DIMMER CIRCUIT FOR 40W SOLDERING IRON: For everyday tasks, I prefer not to use overly expensive soldering irons. A 30W iron suffices for most applications, but when it comes to soldering thick cables or the chassis, it becomes quite challenging. In such situations, a 40W soldering iron is unavoidable, even though the affordability of these devices often leads to rapid deterioration.
I started exploring dimmer circuitry, thinking it might be more practical to invest in a modest 40W soldering iron and regulate its voltage using a dimmer. This approach ensures the soldering circuit remains intact and extends the lifespan of the power supply, maintaining a steady output between 25-30W.
DIMMER CIRCUIT DIAGRAM
The schematic shared in the provided link deviates slightly from the typical dimmer circuits. As far as I can tell, the author mentioned that it doesn’t produce any crackling noises or interference during operation.
Although there was no specific diagram available, I took the time to create a detailed soldering plan that could fit onto a 5 × 5 cm card. Previously, I had faced discomfort due to interference and unwanted noise in simpler dimmer circuits I had attempted. Surprisingly, in this particular circuit, I encountered neither of these issues. I am uncertain whether it’s due to interference from the mains network at the devil’s output or the revealed four-diode rectifying circuit, but my expectations were exceeded.
I opted for the BT138 triac to ensure reliability, and there are several suitable alternatives available. Despite the low load of 40W, I mounted a small aluminum plate onto the triac, although it barely heated up.
Regarding the filter coil, the screen indicated 47uH, but using 120uH didn’t cause any problems. I enclosed it in a small plastic box and affixed it under the table. Additionally, I added a label indicating the outlet type. Consequently, I created a socket controlled by voltage. However, I need to emphasize the importance of caution. If someone inadvertently plugs another device and reduces the voltage, it could potentially damage the connected device. To prevent this, I placed a warning label next to the outlet, ensuring others are aware of the limitations.
The voltage values noted on paper and those recorded with the avometer may slightly differ due to minimal fluctuations in the network voltage. During my initial measurement and documentation on paper, the mains voltage stood at 235 volts. However, when I took pictures later, the voltage had decreased to around 226 volts. When first switched on, the switch triggers at approximately 65-70V, regulated by potentiometers 1, 2, and 3. There isn’t a significant voltage variance across these stages. It’s worth noting that the potentiometer in the image includes a key switch, so if you’re purchasing, be mindful that these types are made of plastic.