I fancy making a homemade one of these:

Ive ordered a couple of these thermocouples:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=280578252736&ssPageName=STRK:MEWNX:IT

which are rated:
Umax (V): 15.2V
I max (A): 9A

What kind of brushless RC motor would work best then? How are motor’s rated?

what about this?

Battery: 2Li-Po
Idle current: 1.2A
Load current: 14.7A
Power (Watt): 160watt
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=120472140154&ssPageName=STRK:MEWAX:IT

will the voltage be too high for the motor, Im assuming that 2x Li-po = 5.4v?

Im not expecting 15v out of the thermocouple….

I would imagine that motor is waaaaaayyyy overspecced!

I would see what power you can get out of the thermacouple first.

probably a good idea. will try and set up a test rig with a hot plate and a cold blowing hairdryer to get a c.60deg differential and see what I get out of it…

What should I look for in the motor spec then?

No idea, but I would expect the ones they use are 1-2W at most.
You will probably need a fairly low RPM too.

how are motors controlled? voltage?

I see I can get one of the ecofan replacement motors for £10 so might just use one of theirs?

The one in your picture is controlled mostly by magic. You’ll need a special controller for it to generate AC signals rather than just plugging a DC voltage in.
One of these
http://www.4-max.co.uk/esc.htm
Then you’ll need some more magic to make that bit of magic work 🙂
Lipo batteries look fun though.
http://www.youtube.com/watch?v=4OsBc8RqSKU

magic you say?

now Im really confused 🙁

Yeah I’d be inclined to get a conventional 2 wire DC motor.
However if you’ve got basic programming skills you could buy something like this http://www.coolcomponents.co.uk/catalog/product_info.php?cPath=50_74&products_id=583 that could be made to talk to the motor controller above by emulating RC servo signals.

Or buy one of these and a lathe for your shed:)
http://www.myersengines.com/engines/stove_fan_engine.htm

aha – I see, brushless, AC etc.

Right.

However if you’ve got basic programming skills you could by something like this http://www.coolcomponents.co.uk/catalog/product_info.php?cPath=50_74&products_id=583 that could be made to talk to the motor controller above by emulating RC servo signals.

ahhaahahha, ahahhahhaa.
Only if you can program it in Excel 🙂

right cheapo DC motor it is then.

He means it’s a clever motor that needs a computer to control it! You can’t just feed it DC straight off a battery. Looks like someting for a RC car really.

Anyway I would say buy the motor & fan blade from ecofan, it will probably be about right and save you from the R&D 🙂

That’d be good for cooling my toast in the morning.

http://shop.ebay.co.uk/?_from=R40&_trksid=p5197.m570.l1313&_nkw=dc+motor&_sacat=See-All-Categories

what RPM do you reckon? 200? 2000?

haha! How about this, hovercraft model fan 🙂

Type – GW/EDF64x6

Motor – EM150

Volts – 7.2 – 9.6v (11.1v can be used but will shorten motor life)

Amps – 4.4 – 8.3A

Thrust – 117 – 169g (201g @ 11.1v)

Weight – 69g

For testing i’d start with one of the very low power ones like this
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=280312836570

The ratings of
Umax (V): 15.2V
I max (A): 9A

For the heat pump will be the maximum you can put into it, rather than what you get out.
If you’re using it to generate electricity the figures will be a lot smaller – though I don’t know what magnitude, but I’d guess around 50-100
There’s some links off here to follow –
http://www.sparkfun.com/products/10080

If you are using a motor for a RC car/plane thing, then you will need a ESC (Electronic Speed Controller).

RC motors are rated in Turns, an 11 turn motor is more powerful than a 27 turn motor.

I would think you need to find out what voltage and current you are going to get first. Need to do this with a load on.

Once you know that and know how fast you need to turn the fan deciding on the motor RPM/V is the last thing needed.

You don’t need to shy away from brushless motors. The motor and controller for the power you are talking may well be cheaper than a DC one.

good point.

Which is more likely to be fixed/steady in output from the thermocouple A or V?

What does it do actually??

I always thought the Voltage was dependant on the temperature differential between the hot and cold sides. bigger differential bigger Voltage.

Its been a long time since I had to think about anything like this but I am also thinking the Current is going to vary with the amount of heat applied to the hot side.

Best just have a play around and see what you get out of them i think. Once you got some figures choosing a motor ought to be simple.

Is that a stove fan ?

They are only £80 to buy, probably spend that on messing about, unless thats what the desire is of course ?

Oh, and it’s geeks not nerds 🙂

They are only £80 to buy, probably spend that on messing about, unless thats what the desire is of course

well duuurrr 😉

cheers for the help guys.

I think my old mans got an old brass billet somewhere I can use as the conductive stand onto which I can attach the TEC. I can then thermopaste a modded heatsink on top of that with the fan in it/on it once Ive found out the output from the heat rig.

fun fun fun….

Did you ever get anywhere with this?

blimey.. retro thread!
But yeah, this is mine:
[video]http://www.youtube.com/watch?v=zsE4YtzXZe8[/video]

It works and it was fun to make, but its probably about 20% as effective as a bought model.

Cool. I quite fancy a go at making one – can you remember where you got the parts, and what motor you went for in the end?

Cheers

Tom

this motor from this supplier, but without the gear box
http://www.ebay.co.uk/itm/Gearbox-Kit-Solar-Motor-1-5-4-5-volt-10mA-v-DC-/300560347471?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item45facaf14f

2mm shaft prop like this (but mine was differnt ebay seller, no longer listing them)
http://www.ebay.co.uk/itm/234-4x-SF-Propellers-6045-Shaft-2mm-Suit-RC-E-P-/190524687042?pt=UK_ToysGames_RadioControlled_JN&hash=item2c5c2802c2#ht_1530wt_704

and I bought a pair of CPU heatsinks to sandwich the thermocouple between. Since the video Ive wrapped the bottom sink with foil.

Great stuff – thanks.

no worries. post the results here when youre done!

Will do. You said you’d bought a couple of the Peltier doofers – did you use them both in the fan, or just the one? I ordered one off ebay last night, then re-read this thread!

Only used one, but I wrecked the other I think when I tried to remove it from the sink having arctic glued it.

Oooh thats nice. Not seen the thread before. I’ve used a few on my old PC’s when going for Sub Zero CPU cooling.