[Amps] 4 wire EBM Papst fan but without using PWM

[Ron Youvan]

    Conrad PA5Y wrote:

> I have a couple of EBM-PABST 3254J/2H3P fans which have a 4 wire
> interface. I do not want to use PWM and while they run with just the
> positive and negative DC voltage applied they tend to change speed in a
> random way when I run my amplifier without the PWM and tach wires
> floating. How can I ensure that the fan runs properly without using PWM?
> Can I just tie the PWM input high via a resistor and ignore the tach
> connection?

   see:

 
https://www.google.com/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1680&bih=834&q=four+wire+computer+fan+circuits&oq=four+wire+computer+fan+circuits&gs_l=img.3...4715.14290.0.15660.31.12.0.19.19.0.126.1050.8j4.12.0....0...1ac.1.64.img..0.23.1097...0j0i30k1j0i8i30k1j0i24k1.sYLU4-xnt2c

-- 
   Ron  KA4INM - Youvan's corollary:
                 Every action results in unwanted side effects.