Give tension to a Nichrome Wire

Projects General Guidance
1

Hi,

I'm trying to heat a nichrome wire through a tension
generator of the tension of 12 V .
I want to control when the voltage is applied to the wire,
and in doing so I used a BC337 NPN transistor with base
voltage given by Arduino (5V, with a 1kOhm resistor).

The Nichrome wire has a resistance that increase with the heat,
at ambient temperature it is nearly a closed circuit with 0 impendance.

If I close the circuit with the 12V battery in series with the NPN and the Nichrome wire,
the transistor burns.

What should I do, in order to pilot the tension given to the nichrome wire without burning the NPN?

Thanks a lot

Riccardo

2

You will have to measure ( or calculate/look up) the resistance of your nichrome wire.

From that you can calulate the current it would draw.

Then you can choose a suitable switching device - eg power mosfet or relay

regards

Allan.

3

How much power do you want to apply to the wire?

Choose a power supply with the according (low) voltage, e.g. 2V, and a high current transistor (better: FET), and a heat sink...

4

DrDiettrich:
How much power do you want to apply to the wire?

Choose a power supply with the according (low) voltage, e.g. 2V, and a high current transistor (better: FET), and a heat sink...

I want to apply at least 12 V to the wire in order to heat it enough,
the resistance of the wire at ambient temperature is 4 Ohms, very low, I think this is causing all my problems

Thanks a lot for the answer!

5

I recommend using this site for a calculator. I did a project using nichrome and found I needed a lot of current to get the temperature i needed.
I ended up changing to using vape coils as I was lighting a fuse using a relay.

6

I want to apply at least 12 V to the wire in order to heat it enough,
the resistance of the wire at ambient temperature is 4 Ohms

Heat is related to power and 12V across 4 Ohms is 36 Watts. The current would be 3 Amps. Your power supply and transistor (or MOSFET, etc.,) would need to handle the current.

Some formulas for you -
Power (in Watts) = Voltage x Current
Power = V2/R
Power = I2 x R (where I is current in Amps)

And Ohm's Law: Current = Voltage/Resistance

7

Well if you have a resistance of 4 ohms and a supply of 12 volts . the current will be 12/4 = 3 amperes.

a mosfet such as an IRL1104 would handle this easily if +5v were applied to it's gate

regards

Allan.

8

A BC337 is woefully inadequate for the job of switching 3A, yes it will burn up.