Open Can with TEC (20' Match Light Video pg. 5)

[jayrob]

Re: Open Can with TEC

If I supply 6.28V to the circuit when driving a 16X DVD burner diode at 250mA (the sense resistor is set to 5 Ohms), about 2V is lost because of the regulator dropout, there is a 1.25V drop across the sense resistor, and let’s say the voltage drop of the LD at 250mA is 2.8V. So that’s 2+1.25+2.8=6.05V this time there’s only .23V for the LM317 to get rid of. But wait, when I applied the load to the battery the voltage began to drop. It seems that under load they can only provide 1.48V per cell. That’s only 5.92V, which means that the LM317, no matter how high it tried to raise the voltage, can only get the sense voltage up to 1.2V and at 1.2V the 5 Ohm sense resistor will pass only 240mA. Our regulator is now dropping out, and this was with fresh cells!  

I’m sure you can easily see now why when driving a red LD with a forward voltage drop of nearly 3V you must supply more than 6V to the circuit, and were you driving a Blurry LD which has a forward voltage drop of almost 5V, you must supply the circuit with at least 8V.

Now what would happen if I tried to attach a load to the circuit where the sense resistor had a range of 2 Ohms to 100 Ohms, was set to 2 Ohms, the circuit was supplied with 6V and the load was trying to take 5V? Well, that load sure wouldn’t see 5V, but it might see 3.5V, and with the LM317 doing all it could, it could probably only get the sense voltage up to about 0.31V. 0.31V divided by the 2 Ohm sense resistor (there’s Ohm’s Law again) would only give about 155mA. (Does that sound familiar?)  

I read this over carefully and I think I am starting to understand. Please give me some more direction here... I am trying to drive:
* 2 DDL circuits - 2 volts regulator drop out each? Plus 1.25 volts each - 6.5 volts??
* 1 open can LD - 3 volts? Gazoo, you are using this LD...can I figure 3 volts?
* 1 peltier - ?? Gazoo?? Same 12 volt peltier you gave me a link to from e-bay but I know it doesn't need 12 volts. Maybe 2 volts?
* 1 fan using a 5 volt regulator chip - 5 volts
All from 1 battery source. Maybe an 11.1 volt lipo pack? Or if you think I will need more voltage, the next step up for lipo is 14.8 volt.
Also, these lipo packs are made usually for a high current demand. Will a lipo fry everything, or will the circuits just take what they need?
Thanks for your guy's help,
Jay

 

[a_pyro_is]

Re: Open Can with TEC

I read this over carefully and I think I am starting to understand. Please give me some more direction here... I am trying to drive:
* 2 DDL circuits - 2 volts regulator drop out each? Plus 1.25 volts each - 6.5 volts??
* 1 open can LD - 3 volts? Gazoo, you are using this LD...can I figure 3 volts?
* 1 peltier - ?? Gazoo?? Same 12 volt peltier you gave me a link to from e-bay but I know it doesn't need 12 volts. Maybe 2 volts?
* 1 fan using a 5 volt regulator chip - 5 volts
All from 1 battery source. Maybe an 11.1 volt lypo pack? Or if you think I will need more voltage, the next step up for lypo is 14.8 volt.
Also, these lypo packs are made usually for a high current demand. Will a lypo fry everything, or will the circuits just take what they need?
Thanks for your guy's help,
Jay

A 7.4V pack should do just fine so long at the 5V regulator doesn't have a higher dropout (I'm assuming a 7805)
As for the two LM317 circuits, just add all the voltage drops for each circuit separately. Then take the higher one, that's how much voltage you'll need to supply. All three regulators will be running parallel, each taking only what it needs. I'm pretty sure the TEC will take less than 4V at the current you'll be running at, in which case, a 7.4V battery will be fine. And that way, you can pack more battery capacity into that thing. ;D

 

[jayrob]

Re: Open Can with TEC

Cool...I'll start experimenting with the 7.4 pack first then. Just waiting for the regulator chip for the fan. Yes, it is the 7805. I guess I can ignore the 3rd wire on the fan correct? And connect the 7805 the same as a pot? Supply wire to one pin and load wire across the other 2 pins?
Thanks Matt,
Jay

 

[a_pyro_is]

Re: Open Can with TEC

I don't know much about that fan, the third wire could be a speed control, speed or temp. sensor, or maybe for running at a different voltage. I just don't know... :-/
Have you tried running it off the 5V supply in your conputer?

