This control panel of the spot welding machine is independently developed for the DIY or the simple resistance welding. The principle of silicone controlled phase shifting triggering is adopted to adjust the time and the current to achieve the purpose of welding. Equipped with digital display, you can see the time and current directly, simple and easy to use. Strong and weak electricity is isolated by optocoupler, to operate. Using high precisions single bit potentiometer, to reliable and convenient input. A reliable zero-crossing detection circuit to that the SCR phase accurate. : Name: Spot Welding Tool Set Type: 9V 40A Voltage: AC220V Colour: Red Material: metal, plastic Package Contents: 1 set x Spot welding machine control board Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.