Jump to content
43oh

Electricity monitor - need some help


Recommended Posts

Can anyone give me a bit of help with (outdoor) IR sensing?

 

My biggest project goal is a home energy usage monitoring/logging system. The meter on my house has an IR LED that flashes for every watt-hour, and I was going to use an IR photo-transistor to sense the flashes. Well, an IR photo-transistor works just fine to sense a VCR remote, but the flashes on the meter... outside... in the sun... are a bit too dim, comparatively.

 

The whole saga is here (with video): http://blog.docstech.net/2010/08/27/in-theory-it-was-perfect/

 

Any help would be greatly appreciated.

 

-Doc

Link to post
Share on other sites
  • Replies 78
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

@GeekDoc It does work on my board, I am using CCS. Must be debugger.

In IAR Embedded Workbench this code working too without any problems...

Copy Your code into an old, fully functioning project. You may have accidentally overwritten something in the default settings ...

Posted Images

Sure thing, but Paint? My OCD will not allow such haphazardness!

 

Using Visio (still have MSDN subscription from work!):

IRsensor.jpg

(Added to my blog; we non-admins don't have the option to upload files.)

 

This works fine on my workbench with a VCR remote.

 

One thought: I think my pull-up resistor is a little higher value than it needs to be (I just grabbed one that worked on the bench). Could that decrease sensitivity?

 

-Doc

Link to post
Share on other sites

@Sean:

 

I actually had about a 2" square of duct tape holding the sensor to the plastic "shell" of the meter. The little plastic "light-pipe" is about 3-5mm from the inside of the "shell". If I could get inside the plastic cover, I think I could make it work; but the power company would frown on that. :D

 

-Doc

Link to post
Share on other sites

There must not be enough light falling on the sensor for it to switch on and pull the pin low. I would try something in the range of 4.7K to 10k.

You can check voltage with a multimeter. Do you have one?

 

Added to my blog; we non-admins don't have the option to upload files.)

The upload attachment is to the right of the options tab.

Link to post
Share on other sites
There must not be enough light falling on the sensor for it to switch on and pull the pin low.

That's what I figured.

I would try something in the range of 4.7K to 10k.

Might that help? Do transistors switch in a continuum, or strictly binary?

You can check voltage with a multimeter. Do you have one?

I actually have a couple of decent DMMs (and a nice Weller soldering station that is wasted on my meager skills). The problem is that the flash is too fast to register. That's where an o-scope or at least a logic analyser would come in handy. Might have to wait until NJC leads us along to the end of his ambitious project...

 

-Doc

Link to post
Share on other sites

I just ordered some BPV22F photodiodes from eBay. Datasheet: http://www.datasheetcatalog.org/datasheet/vishay/81508.pdf

Supposed to be:

...high speed and high sensitive (sic)... In comparison with flat packages the spherical lens package achieves a sensitivity improvement of 80%.

...and probably better than the part I salvaged out of an old mouse!

 

-Doc

Link to post
Share on other sites

if your still having issues with your analog IR detection, I have an extra light to frequency converter from parallax if you would like

its free** if your interested in one, I picked them up on clearance at radio shack not too long ago and i dont think i will ever use all 4 lol.

 

 

**free - means I will pay for shipping if its within reason

Link to post
Share on other sites

Doc,

 

I saw your post before I checked the forums today, so I responded on your post directly. I'll try to provide a slightly more thorough answer here since I have room to ramble.

 

You asked in one of your posts here if transistors are strictly binary. Far from it, transistors are an analog mess; transistors form not only the basics of digital circuitry (such as making AND gates, OR gates, Fip-Flops and other things), but also form the basis of amplifiers. Transistors are quite a pain to get working effectively at high speeds because they are analog in nature. There are different regions of operation based on the voltages applied to them for each type of transistor. There are also two major types of transistors, MOSFETs, and BJTs. This might be more information than you want though. If you are interested, start looking at "current

Link to post
Share on other sites

@NJC:

 

Wow! Thanks for the education! This opens up lots more possibilities. Now I have hope.

 

I'm going to try lowering the pull-up resistor value first (to keep it simple), then I may dive into learning about a comparator. I understand the concept, but I've never used one. I love learning new concepts!

 

-Doc

Link to post
Share on other sites

Minor update:

 

I swapped the 47K pull-up for a 10K, and the salvaged mouse photo-trans. detected a VCR remote from about four times the distance (~12" vs. ~3").

 

I took my test setup outside, and the darn thing worked on the meter! I'm trying not to get my hopes up, as it is raining at the moment, so I didn't have the sun to compete with.

 

Next steps: Try it in the sun, and try it with about 20 feet of wire to make sure I can run the sensor wire into my basement, where I plan to have the monitor.

 

if your still having issues with your analog IR detection, I have an extra light to frequency converter from parallax if you would like

Very generous of you @jsolarski. I'm going to keep trying the photo-transistors for a bit before I try to learn another piece of hardware (that sounds pretty complex!). I'll let you know when I've given up on the concept. ;)

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...