Can a Propeller be made into a Dual Channel Function Generator? If so, I need one...
Digitellum
Posts: 5
As the title suggests I am in need of a replacement instrument for
my recently departed Wavetek 146 unit. I bought that gizmo on Ebay
several years ago and ended up having to repair the power supply
before I could use it. Another classic Ebay purchase.
Now I have a different problem in that it's croaked and I can't see well
enough to repair it without doing more damage to it than good or
for that matter build anything tiny anymore.
So here's the extended question to all who hack up hardware and
software for propellers.
I would like to have a propeller based instrument to continue my
goofing around with bubbles entrained in a fluid of low viscosity.
Sort of bubble wrangling if you will.
Further, I would like to use all sorts of transducers and emitters from voice coil
driven diaphragms of large diameter to Piezoelectric Transducers, and now I
would really like to experiment with this approach (see link below).
http://zao.jp/radio/parametric/index_e.php
So there you have it, I desire a custom wacked together stand alone
instrument that can output 2 different waveforms simultaneously from
.1 Hz to 100Khz both sine and square into 50 Ohms at 20 volts P-P.
It would need to have an enclosure and readout large enough to see
what the waveform selected is, the frequency, and the level at a minimum.
A sizable multifunction rotary control would be nice instead of momentary
switches for everything. And whatever software functionality could be brought
bear without this becoming one's life's work. ie. sweeping, tracking channel
to channel, stored setups, auxillary composite video output, remote control
over usb, sound file playback and recording.
You get the picture...
This propeller chip looks like it could potentially do this job but I just don't
have the expertise to really know for sure and reading this forum makes that
determination as clear as mud.
BTW: I am well aware that I have many instrument shopping choices. I can get something
from China or I can get something from China via Korea that I'm sure would do a fine job of
replacing my Wavetek.
But that's not the point is it?
Also the self contained form factor is very important as the laptop is already busy.
If this is a rational endeavor I do have a small budget to replace my existing junk
and would be glad to hear what doing something like this might cost?
Please advise...
Cheer's
Staff Member
:cool:
my recently departed Wavetek 146 unit. I bought that gizmo on Ebay
several years ago and ended up having to repair the power supply
before I could use it. Another classic Ebay purchase.
Now I have a different problem in that it's croaked and I can't see well
enough to repair it without doing more damage to it than good or
for that matter build anything tiny anymore.
So here's the extended question to all who hack up hardware and
software for propellers.
I would like to have a propeller based instrument to continue my
goofing around with bubbles entrained in a fluid of low viscosity.
Sort of bubble wrangling if you will.
Further, I would like to use all sorts of transducers and emitters from voice coil
driven diaphragms of large diameter to Piezoelectric Transducers, and now I
would really like to experiment with this approach (see link below).
http://zao.jp/radio/parametric/index_e.php
So there you have it, I desire a custom wacked together stand alone
instrument that can output 2 different waveforms simultaneously from
.1 Hz to 100Khz both sine and square into 50 Ohms at 20 volts P-P.
It would need to have an enclosure and readout large enough to see
what the waveform selected is, the frequency, and the level at a minimum.
A sizable multifunction rotary control would be nice instead of momentary
switches for everything. And whatever software functionality could be brought
bear without this becoming one's life's work. ie. sweeping, tracking channel
to channel, stored setups, auxillary composite video output, remote control
over usb, sound file playback and recording.
You get the picture...
This propeller chip looks like it could potentially do this job but I just don't
have the expertise to really know for sure and reading this forum makes that
determination as clear as mud.
BTW: I am well aware that I have many instrument shopping choices. I can get something
from China or I can get something from China via Korea that I'm sure would do a fine job of
replacing my Wavetek.
But that's not the point is it?
Also the self contained form factor is very important as the laptop is already busy.
If this is a rational endeavor I do have a small budget to replace my existing junk
and would be glad to hear what doing something like this might cost?
Please advise...
Cheer's
Staff Member
:cool:
Comments
Yes, I'm guessing you could pull this off with the Propeller chip without too many dramas.
What are you doing with piezos and bubbles? sonofusion?
