Want a battery spot welder that works for £20?

[docw009]

can anyone tell me howto change the welding mode to auto?,mines stuck in manual and i cant see how to set it to auto,cheers.

There are three buttons on the red welder. First two set the power duration up and down, right? Last one switches the welder to either fire with a foot switch or go automatic. If it doesn't work, then the circuit must have failed.

Are they still selling the version of the red welder that only needs a capacitor mod? I thought that later versions included the capacitor, but they changed other parts of the circuit so it still needed added modifications,

I still have the one I bought in 2021 that works, along with a spare.

 

[Daijoubu]

There's a very comprehensive video on the black boards GX590 here, you can do auto translation

Basically separate supply to prevent voltage sags causing FETs to not fully open/close and blow up, TVS diode to alleviate avalanche and resistor mod to allows the FETs to shutdown faster.

Luca also covers the same topic for the purple KEKK board, the black board optocoupler already decoupled through the 1000uF cap but still sags quite a bit at max pulse length of 35ms as per the first video and he suggests to have separate supply.

My understanding is that adding more FETs will just slow down switching as those boards lack a driver and rely only on the opto coupler, there's also only a single resistor in front of all the FETs as opposed to one per, which increases capacitance.

I'm gonna perform said mod and hope it won't blow up lol