Electronics November 1, 2021


by kazawadi

The use of sunlight to dry maize after wash before milling process, but during the rain season. The challenges to cover all of the maize for drying when the rain fall due to the fact that the time to react is very small compare to the rate raining. So an automatic circuit design for driving a slide roof during rain moment to cover all grain will perform all activities.


  • No need for person to cover the grain, since the system is automatic. 
  • Time consuming and effort for grains covering minimized, since the system is automatic.
  • Damage of grain will reduced since the roof will protect it accurately.


Workers must be there for the covering of grain.

Rainfall grain gets wet, The grain takes more time to dry again after getting wet.


This system the means of covering of grain during the rain period in order to prevent the grain from wet. Since the system is automatic, The workers continues with other activities like milling and packaging the flour ready for selling while the system is performing the duty of covering the grain such as maize.

To calculate the mass of canvas.

Mass of Canvas for dimensions of 15m x12m=45kg. These calculations from standard weight and dimensions of Canvas

For 10m x11m =27.5kg of canvas,

For  8m x15m   =30 kg  of  canvas, that values nearest to required dimensions.

Then taken as an area,

8m x15m=120 m2 =30kg

12m x15m =180 m2, then 120 m2 =30kg

                                       180 m2=45kg

To calculate the force required to move the slide roof

Force = mass acceleration due to gravity

= (mass canvas + mass of single square bar) x acceleration due to gravity.                                                                                     = (45kg+8.1kg) x 9.8N/kg


          To calculate work done due to gravity

Work done=Force x Distance moved by the roof

                  = 520.38 x 14m = 7285.5J       

To calculate the friction force

Friction force = Force x coefficient of friction

                        = 520.38 x 0.5 = 260.19N

To calculate work done due to friction 

Work done = Friction force x distance of contact

                   = 260.19 x 15m = 3902.85J

To calculate power needed to overcome friction force

    Power = Work done due to gravity/time

               = 3902.85/35

               = 111.51W

Finding  Resistance

We are using transistor NPN

For NPN transistor we have different categories, for example BC 547,BC 548,BC 549 and standard collector current,Ic=200mA and its β is about 120-150 and Ib ≥1µA



    =12V/200mA,RC=6,000Ω or 6kΩ,

 then RC=R1=R2=R5= 6kΩ.


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