rickyjar
Member level 2
User “tomasga” presents his soldering station with a symmetrical power supply.
At the beginning, it was planned to build two different devices but combing them into one decreases expenses and is more competitive to those that can be bought online.
The soldering station is a project from PE 3/99. Boards and printing is almost the same as in the original. A 1k resistor parallel to R1 and 470nF capacitor parallel to R5 were added. It prevented the relay from buzzing. Instead of R11 and R12, potentiometers were inserted in order to adjust the range 150mV-450mV on P3. It was calibrated through measuring voltage of the thermocouple. It is not the temperature of the tip but the device solders anyway “by sense”.
The section of the symmetrical power supply is a construction from EP 11/99. Two pairs of dismantled Darlington transistors MJH11022/MJH11019 were used as power transistors. The current of the power supply was restricted to 4A, voltage +/-15.
The measuring section consists of 2 voltmeter on ICL7107. Because there had already been the symmetrical power supply, the 7660 system was given up. To balance measurement, the range of the voltmeters was adjusted to 2V and an external reference voltage was added.
All is supplied with one toroidal transformer. The idea has been changing while constructing. Originally, it was supposed to be 2x12 4.1A. Secondary coils were wound. Finally, the transformer has 2x12 and 2x16, and its current efficiency is about 3A (with that load on the secondary coiling, it is 16.2V). The casing made of metal sheeting. The front printed with a laser printer and laminated.
Link to orignal thread - Zasilacz symetryczny i stacja lutownicza w jednym
