How can you increase the current strength so that the nichrome thread heats up?

  • Apr 03, 2021
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I bring to your attention already 83 questions for the heading "question-answer". This question came from the reader Alexei with just such a title (I did not change it). If you have your own answer to the question, then write it in the comments below. I and other readers of my channel will be happy to read it.

The text of the question itself (literally) is as follows:

Hello, my old Soviet soldering iron burned out. There is a nichrome thread from electric kettles, tiles and I want to wind it again. There is a 12 volt power supply from an ultrasonic rodent repeller, but a small current strength (150mA). The nichrome thread does not heat up. How to increase the current strength or maybe you will advise something else. I want to say right away that I'm not good at electrical engineering.
The photo is illustrative.
The photo is illustrative.

After considering the issue, I consulted the reader within the framework of my knowledge and qualifications as follows:

To increase the current strength, it is enough to reduce the resistance of the circuit.

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Accordingly, if you want to increase the electric current flowing through the nichrome thread, you need either exclude additional resistors connected in series in the spiral circuit, or shorten the length spirals. The second option, although radical, is the simplest. However, this practical tip is not appropriate for every situation.

Nichrome wire has a certain cross section and can pass an electric current through itself only within certain limits. Otherwise, the wire will overheat and burn, and you certainly do not need such a result. The correspondence table of the wire cross-section and the permissible current value for it is given below:

To find out the amount of current flowing through the wire, you can set the multimeter to the ammeter position and connect the probes in series in the circuit, but be very careful not to get caught in the voltage. Another way is to measure the resistance of a piece of nichrome wire with a multimeter and calculate the current using the formula: I = U / R

where I is the current in amperes, U is the voltage applied to the wire in volts, R is the resistance of the wire in ohms.

In addition, I would like to draw your attention to the 12V power supply you are talking about.

The soldering iron works fine on 230V electrical circuits, why do you want to lower the voltage? If the power supply produces only 0.15A, then this value is enough only for a wire with a diameter of 0.1 mm, and then at the minimum temperature, for any other it will not be enough. Therefore, either take a more powerful power supply unit, or connect a nichrome thread from 230V.