Low Voltage Heating Element

[cks3976]

Hi,

I am looking to build a small heating element for an assay, which should be capable of heating a credit card sized Polypropylene / Glass cartridge to to around 120 degree F (50 Deg C) . I can either use a 9V or 12V source for this.

Please advice.

PS : I am exploring following options:
1. Peltier TEC
2. IR LED array, and
3. Positive PTC with Wire coil

 

[Pommie]

In the past I've used **broken link removed** resistors to do this. Easily controlled by a MOSFET.

Mike.
Edit, when you say 9V or 12V, you will need a substantial (5A) power supply for this - not a battery.

 

[rjenkinsgb]

The simplest thing for a fairly low temperature like would just be a few power resistors stuck or bolted to a piece of aluminium sheet.

As it happens, I have a virtually identical device in my "to do" list. These are the ones I got, a pack of five 33 Ohm 17 Watt power resistors:


They are each around 75mm long and 10mm wide.

On 12V, each resistor dissipates around 4.4W, so all together 22W if you used all five (around 2A at 12V). I was going to use four with a small gap in the centre and a temperature sensor, then PWM control, but if it's not to a few degrees you could use a simple mechanical thermostat.

[Pommie beat me to it with the same basic idea, while I was transferring the photo from my phone].

 

[ClydeCrashKop]

Light bulbs get hot without using much power.

 

[Pommie]

Light bulbs get hot without using much power.

They get hot because they use lots of power. Well actually the same amount of power as they produce heat - actually slightly less as some is visible light.

Mike.

 

[Nigel Goodwin]

Light bulbs get hot without using much power.

It's essentially just a resistor - with some (and not very much) of the heat wasted as light. A resistor will get hotter for the same amount of power, as you're not wasting any as light.

 

[gophert]

I would bolt one of these 30 ohm resistors

to the bottom of a 1/8" aluminum plate the size you need then insulate the resistor and the rest of the bottom of the plate. Then power with 12VDC. You'll get about 400mA and 5W. It will take a bit of time to stabilize. You should add a PWM controller to trim to the power needed to minimize overshoot when used with a thermostat. Add a thermostat and PID control logic with a temp sensor and it will be spot on.

the more logic you add, the greater current can be used to heat and keep the temperature in your desired zone.

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[cks3976]

Thank you all for your feedback. I think the resistor option seems best from both operation and cost point f view. I will try the same. Thanks again