On the basis of a powerful IRF3205 field-effect transistor, you can assemble an original soldering iron with which you can solder, and this will be a touch soldering iron, you can turn it on and off by touching a finger or pressing a button, as well as adjust the heating temperature.The heating element is the transistor itself, or rather the transistor crystal, the heat from which is transferred to the flange and the flange serves as a sting.
Let’s first see how it works.A field-effect transistor has a drain-source channel, which can be represented as a resistance or a resistor that has different resistance depending on the gate charge.If you apply a voltage of about 10 Volts to the gate, then the IRF3205 transistor will open completely and the resistance of the drain-source channel will be about 8 mOhm.But if the gate is not fully charged, but let’s say 5 Volts, then the channel resistance will be greater and this conditional semiconductor resistor will get very hot.
Connect a 12 volt incandescent lamp to the transistor drain.With a power supply of 10 Volts and without a charged shutter, the lamp will not shine.Now touch the shutter-drain of the transistor with your finger and the transistor will open and the lamp will shine.The more voltage you charge the shutter, the brighter the lamp will be.
Now check the operation of the soldering iron.The power supply is 5 Volts and the current is set to 5 Amps on the power supply, just in case, take the transistor case away from yourself for safety reasons.Put a button between the shutter and the drain, by pressing which you can turn on the soldering iron or by pressing-pressing the button to adjust its temperature.Also, the button can be installed between the shutter and the source, when pressed, you can turn off the soldering iron.Connect the plus power supply to the drain and the minus to the source.We press the shutter-drain button and the transistor flange heats up in 6 seconds, this is enough for the rosin to melt, after 15 the solder melts in seconds and soldering can be done.
After all the tests, I checked the transistor for characteristics and as you can see, the transistor is intact and in full health.And here are the main characteristics of the IRF3205 transistor:
- Drain-source voltage 55 Volts
The flow current is pulsed 110 amperes at 20 microseconds pulse
The resistance of the open channel is 8 mOhm, this is at a voltage at the gate of 10 Volts
Operating temperature from -55 to +175 degrees
Dissipating power with a 200 W case
