beginner question

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professorx
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beginner question

Post by professorx » Wed Sep 10, 2008 2:31 am

hi, does anyone know of a kit that I could build, which would let me convert voltage into digital data I can read with usb? thanks!

Dean Huster
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Post by Dean Huster » Wed Sep 10, 2008 4:05 am

Gee. When I was a "beginner", I was fascinated when I could make a #47 lamp go on and off with an SPST slide switch when powered with a 6v lantern battery.

Dean
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

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Bob Scott
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Re: beginner question

Post by Bob Scott » Wed Sep 10, 2008 11:03 am

professorx wrote:hi, does anyone know of a kit that I could build, which would let me convert voltage into digital data I can read with usb? thanks!
You need an ADC with a USB port. Analog to digital converter with support circuitry. This is not for beginners to design because they need voltage references and possible analog voltage scaling and level shifting. You also have to know the maximum analog frequency and set the sampling rate at least 4X that. Then there's the USB part. You've passed beginner and intermediate and almost passed advanced. I know Nooothinnngggg about USB except that a USB host is way more complicated. It's a good thing you don't need to build a USB host.

Have you searched online electronics or hobby places for complete circuit blocks? How about hobby robotics sites?

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CeaSaR
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Post by CeaSaR » Wed Sep 10, 2008 3:08 pm

Gee. When I was a "beginner", I was fascinated when I could make a #47 lamp go on and off with an SPST slide switch when powered with a 6v lantern battery.
Gosh Dean, was that in the "dark ages"?

Sorry, I couldn't resist!!!! :grin:

CeaSaR
Hey, what do I know?

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MrAl
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Post by MrAl » Wed Sep 10, 2008 5:45 pm

Hi,

When i was maybe 5 i was fascinated that i could make the Christmas
Tree lights blink on and off, by simply plugging and unplugging them
in and out of the wall...until i got shocked and finger burned that is :smile:

When i was a little older i was also fascinated that i could make bulbs
inside model houses go on and off with switches, and that i could
control multiple bulbs with only one common wire and one wire for
each bulb.
LEDs vs Bulbs, LEDs are winning.

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philba
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Post by philba » Wed Sep 10, 2008 7:44 pm

This is not for beginners
That was then and this is now! yes, there is just such a kit - the UBW (USB Bit Whacker). It comes preprogrammed and you can either buy the kit or a fully assembled unit. $25. Look here - http://www.sparkfun.com/commerce/produc ... cts_id=762 or
here - http://www.sparkfun.com/commerce/produc ... ts_id=8265

Look for the ADC command to the UBW. You need to send it the ADC command and then read the result. Just hook up your signal to the right pin. No muss, no fuss.
By the way, the UBW is an amazing piece of work. Using a terminal like hyperterm, you can have it do all sorts of interesting things. Take a look here http://www.schmalzhaus.com/UBW/index.html Scan down to the documentation section at the end and read the firmware documentation.

Brian is working on a PIC32 version that will sell for a similar amount.

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jollyrgr
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Post by jollyrgr » Wed Sep 10, 2008 11:03 pm

MrAl wrote:
When i was maybe 5 i was fascinated that i could make the Christmas
Tree lights blink on and off, by simply plugging and unplugging them
in and out of the wall...
Ah, the joys of Christmas lights! I was about five when I learned to troubleshoot dead Christmas lights. Usually I would use a working set to test the "bad" bulbs of another string. I even made a tester using a lamp socket off a broken string and a 9V battery. I also learned that it was better to use a half dead 9V battery or I'd end up with more dead bulbs!
No trees were harmed in the creation of this message. But billions of electrons, photons, and electromagnetic waves were terribly inconvenienced!

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Sambuchi
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Post by Sambuchi » Wed Sep 10, 2008 11:50 pm

here is some constructive criticism. I agree with philba. I think what you want to do is quite doable. for a beginner it might be a little challenging. This would be a typical embedded project that would involve a microcontroller. I would purchase a demo board that had the following chip on it PIC18F4455 from microchip.

here is the demo
http://www.microchip.com/stellent/idcpl ... e=en021940

Its more than what you need but you will have everything!

Great learning tool.

Tony

professorx
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Post by professorx » Thu Sep 11, 2008 1:38 am

THANK YOU SO MUCH for all your help guys, that's awesome!

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Dave Dixon
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Post by Dave Dixon » Thu Sep 11, 2008 4:48 am

Making me think way back!!! I think I will start a thread entitled "first electronics project". Remind us what got us hooked in the first place.

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philba
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Post by philba » Thu Sep 11, 2008 11:54 am

Sambuchi wrote:here is some constructive criticism. I agree with philba. I think what you want to do is quite doable. for a beginner it might be a little challenging. This would be a typical embedded project that would involve a microcontroller. I would purchase a demo board that had the following chip on it PIC18F4455 from microchip.

here is the demo
http://www.microchip.com/stellent/idcpl ... e=en021940

Its more than what you need but you will have everything!

Great learning tool.

Tony
Actually, I said it is easy and then pointed him to a kit that will do exactly what he wanted.

I think in general we (yes, I'm including myself) tend to look at the complexity and ignore the simple (in this case premade) solution. The UBW is a perfect example of a building block that can be used by almost anyone.

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MrAl
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Post by MrAl » Thu Sep 11, 2008 2:39 pm

Hi again,


Hey i almost forgot that i have chips that read four channels at
once and send the data to the computer and i even have software
for it too. The four channels share a common ground.
I originally made these chips so that i could monitor batteries of
different sizes (NiMH, Li-ion, Lead Acid, etc.) while they charge
and discharge too and keep a log file of all the activity.
I got tired of using my ONE meter (which cost 100 bucks) to
monitor ONE battery at a time, so i needed something with
four channels. Also thought about building a stand alone
unit that has four channels and LED display. Many times i need
to monitor more than one thing at a time so i almost always
need two channels or more.
LEDs vs Bulbs, LEDs are winning.

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jwax
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Post by jwax » Thu Sep 11, 2008 6:24 pm

MrAl- Why don't you tell the professor how much you charge for your 4-channel ADC? That'll sell him one!
Hmm. Then there's the Serial-to-USB conversion, if the OP really needs USB.

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MrAl
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Post by MrAl » Thu Sep 11, 2008 7:22 pm

Hi John,


Oh yes i only charge $5 USD just to make up for the price i have to
pay out pretty much.
But yes John, as you said, this is an RS232 device and works directly
with RS232 so an RS232 to USB adapter would have to be used, and
they typically start at $15 USD.
Just to note, i tried it with the cheapest USB adapter i could find
and it worked well. I also tried it with a $20 USB adapter and that
worked too.

There are a few other components that have to go with it, such as
a few resistors, a small 0.1uf cap, and a regulator ic like 78L05 or
better yet LM317L, each only cost around 50 cents.

One additional note is that the grounds on each of the four channels
is shared between all four channels, meaning you can not measure
four totally independent voltage sources unless they can have their
grounds tied together with no problem.
If someone really needed to measure two separate sources whos
grounds can not be tied together they would have to use two chips
and two opto isolators (typically about 50 cents each too). This
setup would provide 8 channels, 4 in one set and 4 in the other,
and the two sets would be totally isolated from each other.
Of course that means two class 2 wall warts also (most are class 2
these days anyway) although they could be tiny ones.
LEDs vs Bulbs, LEDs are winning.

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