[SharpShooterSer]

Hi,
does someone have (or can draw) a simple schematic for the optical interrupter - that will work with LinuxCNC - with two sensors, Index and A. I want to use it with 5 axis breakout board, and I will use the ITR8102 for the build.
Thanks in advance!

[john-100]

Hi

assuming you use the same 5V supply that powers the breakout board
you will need a 330 ohm resistor to limit the LED's current to about 10mA
I've added a 1k pullup resistor to the phototransistor's collector in this diagram -

Attachment 329008

unless the errors I found with your breakout board, as sold 3 years ago, has been corrected
you may find the inputs don't work very well without adding a wire link to connect the +5V supply to pin 14 of the first 74hc14 IC - the one used for the inputs

with no +5V supply to pin 14 the 74hc14 only works (to a degree) with the current that flows via the various pullup resistors into the input and output pins
this current then passes through the IC's protection circuits to the supply pin 14 !!!!

john

PS

breakout board diagrams

Attachment 329010

Attachment 329012

[SharpShooterSer]

Hi

assuming you use the same 5V supply that powers the breakout board
you will need a 330 ohm resistor to limit the LED's current to about 10mA
I've added a 1k pullup resistor to the phototransistor's collector in this diagram -

Attachment 329008


unless the errors I found with your breakout board, as sold 3 years ago, has been corrected
you may find the inputs don't work very well without adding a wire link to connect the +5V supply to pin 14 of the first 74hc14 IC - the one used for the inputs

with no +5V supply to pin 14 the 74hc14 only works (to a degree) with the current that flows via the various pullup resistors into the input and output pins
this current then passes through the IC's protection circuits to the supply pin 14 !!!!

john

PS

breakout board diagrams

Attachment 329010

Attachment 329012

Hi John,
I will try to determine has the bib been upgraded regarding to pin14.
As for optos, the shematic is the same for using two of them? Just connecting to different pins for index/pulse a?
Thanks a lot!

[john-100]

Hi
just make two copies of the opto-interupter circuit one for the index input and another for the A input



John

[ninefinger]

Excellent timing - I have that BOB and was going to use it for a small lathe project. I'll make those +5v connections and I think I can avoid the use of the B axis connections in my case.
Thanks John and SharpShooterSer

Mike

[SharpShooterSer]

Hi John,
after a while with help from electrician friend, I ve managed to get it done. Board is having a proper supply on pin 14.

Optos are reading 4,2 V and 0,7 V open/closed - I suppose these are OK values?

Thanks

[john-100]

Hi

the voltage levels look OK

with the 74HC14 being a CMOS device a valid low level will be 0V up to 40% of the supply voltage
0V to 0.4 x 5V = 2V

a valid high will be a minimum of 60% of the supply voltage up to the supply voltage on pin14
0.6x 5 = 3V to +5V

John

PS

Comparison of 74HCT TTL
Compatible CMOS Logic
from Fairchild semiconductors

Attachment 330094





another chart found on the net for various devices

[SharpShooterSer]

Thank you John for your detailed help! I hope that it will be useful to others as well.

[john-100]

I'm sure it will

others are bound to ask the same question and find this thread and others like it


John