madhippiescientist
New Member
I have a Unipolar Driver / Motor (only one phase active with each pulse), that on occasion stops, and I found that if I disconnect the 74LS194's direction connections (from driver transistors), it starts back up. The "power up" start delay circuit doesn't work half of the time, but also if I have the motor go into backup (battery) power, I'm not there to push the DPDT Momentary to restart the motor. Worst of all, on rare occasion, after it's running, it will go into a condition of all phases (X1/Y1/X2/Y2, based on the X/Y axis principal) either staying on or staying off. Strangest of all, maybe because we get to close to the sun? (ha ha), it even hangs with X1 staying on and all other phases off (after it's been running). Maybe all of this is V cutout or insufficent A. I figured though, the way to solve this is to have a circuit monitor the motor, and a relay cut out the direction selections automatically.
So far, I have an X-OR made from a 7400 (Quad 2-input NAND) that drives an NPN to supply an astable 555 with a repeating Gnd signal to the reset pin (2), and I monitor the Y1 & X2 phases. It works great. If both of these phases are on, or both off, the timer powers up and sends a signal to the relay to reset the motor (via the 74194). Since X1 occasionally stays on all by itself it is not being monitored by my circuit and I haven't seen it keep any other phase on indefinately (like X1), so I don't see much concern with Y1 or X2 staying on. But if it does (one of them gets a low and the other a high without further oscillating), my X-NOR (X-OR & NPN) sends a low signal which STAYS on the reset pin / timer never starts charging.
I've thought this through, how can I possibly integrate determining that both of these inputs (Y1 & X2) "occasionally" oscillate (go low to high in each cycle), so I know that one of them is not "hanging"? I've thought of using JUST the inputs (w/o X-OR<w/NPN> // X-NOR), gating them WITH the X-NOR, and gating them at the end of the X-NOR's decision, but I can't finger this one out. Anybody have any ideas what gates and configuration to use? Remember, if Y1 or X2 is high and the other low, the X-OR (w/o the NPN) puts out a High, and the X-NOR puts out a low. I need a REPEATING low into the 555. Even with numerous additional transistors & chips, maybe I could do this, but I just can't figure out how to gate it all with the minimum number of discreet components and chips (maybe one chip and a few transistors). Anybody???
So far, I have an X-OR made from a 7400 (Quad 2-input NAND) that drives an NPN to supply an astable 555 with a repeating Gnd signal to the reset pin (2), and I monitor the Y1 & X2 phases. It works great. If both of these phases are on, or both off, the timer powers up and sends a signal to the relay to reset the motor (via the 74194). Since X1 occasionally stays on all by itself it is not being monitored by my circuit and I haven't seen it keep any other phase on indefinately (like X1), so I don't see much concern with Y1 or X2 staying on. But if it does (one of them gets a low and the other a high without further oscillating), my X-NOR (X-OR & NPN) sends a low signal which STAYS on the reset pin / timer never starts charging.
I've thought this through, how can I possibly integrate determining that both of these inputs (Y1 & X2) "occasionally" oscillate (go low to high in each cycle), so I know that one of them is not "hanging"? I've thought of using JUST the inputs (w/o X-OR<w/NPN> // X-NOR), gating them WITH the X-NOR, and gating them at the end of the X-NOR's decision, but I can't finger this one out. Anybody have any ideas what gates and configuration to use? Remember, if Y1 or X2 is high and the other low, the X-OR (w/o the NPN) puts out a High, and the X-NOR puts out a low. I need a REPEATING low into the 555. Even with numerous additional transistors & chips, maybe I could do this, but I just can't figure out how to gate it all with the minimum number of discreet components and chips (maybe one chip and a few transistors). Anybody???
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