Soldering may sometimes make nuisance because the Iron will be either too hot or cold. If it is switched on continuously, it becomes too hot, wasting power and the bit gradually erodes. If it is switched off during a work, it takes time to become hot. So what is the solution to solve this problem? Do it, your Soldering Iron will always be ready in its two heat conditions. Simple, see how the trick works.
Most of the Soldering iron Tips or Bits now available are Copper core surrounded by Iron. It is coated with Nickel or Chromium to prevent the sticking of solder. If we switch on the soldering iron for long period, the excess heat may damage it permanently. If the soldering work is intermittent, it is ideal to keep the tip half warm. This circuit performs this function. It has a switch and if it is in the off position, the soldering iron tip remains half warm and if the switch is in the on position, within seconds, it will become fully heated
The Soldering Iron uses an AC outlet to power it. So just do this arrangement. A IN 5404 or IN 5204 diode is connected in series with the Phase line. An AC switch bypasses the diode. A Neon bulb with 82 K resistor runs parallel to the diode. So the current going to the AC socket has two paths.
So when you are doing the soldering work, just switch on the AC switch. Full wave AC passes to the Soldering Iron through the switch and it works in full heat. At this time, Neon turns off and indicates that, the Iron is in normal heat. Suppose you want a break during the work, switch off the AC switch. Now the current flows through the Diode and Neon turn on. The Iron will then get Half AC so that, it remains half warm and consumes, only half power. When the switch is turned on again, within seconds, the Iron will turn to normal heat.
The indications of the Neon are:
1. Neon off with switch on – Load (Soldering Iron) not connected to socket.
2. Neon off with switch on – Full AC to Soldering Iron and normal heat
3. Neon on – with switch off – Half AC to Soldering Iron and half heat
Caution : High volt AC in the circuit can give a fatal shock. Do not touch, or trouble shoot when connected to mains.