I did think of that Keep, but then there would be no way of turning the motor on.
In general, geared down motors don't tend to overrun too much and small motors don't tend to brake well by placing a short across them. I have proposed a braking diode though.
As a 3 Amp PSU is specified and the motor only takes around 1 amp worst case, say, you could put a 5.6 Ohm resistor across the motor to act as a brake if necessary.
spec
I don't quite understand what your trying to say. Not unusual.
Earlier I mentions lots of stuff goes into the selection and surplus parts isn;t a bad way to go for a one of especially if you buy two for the repair aspect.
I computerized a model gantry crane for a model railroad. It used 6 V geared motors. So, you can use an SPDT relay, just arrange it, so the motor is shorted when the relay is not energized. The motor acts as a generator into a short. For small motors, this works fine.
You missed the point. e.g. Common to Motor (+) , NC to ground, NO to +12, motor (-) to ground.
relay off: NC contact grounds motor
relay on: NO contact is now closed, powers motor(+) contact.
It's just not the NORMAL way to think.
So, you can still turn on the motor.
Aside: Some H-bridge ICs have FWD, REV, coast and brake options with the not enable being a way to introduce PWM for speed.
You can see the general idea here
**broken link removed** with a pic of "cam timers". For one position, you just need a circular depression.
**broken link removed**
This switch isn't a roller, but it works. I did a 4 position optical filter wheel with position indication using a variation of this method and a 24 VAC motor.
Aside: Since it was micro base, I could sense if the motor was running (I/O module) and I could bypass the switch. Two Hall effect sensors and screwable magnets could sense the position. 00 or 11 could be moving or position zero. When combined with not moving, the position was well known.
I did a film advance mechanism (timing and match based only) to move a PTFE curtain so it could pass UV light to the process. As the curtain fouled, a clean PTFE area was moved into place. So, timing worked there too.
I "mentioned" the likely 1 minute resolution of timers which you picked up on.
So, the main requirements are low voltage and a sealed mechanism (motor/switch) at least, A possible local push button to dump it manually.
The third requirement is the fill. This is where the smart relay could come in handy as well as knowing whether or not the bowl is moving.
A "future" enhancement might include empty bowl detection.
Dumping has the advantage of removing debris.
If we go yet another step, there could be a spray function added where the bowl is cleaned.
So, design the BMW (Cadilac) and then decide what functions are immediately needed.
Let's say rinsing would be a second position of inverted and a spray pointed up. With a "little" work, the two positions could be accommodated. A place to put the rinse nozzle could be designed, but not built. The box would be sized to accommodate two cams. Initial tests just done using time.
Dumping the bowl presently may tell you whether or not cleaning is necessary, but it may not because I bet someone automatically cleans the dish if it's dirty when it's filled.
Then there is the 12 VDC, 24 VAC, 120 V GFCI protected stuff etc.
What I have found is that no one knows what they really want until you build/program it. then they say ... Can you add this or that?
It's also agreed, that we don't know everything about the install. Inside/outside dump into ground or something else wasn't talked about, so we are just dealing with how to do it electro-mechanically. We start out with a "poor description" of the problem. I initially thought "dog water dish".