The specialist here is Phil so I will wait for him to chime in. Andy also has done work with generating all sorts of waveforms so he may be able to guide you also. Unfortunately, this is not my area of expertise.
Cheers, Ian
Can you post any results or information on your test set-up? This is very intersting.
How low viscosity are the fluids?
I have to be a bit guarded with respect
to divulging any details that might get me in
trouble with the folks that I work with.
It is nominally 1.1-1.6 cP and can increase to
60.1 cP under very unusual circumstances.
The most telling property is that it's
really yucky to get any of it on you...
Especially if it's NOT yours.
Interesting?
And How...
What the stuff is?
Not so much.
How to get the bubbles to dance given
the environment?
For sure.
Maybe the most useful information I can impart is as follows;
No direct contact with the mystery fluid ever.
No making smaller bubbles out of larger ones.
Make all bubbles gather in one spot within a tiny 3D space.
Contamination of the fluid itself or environment is very bad.
The big "G" is of no concern.
Now I have a question for you Professor if
you would indulge me.
Are you really David McCallum?
Digitellum
I wish it were sonofusion at this point.
I am attempting to partially sonicate
a fluid so that the gases form into
bubbles which can then be sonically
driven to a fixed location.
I know this sounds kinda dopey.
The conditions under which this must
be accomplished are the real challenge.
Hmmm.
Here's the point to consider.
How would one couple intense sonic power into
a fluid if one can not interface directly
with it and further, the operating environment
prohibits using any sort of "Bath" or known
couplant materials?
No fluids, gels, etc.
No mechanical moving parts such as a shaker,
whistle pump, spinning gizmos or anything using
substantive amounts of kinetic energy.
If you've got any ideas at all please let me know.
Thanks for your time and attention.
All the best!
Digitellum
I don't know if this is how you're supposed to add material to a thread?
So if it's not, then please advise.
I had been really ill over the last few weeks and unable to mess around
with much at all.
Although the dark circles around my eyeballs are looking much better thank you.
Now as to this function generator project.
I need this built real soon now.
Here's some example devices that I had been looking at on the web.
None of it really works out for me.
Whomever might want to have a look at this nonsense.
The following unit is functionally great but would need the additional
high power and high voltage outputs and a much bigger display.
I've fondled this in person. Very tiny buttons, and really small legends to read.
Not good.
Look here at the Rigol 1022 Arb.
http://cgi.ebay.com/RIGOL-DG1022-FUNCTION-ARBITRARY-WAVEFORM-GENERATOR-20M-/260623159235?pt=BI_Signal_Sources&hash=i
tem3cae59cfc3
Here are some inexpensive gizmos that sorta kinda have whats called for:
http://www.elv-downloads.de/downloads/journal/dds10_110.pdf
http://www.elv.de/output/controller.aspx?cid=74&detail=10&detail2=28511
http://www.elv.de/output/controller.aspx?cid=74&detail=10&detail2=7043
http://www.gabotronics.com/development-boards/avr-xmegalab.htm
http://www.bartek.com/DDS15XF.htm
http://www.newark.com/aim-tti-instruments/wa301/function-generator-signal-amp-freq/dp/71C2635
As an aside, believe it or don't
The link below is a little unit that is very close to what's needed sans the two channel
requirement and non standard power outputs.
Of course it's got buttons, knobs and blinky lights where a single decent quality rotary
encoder, and say an x/y joystick could step through the onscreen menu for control
purposes but it does have a pretty sizable display!
Gander the SMT unit.
http://cgi.ebay.com/10MHz-Function-Generator-Waveform-Display-EM1656-/370472909459?pt=BI_Signal_Sources&hash=item564
1e7fa93
If you look over these examples you will see pretty nice packaging in the
ELV 8010 kit and what appears to be a very fine value overall but it's not
dual channel and if you wanted to buy two of them, they couldn't be synced,
nor do they talk to each other or anybody else for that matter. Hmmm.
This device has a good stout output but would still need a wideband output
amplifier and high voltage add-on anyway.
There's an example of a TTI Function Generator Amp unit in the Pile 'O' Links
somewhere that will do the trick but it would be better if the amp where in
the same box as the generator.
