Noob needs help with opto isolator circuit.

Thread Starter

kawgomoo

Joined Aug 5, 2014
19
Yes, this machine has the manual option which powers up the spindle when you flip it, but it does not necessarily power down the steppers.

The steppers only come on or offline as a result of grounding pins on the stepper boards db25 connector. This is why the little dongle thing needs to work right, so it will shut down the steppers when no computer is present.

In the classroom these machines are generally used by high school kids. But in my own home, well…we would make OSHA's toes curl. lol. oh well.

I got mach3 turn figured out, i had to go in and manually change the skin. Even though you load turn, it still has the mill skin.

Need to get the watchdog/chargepump circuit figured out. The schottky diodes and irf530 transistor are not readily available at the only electronics store in town. I have a 555 timer, and have read this can be used to make the required circuit…but i haven't found a suitable diagram yet.

The 555 circuits i have breadboarded work as advertised, but I've yet to land on one that won't stay triggered if you "keep the button down" i.e. give it a steady state input of one form or another, be it high or low.

I'm assuming i need a "non retriggerable monostable multivibrator" but can't really figure out how to convert retriggerable into nonretriggerable… much less figuring what timing i need to turn on at approx 10khz, and not stay triggered if the port is either stuck high or stuck low.
 
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Thread Starter

kawgomoo

Joined Aug 5, 2014
19
Well, its done.

Ive built this circuit every way possible.

Turns out, Marris's diagram is the best one.

Also turns out the store DID have the cross reference for the IRF530. {Which is NTE66 in my case} The store computer said they didn't carry it, but there were a half dozen on the shelf.

Also these diodes are sort of huge, i am going to try and replace with a lower ampacity schottky and see if that doesn't help with the package size of this whole thing. As of right now it will easily fit where i need it to. But if i could shrink the diodes it would save a lot of space on the circuit board.

Just wanted to say thanks for the help!
 
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