To prevent catastrophic failure or "stuck" pulses, a hardware watchdog circuit limits the maximum pulse duration to 250ms .
Look for a very low resistance resistor (0.5 mOhm to 1 mOhm) in the high-current path. This is a "current viewing resistor." The voltage drop across this tiny resistor is proportional to the weld current. This signal is amplified by an Op-Amp (Operational Amplifier) and fed back to the MCU.
~120 µOhm (switch only) / ~3.2 mOhm (total with stock cables) Current Measurement Real-time integrated energy (Joules) Power Supply Requirements kweld schematic
The kWeld operates by controlled short-circuiting of a high-current power source. Its architecture is built to handle extreme electrical stress while maintaining precision.
: The circuit includes sensors for input/output voltage, switching current, and logic supply voltage, all managed by an STM32 F1 series microcontroller. To prevent catastrophic failure or "stuck" pulses, a
The design utilizes large copper areas on the PCB and CNC-machined brass bus bars to minimize internal resistance, typically measured at just 120–170 µOhm .
: The core of the schematic is an extremely rugged MOSFET-based power switch designed to handle a maximum switching current of 2000A . This signal is amplified by an Op-Amp (Operational
| Symptom | Check on Schematic | Likely Failure | | :--- | :--- | :--- | | "Low Voltage" error | 12V input stage | Dead battery or voltage regulator | | Welds but no display | I2C/SPI lines | Loose display cable or dead OLED | | Fires continuously | Gate driver output | Shorted MOSFET (Drain-Gate) or dead MCU pin | | Weak welds, high resistance warning | Current shunt & Op-Amp | Corroded shunt connection or blown Op-Amp | | No pulse at all | Trigger input | Broken foot pedal or pull-up resistor |