XPost: sci.electronics.components, sci.electronics.design   
   From: not@home.cow   
      
   http://pdf.datasheetcatalog.com/datasheet/vishay/83725.pdf   
      
   The output transistor of the 4N25 optocoupler is spec’d at max 150 mA (no   
   mention of on-resistance). I measure the resistance across the output   
   terminals with the input driven with 17 mA and I see a little over 110 ohms.   
      
   This is going to operate the enable input of a VFD: 10 vdc high-impedance   
   digital input needs to be pulled to ground. I’m concerned whether or not   
   the 4N25 will do the job. With an on-resistance of 110 ohms, will this pull   
   the input low enough?   
      
   Maybe I should be looking at another optocoupler? What spec is important look   
   for?   
      
   Thanks,   
   Dave   
      
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