Click to return home.©

Object was to make, a simple circuit, with digital control of a 12Volt DC motor.

Resistor R 2R ladder and switching DC circuit, for adjustable motor control.

My own trash being my treasure.

Speed Control Menu.

Click on links to view images.

Making homemade photo-switch.

LM2575 "PCB Art".
   Click here for a video of it in action:                    And another via a tablet: Videos showing both running with latest setup, to compare performance.

Click me: With Switcher

Click me: With LM317

Click chart to see full size.

R 2R = Resistors 1 to 3, value is times two for resistors 4 to 8. Resistor Total "RT" value was measured.

  This is showing output of ohm meter, as 2R resistors are switched in and out, from ground reference to RT point with the circle.
  Doing a standard binary count from 0000 to 1111 we get a variable resistor measured from 124.8k ohms to 24.9k ohms. Calculations of:
0000 R4+R3+R2+R1 = 124.6k
1111 1/(1/(1/(1/(1/R4+1/R5)+R3)+1/R6+R2+(1/R7)+R1)+1/R8) = 24.9k

Link to spreadsheet r-2r_calculator.ods which you can plug in your own values.
Has been updated for 32 bit, video here.

Control a laser show.
Why buy SI/OP?