I've got a radio-controlled step-sequencer/driver built, tested, and functional for driving a single steper motor.
As it sits, it controls one stepper motor - Call that one "Stepper A." The four separate outputs of the sequencer are each as shown in the "Driver" drawing below. Each connects to a "Phase #" line in the "Motor side" drawing below that. The line of "========" in the "Motor side" drawing is the demarcation between the existing circuit (above the line) and proposed additions (below the line.)
My goal is to control a second stepper - Call this one "Stepper B" - separately from the first. At any given moment, Stepper A might be active, OR Stepper B might be active, or both might be INACTIVE, but there will (or at least, according to plans, there *SHOULD*) never be a time when both A and B are active simultaneously.
I've been doing some thinking, and it seems as though I should be able to do what I'm looking for WITHOUT building a second sequencer and the associated circuitry that goes with it. Existing circuitry on the R/C board I'm already controlling "Stepper A" with can easily provide me with an A and a B signal, to drive points A and B in the "Proposed additions" section of the drawing.
What I'm looking for is someone to confirm or deny the sanity involved in my thinking.
Anybody see anything blatantly wrong with my "brainstorm" as drawn below? (ignore "cosmetics" such as lack of any back-EMF diodes in the drawing - it's much simpler for me to draw it without them, with the understanding that they are needed, and actually present, in the circuit)
I *AM* wondering if I ought to toss some "steering" diodes in between Stepper A and Stepper B, say at the locations marked "D?" though... Good idea, or unneccesary "overkill"?
Driver (four separate circuits, all identical)
,------O Phase "X" |E (To "Motor Side" phases, below) B | Control "X" O-----------K NPN (2N6387) (from sequencer logic |C via optocoupler) | | --- -
Motor side Phase 1 O--+-------D?---UUU---, ---, | | | Phase 2 O--(-+-----D?---UUU---+ | | | +------, |--- Stepper A Phase 3 O--(-(-+---D?---UUU---+ | | | | | | | | Phase 4 O--(-(-(-+-D?---UUU---' | ---' | | | | | | | | | +------------O +12VDC | | | | | Present stepper power connection | | | | | (would be deleted for the | | | | | second motor/selector additions) | | | | | ======================================================================== | | | | | | | | | | | | | `------UUU---, | ---, | | | | | | | | `--------UUU---+ | | | | +---, | |--- Stepper B | `----------UUU---+ | | | | | | | | `------------UUU---' | | ---' | | | | Proposed motor "selector" ,-------------------' | and second stepper motor | | additions B |C | B O----------K NPN (2N6387) | |E | | |
+12VDC O------+ | |E | B | | A O----------K NPN (2N6387) | |C | | | `----------------------'