 

[jayrob]

Re: Open Can with TEC

I don't know much about that fan, the third wire could be a speed control, speed or temp. sensor, or maybe for running at a different voltage. I just don't know...  :-/
Have you tried running it off the 5V supply in your conputer?

It's this fan here:
http://www.allelectronics.com/make-a-store/item/CF-250/40MM-5VDC-CENTRIFUGAL-BLOWER/-/1.html
Yes, I ran it off of just one 3 volt lithum using the black and red lead. So, I guess I don't need the 3rd wire. I won't need to build a circuit with the 7805 right? Just supply to one pin and load across the other two?
Jay

 

[Gazoo]

Re: Open Can with TEC

Correct, you do not need to add any additional components to the 7805...I think this is what you are asking.

As far as the third wire on the fan you don't need it.

 

[jayrob]

Re: Open Can with TEC

I just want to say that I am very thankful to everybody who has helped me with this project! I did some initial testing and so far, this thing totally exceeds my most optimistic expectations! I feel like I'm just breaking the surface here! Here are some initial current readings - 7.4 volt lipo supply:

LD - 2.98 volts @ 416mA (yes I can turn it way up with the driver - I did check this)
Peltier - 1.8 volts @ 422mA
Fan - 4.97 volts @ 192mA

I have only run it with these settings for 30 sec. to 1 minute max. initially and the block is cool to the touch!
First thing I did is light a match at 16'. Easily too! I have never been able to light a match at this distance before. I think I can go farther but that's all the room I have in my little test area.
Can't wait to get my meter from DDL's GB.
So awesome...Thanks especially to you Gazoo, and you too a_pyro_is. I have learned so much from this project!
Jay

 

[Gazoo]

Re: Open Can with TEC

Sounds awesome....16 feet ..You are going to have a ton of fun with it.

 

[roSSco]

Re: Open Can with TEC

That's very cool!

 

[Hemlock_Mike]

Re: Open Can with TEC

I can't hold anything steady enough for 16' match light ;D ;D
Good work.

Mike

 

[a_pyro_is]

Re: Open Can with TEC

That's great Jay!
Now how about some Pics/Vids? ;D

 

[jayrob]

Re: Open Can with TEC

That's great Jay!
Now how about some Pics/Vids?  ;D

Yes yes...pictures coming! I want to get it all buttoned up first though. These initial tests were done with wires and battery all hanging out...just to make sure everything was going to work. It's all going to fit nice and clean though. I set up the base pieces, (which hold not only the fan, but I'll have the switch and some wiring in there too) so that they can easily be removed if necessary using screws threaded up from the bottom. And the module is easily removable as well. I want to 'show off' some close ups of all my hard work after I get it all clean. But the way it is working with the drivers and the peltier with fan, etc...is so awesome! I really appreciate your guys' help...
Jay

 

[jayrob]

Re: Open Can with TEC

I can't hold anything steady enough for 16' match light  ;D  ;D
Good work.

Mike

I know what you mean Mike...But there is a wall that I could rest my hand on which is 16' away and the dot wasn't even focused as sharp as I know I could get it! It was an Ohio blue tip match. Not a strike anywhere match, but a blue tip. The black tipped Deal Extreme matches light easier than these. I use these for testing power and it lit in only 3 or 4 seconds at 16'! I couldn't believe it. I did it twice just to make sure...
Jay

 

[jayrob]

Re: Open Can with TEC

Coming along nicely. Some pictures...

Just a shot of the inner case wire routing and under side close up of the fan mounting - Going to be tight with 2 batteries, so the main wiring will be under the case...

I love the way the heat sinks that came with the peltiers seem to fit so perfectly for the base of this case! Besides the perfect fit for the fan/with regulator and small heatsink, they will house the switch and main wiring harness as well as a small lipo voltage alarm. They even hold the little fastening screws in place so that they won't fall out and get lost if I remove the base pieces from the case!

Almost done! Just waiting on the second battery, and the lipo alarm...
Jay

 

[a_pyro_is]

Re: Open Can with TEC

That's looking amazing Jay! I can't wait to see it in action!

 

[Gazoo]

Re: Open Can with TEC

I commend you on the lipo alarm...a great way to keep your batteries safe.

I am curious...how difficult was it to remove the peltier from the heatsink.

Also it looks like the heatsink you mounted the peltier to came from an older graphics card. I have one that looks exactly like it..