Re: OCS 4 vs 3?


Howard Dutton
 
Edited

You know which I'd use, else Rev4 wouldn't exist, but its up to you.  AFAIK both designs should work fine (see notes below.)

I recently fixed silk screen and component values for some resistors so be sure to look at the latest PCB (both Rev3 and Rev4.)  On Rev3 I just kind of winged it (as the early prototype had bigger problems to worry about) then later built Rev4 to spec and it didn't work quite right, the SSR current limiting resistors were 3.3k and that just didn't quite turn them on (built in optocouplers) so I swapped in 2.2k and all was well.  The holding resistor for "normally closed" was much higher value also and wasn't doing the job so watch the new resistor values around there too.  The latest OCS4 uses the 3.3V rail for this purpose so its resistor has a fairly low value, my prototype Rev4 board uses the 5V rail, so feel free to pick a resistor pair that works for R300 and R301 such that Relay 8 is held closed during a reboot (while not overloading the Teensy pin) if you run into trouble with that.  Probably the spec'd values will work.

Eventually I will build up a Wiki here with assembly instructions to take some of the guess work out of it.  It will cover two designs, the OCS4 and the OCSESP1 (once its tested.)  OCS3 will become obsolete.

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