PWM Multiplexor?

[Jump21]

I noticed that the 74AC138 decoders used for the PWM multiplexor are active low.

it is my understanding that the servos are active high devices.
My question is: the signal line for the servo sitting at +5V if it is not being controlled, shouldn't it be sitting at 0V instead?
how do you get around this problem?

Thanks

[Matt Denton]

Hi,

The multiplexors used are actually HC238 active high decoders. The schematic whihc I presume is where you got the 74AC138 from is wrong. I couldn't find the HC238 in the PCB schematic library, so I used 74AC138 instead which is pin compatible. Sorry for the confusion

[Jump21]

You're right, I got the the 74AC138 from the schmatic.

The 238 makes a whole lot more senese.
Thanks for clearing that up.

Thank You!