I found somethig similar surfing the web, but it seems more "professional" and maybe more developed. It's John Rogers presents Making Biochar for small acreage farms. You can find it in You Tube and is very complete and interesting. Check it out. I'm getting into this.
Virgilio Ortega Dominican Rep.
Thanks Virgilio, I've not seen quite this design before but it is very simple and effective. The TLUD method is how we make our biochar at home, but we don't have the after burner.
My thoughts on his method - he might find he gets a cleaner burn if he adds a few more vents higher up the afterburner.
Not everyone has the luxury of pre shredded agricultural wastes. When you try to do this with ordinary yard waste (hedge trimmings etc...) the variable thicknesses and structure of it makes for an uneven burn. Some material will be burning away while others are not charred through. The final quality of biochar is slightly less good but still fine to add to soil.