Posted Wiki Article on Building a PWM Controlled Stir Plate

I finally finished an article on building a PWM (Pulse Width Modulation) controlled stir plate: PWM stir plate design. Building the control logic was a fun project for me since building electronic circuits was a hobby of mine before I got a job in the computer industry. Many years after I build my first stir plate I once again looked into building a stir plate  because needed more stir plates for the yeast starter experiments I’m doing.  I knew I needed better fan speed control than using linear voltage controller since it was really hard to control the fan speed in my old stir plate design. PWM control does work much better but takes a few more parts and soldering skills.

PWM controlled double stir plate

8 thoughts on “Posted Wiki Article on Building a PWM Controlled Stir Plate

  1. Looking at your PWM build on, the schematic shows pin 4 and 8 on the 555 chip tied together going to vcc, but in the board layout pin 4 does not. Am I not seeing it??



  2. Hi, Thanks for putting this up. I have a question – I dont know too much about circuits and such, but im determined to build a working one without blowing up or burning down the house. So far i’ve got one built but cant get it to work. i’ve done a bunch of trouble shooting and cant find anything except on the wiki page the breadboard layout has “SDG”. I dont see that on the parts list and after much web searching i woud guess that SDG (Source, Drain, Gate?) is some sort of JFET? and then there is an N and a P channels? But maybe its something else.
    thanks in advance

    • Thanks for pointing this out. I forgot to label the MOSFET on the schematic and mention it in the parts list. This has now been updated on the Wiki page.

  3. Kai,

    Thanks for the circuit diagram, and the write up. I think I’m going to clone your design for the stir plate, but I am trying to select a timing chip. The NE555N is no longer available through Mouser, do you know what I should look for as a replacement?



  4. Kai,
    I have a question – I dont know too much about circuits and when I boght this parts the vendor sell me a Mosfet P. It is possible to use in this circuit? If true, what changes I need to do?

  5. Kai,

    Thank you for circuit diagram. I dont know too much about circuits, but I will try to mount it. I bought every component but the seller send me a Mosfet P-type. I mounted everyone as described in breadboard layout but this only is turned on when I remove the wire on 555 PIN 1.


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