Re: [CAD_CAM_EDM_DRO] Proper pull up resistors for optical limits

On Fri, 14 May 2004 02:16:27 -0000, you wrote:

>Wondering if anyone could give me advice on the correct pull up
>resistor for my optical limit/home switches. I'm placing slotted
>optical switches on the + side of my X,Y,Z axis to use as limit and
>home. My servos are WorldServo SST1500s and the manual suggests
>using optical switches on the + axis side. There is a diagram in
>the manual that shows connecting them to +5V (which is supplied by
>the servo through the limit switch plug). They show a resistor
>between the +5V and the optical interrupter switch but do not give a
>value on the resistor. I assume this is a pullup resistor (I know
>very little about this) and I'm wondering if anyone can help me with
>determining which size resistor to use???? The optical switches are
>transistor output type, Min Output 0.5 IC @ 20 mA IF. Another type
>I may use are the same except Min Output 1.8 IC @ 20 mA IF.

Use the first type, which can be interfaced to logic directly, the 0.5
volts is key, use a 1K resistor to +5 volts, which will use about 5 ma
of the 20 ma capability. Your gate will use at most 2.0 ma more, so
you have enough capability.

1K resistor can be 1/4 watt.

Harvey

>
>Thanks,
>
>Frank
>
>
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