looking for tiny heating plate

[givingtnt]

so, im looking to get a tiny 12v heating plate. something to heatup water to around 91-96 ^oc

I was looking at peltier modules, but no one seems to really know what kind of heating temp I can get with that. 

 

is there anything else I can  find thats cheap, and relativly small ? (max of 12x6x1cm)

[Speakerator]

to be fair, I'm no electrical engineer - but if I remember correctly a kitchen stove (running of 230V in Europe) pulls a massive current from the wall to acquire the energy neccessary to boil water. With only ~5% of the voltage... not goint to happen^^ If you plan on trying to keep your coffee hot (which is way below 96°C) - there are plenty of gadgets out there for that purpose

[givingtnt]

17 minutes ago, Speakerator said:

to be fair, I'm no electrical engineer - but if I remember correctly a kitchen stove (running of 230V in Europe) pulls a massive current from the wall to acquire the energy neccessary to boil water. With only ~5% of the voltage... not goint to happen^^ If you plan on trying to keep your coffee hot (which is way below 96°C) - there are plenty of gadgets out there for that purpose

no, im looking to MAKE coffee

im looking for a way to make things heat up to around 90^oc.

 

could I just power an old cpu with a molex connector ?

[WkdPaul]

it's not really possible unless you're ready to wait for hours ...

 

This explains how long a 1500w kettle take to boil 1L of water;

http://home-flowers-plants-garden.blogspot.com/2015/03/how-long-to-boil-1-liter-of-water-in.html

 

So basically, using a 100w heating element, boiling 1L will take 1 hour (from 15°C), or 9 minutes for 1 cup of water ... throwing more Watt at it will make the water boil faster.

 

A Peltier plate could do it but it's not made for that. And I'm not sure where you could find 12v heating elements. Maybe RV or camping accessories???

[Speakerator]

1 minute ago, givingtnt said:

no, im looking to MAKE coffee

im looking for a way to make things heat up to around 90^oc.

 

could I just power an old cpu with a molex connector ?

erm.no^^ Though I think I remember watching a youtube video a long time ago, where they soldererd wires to CPU pins and got it to kick out massive amounts of heat. 

[givingtnt]

1 minute ago, wkdpaul said:

it's not really possible unless you're ready to wait for hours ...

 

This explains how long a 1500w kettle take to boil 1L of water;

http://home-flowers-plants-garden.blogspot.com/2015/03/how-long-to-boil-1-liter-of-water-in.html

 

So basically, using a 100w heating element, boiling 1L will take 1 hour (from 15°C), or 9 minutes for 1 cup of water ... throwing more Watt at it will make the water boil faster.

 

A Peltier plate could do it but it's not made for that. And I'm not sure where you could find 12v heating elements. Maybe RV or camping accessories???

well im looking up to heat a quarter (250ml) of water. and time doesn'T really matter, as long as it doesn'T take 10 minutes. though even then, for what im doing its not that bad...

[givingtnt]

Just now, Speakerator said:

erm.no^^ Though I think I remember watching a youtube video a long time ago, where they soldererd wires to CPU pins and got it to kick out massive amounts of heat. 

well, my q6600 at iddle is at 83 degrees

anyways. its a bit sad then.

though iv seen some of those silicon rubber heating plates... though they are a bit pricy...

[Bhav]

Technology seems to be advancing at a snails pace if people havnt yet started using GTX 480s for all their cooking needs.

 

 

[SLAYR]

10 minutes ago, Speakerator said:

erm.no^^ Though I think I remember watching a youtube video a long time ago, where they soldererd wires to CPU pins and got it to kick out massive amounts of heat. 

Fx 9590?

[Bhav]

5 minutes ago, SLAYR said:

Fx 9590?

With quad SLI thermis for pentuple the grilling power!

[Hackentosher]

You can get a few TECs and then sitch them together for a larger area, or get a prusa pcb heat bed. 

[Speakerator]

Found it (or at least something similar^^)

 

 

[givingtnt]

2 hours ago, Bhav said:

Technology seems to be advancing at a snails pace if people havnt yet started using GTX 480s for all their cooking needs.

 

 

 

2 hours ago, Hackentosher said:

You can get a few TECs and then sitch them together for a larger area, or get a prusa pcb heat bed. 

 

1 hour ago, Speakerator said:

Found it (or at least something similar^^)

 

 

 

 

welp, too late, I just bought a cheap, tiny panini maker (max 375°f). and my container : glass Tupperware (max reccomended heat res : 400°f)

[mariushm]

No, you simply can't heat even a cup of water in reasonable amount of time, without using a lot of power.

 

Your best bet would probably be to have the water in a metal cup (copper or something) and have the heating elements soldered or pressure mounted directly on the bottom of the cup. The only better way would be to have the heating element directly floating in the water.

 

Easiest "heating elements" would be plain resistors. You have the basic formulas  V = I x R from which you can derive P = I x I x R which is the power dissipated in a resistor.

There are TO-220 or TO-247 or similar packages resistors with low resistance values, here's for example a 2.7 ohm 100w max resistor : http://www.digikey.com/product-detail/en/ohmite/AP101-2R7-J/AP101-2R7-J-ND/5878477

 

So you have a 10 ohm resistor, which means since V = I x R then the current through the resistor would be V / R = 12v / 2.7 ohm = 4.44 ohm , so the power dissipated in the resistor is  P = IxIxR = 4.44 x 4.44 x 2.7 = 53 watts , which is a reasonable value as long as the resistor is constantly heatsinked.

 

Basically, if you have a 12v power supply capable of 5A or thereabouts you could use some lead free solder to solder AWG18 wires to the resistor, put some heatshrink over the leads to make it look nice, put the resistor in the coffee cup full with water and heat your cup with 50 watts of energy. The resistor lasts for up to 175c and the water temperature will keep rising and rising until it will no longer act as a heatsink for the resistor.  You can solve the problem of overheating by adding a NTC or PTC (a resistor that changes value with temperature) and if you want to make it completely analogic make a circuit that when the NTC/PTC resistance goes up or down a certain amount, a transistor or mosfet is turned on or off , to disconnect the resistor and therefore no longer heating up.

 

There are other resistor values on that site (or any reputable store of electronic components) so you can pick the best resistor value for your voltage . There's also resistors with lower maximum power (like 35w for example) but keep in mind it's not a great idea to go over 60-75% of the rated power of the device.

Also keep in mind that with DC voltage if you put the heating element directly in the water, you have to consider the possibility of electrolysis so often some direct heating solutions reverse the polarity every few tens or hundreds of milliseconds.

 

If you still aren't aware of how much water can cool down, here's a 24v 40 A power supply being tested with a bucket of water .. it takes minutes for the water to heat enough to no longer heatsink the wire shorting the power supply :