heat-gun-firmware

A homebrew dual soldering station (soldering heat gun) with digital control.

For the schematics, see https://easyeda.com/barath.laci10/heat-gun

Note: I am desigining HW AC parts with 240V@Hz in mind. Adjust them to yor needs if necessary!

Project goals:

• temperature control (thermocouple read & adjust output power via phase cutting)
• 858 handle fan speed control & reed switch reading
• simple to use interface using 16x2 alphanumeric LCD & rotary encoder
• safe - no danger of electric shock
• simple to build - 1 layered PCB to make DIY etching possible
• cheap - at most half the prize of an already alaviable one
• opensource - mega328p + arduino code -> repairable

Progress:

• thing is built, firmware is working. Temperature control is working, albeit kinda shitty (simple on-off control), so improvements are possible.

Modules:

Main MCU(Mega328):

• xtal + 2 caps
• IC
• resistor pullup on reset
• (firmware)
• ISP header

LCD

• LCD
• contrast pot
• current limit resistor

Rotary switch

• rotary encoder

Fan speed control

• IRFZ44 fet
• 1N4007 as flyback
• gate pulldown resistor

Temperature control

Temperature reading

• MAX6675 breakout board via SPI

Triac control

• header to external board - 1 pin + gnd
• external board

ZCD (zero crossing detector)

• header to external board - 2 pin + gnd
• external board

Reed switch

• header - 1 pin + gnd

Heater ON

There are some inputs that control (enable or disable) the heating element:

• reed switch in handle
• swtich on front panel (or maybe a menu item?)

Heater is ON (controlled by feedback loop) if and only if reed detects picked up AND switch is on.