On almost all of these units you can't save any setups nor can you program
sequential timed steps or preload a prompted experiment so that someone
less experienced can reproduce it, shoot they can't even be
controlled over Ethernet.
What's up with that?
Also if my instrument were made up of lots of well glued together standard
parts from Parallax including the box cool! I'm down with that.
In reality what I need is a standalone PropScope that has two output channels.
If that can be cobbled up so be it.
If the basic stuff works and more advanced features can be added over
time that's not so bad either.
You get the picture.
If any of you Propeller folks are nuts enough to entertain fashioning
some sort of test gizmo that could do the job let me know via email
with your contact info.
I'll be getting back to you right away.
Once again thank you for your interest.
All the best,
Digitellum
:cool:
Can you clarify what you mean by sonicate? Usually I hear that term in reference to trying to tear apart biological cells.
The sound energy that creates gases could be different from the sound energy used to wrangle the bubbles around, is that true? Or is it necessary for the same sound source(s) to do both?
You can create bubbles by rapid decompression, or even by cavitating the fluid by running it quickly through a tiny orifice, but if this fluid contains mammal cells, for example, then such procedures are in danger of ripping those cells apart.
If you use an ultrasonic transducer, can it be in touch with your mystery fluid? Can you use some sort of stainless steel "membrane" to allow sound to travel from transducer to fluid?
Ok, All really good questions.
I am using the term sonicate as shorthand for applying
ultrasonic energy to a material (in this case a fluid)
at sufficient power density to accelerate the dissolution
of various gas molecules present in the mystery fluid.
Sonication in the biological sense generally indicates cellular
wall or membrane disruption which is usefull for the separation
of the cell's internal molecular contents which are not normally
excreted by the cell when intact. Useful in studying the stuff
inside, and for culturing purposes.
In this case the volume is very small roughly 5mL confined to
a chamber that is 43.65 mm long by 10.35 mm wide on all
4 sides.
The chamber wall is 1mm thick and is sealed with a cap.
Coupling losses at 22.5 Khz are very roughly -.18dB.
Nothing can contaminate the fluid so any direct contact is
out of the question.
You have noticed something that most folks miss!
Because you appear to get the picture then it would become
obvious as to why I woud need a multi-channel generator.
Shoot, 2 channels is the minimum 8 would be much better.
Sonicate and Levitate would be the basics of what's called
for here. Although that does presume the influence of "G".
On the bench yes. In the end no.
More will be learned as we bumble along.
I might need to use transmitters on each of the long surfaces
and one at the non-capped end to pulse the bubbles in a specfic
direction of travel once they form.
Many times this can be accomplished with a swept signal.
Also might need to combine two waveforms together driving
a single transmitter element while pulsing the other transmitters
simultaneously or in a fairly precisely timed sequence.
But that's a bit further down the road. Just getting enough
power into the mystery fluid will be trouble enough, at this
point. Starting with a good basic processor controlled
waveform generator is what is needed first and foremost.
If you've been reading up on this stuff, you have probably
also concluded that coupling is the most fundamental problem
to solve.
New types of transducers made from materials other than
ceramics need to be tested. Some have very different driving
requirements. Hence the need for all sorts of signal outputs
and voltages.
Sorry to cut this short as I've been awake far too long.
I've got to go pass out for a while...
Will report back a bit later.
Keep thinking!
Digitellum
I'm showing my ignorance here. What do you mean by "G"? Is this something like a Q factor for ultrasound?
No details beyond the task at hand are necessary. "cP" is then dynamic viscosity? http://en.wikipedia.org/wiki/Poise
Can the container have a filament, ball or other component? I would suggest something along the lines of adding a ball bearing and making it vibrate magnetically, if such a magnetic accuator could be coated so as not to be considered "contamination". Can a piezo crystal be present as part of the container? Can the container be a flexible bag? Can the container be made of piezo material, and the entire container be the transducer? The TRIZ class I took suggested that one should identify the contradictions, then remove them, and the the problem can be solved. But I don't know if there is enough information to be helpful.
No I am not David McCallum, only a simple gardener.