Instructables

looking for well controlled heating element.

I have a few small projects in mind that have come to a standstill because I lack one piece.  What I would like to get my hands on are small heating elements capable of temps between 80-400 degrees F that are as accurate as possible, preferably within two degrees.

I have tried researching this online, but after browsing for an hour I was unable to come up with anything that would suit my needs.  I have considered buying a digital heat gun, but I can't find reliable info on how accurate they are and what range they have.

I don't want anyone to think I am trying to build bombs or anything like that so here are two of the applications I had in mind.

The first is my truck.  From what I understand those 'super chips' people buy to override the computer and add power typically change the air/fuel ratio.  That can be done by manipulating the perceived temperature of the air entering the intake.  My idea is to create a small housing around the airbox thermostat and digitally manipulate the termp in order to manipulate the A/F ratio. 

My second idea is...well...best not discussed openly, but I assure you it has nothing to do with the creation of weapons of any kind.

Any thoughts?


samaddon1 year ago
you can use graphite its a semi conductor if you will supply it 9 volts it will get hot upto 200 degrees C it is so hot and it is very compact. you can see my project here:
http://www.instructables.com/id/How-to-make-a-soldering-iron-with-a-6-volts-batter/?ALLSTEPS
samaddon1 year ago
you can use graphite its a semi conductor if you will supply it 9 volts it will get hot upto 200 degrees C it is so hot and it is very compact. you can see my project here:
http://www.instructables.com/id/How-to-make-a-soldering-iron-with-a-6-volts-batter/?ALLSTEPS
chilidawg1 year ago
I know this is an old post but I just came across it.
A Peltier junction would be perfect for this. You can control it precisely, use the same device to measure the applied temperature, and you can either heat or cool depending on your needs.
EvilBeagle4 years ago

I believe I can guess at option #2..  think about these components for a while.

A soldering iron (not gun) with a removable tip (remove it)
A sliding lamp dimmer, spliced into the soldering iron cord
A brass screw that threads into the iron a brass pipe cap (with a hole for the screw drilled in the bottom)

As far as determining temperature, I imagine you could play with the slider and an IR grill thermometer , marking specific temps on the dimmer.(no guess as to how accurate you'd be able to get) Hoping you have volcanic luck.
So, you're looking to build bombs, eh?
;-)

I mean you want a "heating element" of some kind?  You sound like you might be new to this concept of heat, and how it works. 

I mean a the filament of a (incandescent) flashlight bulb is a "capable of temps between 80-400 degrees F", and assuming all you wanted  to heat was the filament itself.  There might even be a way of controlling its temperature to within 2 F degrees.

What I am saying is this:  in order to heat (or cool)  some thing to a particular temperature, it is important to examine the thing being heated (or cooled).

As an analogy, consider a tank of water that leaks, badly, situated on the shore of shore of a vast reservoir of water.  (A picture of this is attached.) To fill the tank, you pump water into it, using a pump.  If you can manage to pump water into the tank at the same rate that it leaks out, then the water level in the tank will remain constant.

The problem of heating some thing is similar.  Your heating element is like a pump.  You use it to put heat into the thing you are heating.  But the heat leaks away to the cooler surroundings, like the water in the tank leaks away to back to the reservoir.  The thing you are heating, a room, or the interior of an oven, for example, is like the water tank.  The problem of controlling the temperature of the thing is similar too.  If you can put heat into the thing, via the heating element, at the same rate that heat is leaking out to the cool surroundings, then the temperature will remain constant.

The usual trick for maintaining the temperature of some thing at a constant level, is to use feedback.  You have a temperature sensor, and you watch it.  If the temperature gets too low, you increase the rate at which you're supplying heat. Similarly, if the temperature gets too high, you reduce the rate at which you're supplying heat.  Well actually, you don't do all the monitoring and adjusting yourself.  This is the job of a control system.  Specifically a control system for regulating temperature is called a thermostat.

Anyway, back to the subject of you and your desire to heat the air going into the intake manifold of your truck,  the first thing you should do is calculate/estimate the amount of heat flow you're going to need to heat this air.  Multiply the desired temperature increase, times the specific heat of air, times the flow rate, and you should get an answer in units of power, joules per second, or equivalently, watts.  Assuming you are using an electric heating element to supply this heat flow, then this answer tells you approximately how big (in terms of power) of a heating element you need, and how much electricity you need also.




leaking-water-tank.png