Simple power controller for a soldering iron

[Vermes]

When you have a soldering iron, its continuous operation can result in too high temperature of the tip. The system is an expanded version of a simple soldering station. It is a combination of a simple generator on NE555 and SRR.

You can fix the values of elements (mostly those responsible for time constants) after drawing a schematic and using some simple formulas. You can use a simple simulation in LTSpice to check whether previous findings were correct. The main element of the device are two NE555, one of which is configured as unstable generator (of quite low frequency), its fullfilment can be regulated using a potentiometer. Another NE555 is responsible for fast heating the soldering iron. When the power is on for a certain time, which can be changed using a small assembly potentiometer, the soldering iron is on permanently. After that, the system goes into periodic heating. Because of the large time constant of a soldering iron, such periodic reheating makes it possible to control temperature. Executive module is a triac controlled by a popular optotriac with detection of transition through zero, what provides minimizing of the noise produced. Although it is a simple system, it is very useful if you do not have a factory driver.

Pictures:



Link to original thread (useful attachment) - Prosty projekt regulatora mocy do lutownicy

 

[D.A.(Tony)Stewart]

When I was in R&D back in mid 70's our techs at Bristol Aerospace used simple triac controlled 25W irons to control temperature that were left on all day, typ. 65%.

- Later when Weller had fancy temp controlled irons, these were preferred.

- But triac control is cheap, but your method is quicker to startup.

- I would choose a thermal sensor with some thermal insulation so a std diode or thermistor could be used at say 100'C instead of 300'C, so proprtional closed loop control can be effected.

- To drive triac... I would use XOR gate on ac bridge signal clipped to generate ZCS pulses ( at zero crossing) 1;1 simple pulse transformer would work find driven from CMOS.

- Weller was notorious for causing glitches with random bit-errors in the lab and non ZCS control.

Thanks for sharing.

 

[raveesh.hp]

When you have a soldering iron, its continuous operation can result in too high temperature of the tip. The system is an expanded version of a simple soldering station. It is a combination of a simple generator on NE555 and SRR.

You can fix the values of elements (mostly those responsible for time constants) after drawing a schematic and using some simple formulas. You can use a simple simulation in LTSpice to check whether previous findings were correct. The main element of the device are two NE555, one of which is configured as unstable generator (of quite low frequency), its fullfilment can be regulated using a potentiometer. Another NE555 is responsible for fast heating the soldering iron. When the power is on for a certain time, which can be changed using a small assembly potentiometer, the soldering iron is on permanently. After that, the system goes into periodic heating. Because of the large time constant of a soldering iron, such periodic reheating makes it possible to control temperature. Executive module is a triac controlled by a popular optotriac with detection of transition through zero, what provides minimizing of the noise produced. Although it is a simple system, it is very useful if you do not have a factory driver.

Pictures:



Link to original thread (useful attachment) - Prosty projekt regulatora mocy do lutownicy

Where to get the english version of the construction details of the original thread