as yet. I’m going to purchase some different motors to try out.
Click on the pictures to enlarge them, there is a good description of each. There is also a zip file of the analysis data and the program so far.
For a while I’ve been looking for a decent freeware terminal program. Oddly enough, it’s been sitting right under my nose through a simple google search. I figure I’ll record it here for my own edification and file storage, just in case I can’t find it again… 🙂
Later tonight I’m going to try and post some of the results of the tests from the viscometer. So far, not so good. 🙁
So, I’ve been playing with simulating the output of the viscometer at a specified power output. When the real unit runs it seems to output noisy but patterned values. I’ve found that the output has a sinusoidal output with anomalies at the upper and lower value ranges. So, I’ve made a simulation of the outputs so I can find the best way to smooth out the sample sets.
In my simulation I generate 2000 samples and divide the samples into 10 sets. These sets are each 200 samples, the amount that’s being generated on the laboratory viscometer. The idea behind this is to make all of the value sets almost exactly the same, so far, I’m close with the average, but not close enough.Â Here’s a screenshot of the output
I’ll include a link to the file for shits and giggles (It’s freebasic BTW)
I purchased a lens off Ebay to test out. It was fairly cheap, like $25 all told and it looks great and feels great in the hands. I’ve taken a few test shots with the lens and I’ll post them here if anyone is interested in seeing what this older 3rd party lens is/was capable of.
Here’s the lens in question.
Here are some shots from the lens. I’m not going to edit them in any way. This is how they came off the camera. Sorry ’bout the extra shot of the lens, the gallery doesn’t allow removing images, weird.
So far it’s a really nice feeling lens. The aperature ring opens and closes smoothly and the focus bezel moves like a dream. It’s gonna take some getting used to, but I don’t mind manual focus too much.
Well, as far as viscometers go, I could be considered an expert by now (no, not really). Today my new board arrived and I assembled it, I’m kind of proud of it, it works real slick just like the last one. This one has the following changes
- ICSP provisions so that I can program it in place.
- a PIC18F2620. Has 10 times the program memory and RAM.
- diode protection in case the power is hooked up wrong.
- Fast recovery diode for motor induction absorption.
- Larger traces for the motor.
- Fixed resistor array.
Anyways, here is a comparison shot. Old on the left, new on the right.
Well there you have it!
I suppose I should post a picture of my new office. Despite the fact that nobody reads my blog, I’ll post a picture for posterity.
Pretty fucking messy, but that’s me!