Heating Element Experiment

Thread Starter

pradsy90

Joined Nov 4, 2013
3
I took a 120v TO 12v dc adaptor which gives 500 mA.

I cut the plug, split the wires (exposed copper) and connected them to two nails which have a heating element wire between them. The nails are 7 inches apart. The heating element wire was from a salvaged toaster. The wire won't heat up.

Any idea why? Is the current not enough?

Regards,
Pradhip. S
 

killivolt

Joined Jan 10, 2010
835
It may seem like a short and just pull the supply down at 500ma. Your connection could be poor. Connect directly to the copper wire and eliminate the nails. If you could measure the heat before and after you maybe heating but, there just isn't enough amperage.
 

tracecom

Joined Apr 16, 2010
3,944
To avoid overloading your power supply, you should limit the current to approximately one-half of its rated output. Thus, 500mA divided by 2 is 250mA. To allow 250mA to flow, given a 12V supply, your resistance element should be 48 ohms, which would yield 3 watts of heat. Granted, three watts is not a lot of heat, but if it's concentrated in a small piece of heating element, it could get hot enough to burn skin or to start a fire.

Be careful!
 

#12

Joined Nov 30, 2010
18,224
This is why $4 multimeters were invented. With no measurements about the actual resistance, temperature, current, voltage, or power, we have pretty much nothing to work with. Even decades of experience and a barrel of human compassion will only go so far.
 

Dr.killjoy

Joined Apr 28, 2013
1,196
I took a 120v TO 12v dc adaptor which gives 500 mA.

I cut the plug, split the wires (exposed copper) and connected them to two nails which have a heating element wire between them. The nails are 7 inches apart. The heating element wire was from a salvaged toaster. The wire won't heat up.

Any idea why? Is the current not enough?

Regards,
Pradhip. S
I would guess not enough current ...
Doesn't a toaster run off AC voltage???
 

killivolt

Joined Jan 10, 2010
835
The average toaster heating element is 70ohms. At 120vac and about 1.8amps once it reaches temp the resistance drops as the current follows approximately 1.5amps.
 

GetDeviceInfo

Joined Jun 7, 2009
2,192
I took a 120v TO 12v dc adaptor which gives 500 mA.

I cut the plug, split the wires (exposed copper) and connected them to two nails which have a heating element wire between them. The nails are 7 inches apart. The heating element wire was from a salvaged toaster. The wire won't heat up.

Any idea why? Is the current not enough?

Regards,
Prad hip. S
How Did you measure the temperature rise?
 
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