Can someone help me put this together?

Is this what you want?

On 23 Oct 2005 08:49:55 -0700, snipped-for-privacy@willowcreek-wh.com wroth:

Are you expecting the motor to be reset somehow so that the whole operation automatically happens over again when the trigger arrives a second time?

It's fairly simple if the operation is a "once and only once" type.

Jim

schreef in bericht news: snipped-for-privacy@z14g2000cwz.googlegroups.com...

Well, there are more ways to skin a cat, but it also depends. So let's asume your SW1 makes contact for a while but brakes it shortly afterwards again. So see below: When SW1 closes relay A is powered and a turns off the motor. At the same time it shorts SW1 so when SW1 opens again the relay will stay on until power goes down.

It's elementary (Watson) that SW1 does not stay on because you may not be abel to start the motor again. So other variants of SW1 will require another solution.

petrus bitbyter

SWITCHED POWER IN>---+------O | |K1 [COIL]- -|

If the motor has enough momentum to drive past SW1 so that it closes momentarily and then opens again, your idea works, just put SW1 in series with self-latching R1 coil,like so. If SW1 doesn't reopen or something else happens so that it is in closed position when power is applied, then that's your problem. View in a fixed-width font such as Courier.

. . . -------+----------MOTOR------------+ . | | . | | . | | . ------------ R1----------------- . | | | | . | | - | | . | +-|\\| +-- NO NC ---+ | . | |\\| | | . | |\\| | | . | |\\|--+ | COM | . | - | | | | . -------------------------------- . | | | . +------+ | . | | . o | . SW1 |- | . o | . | | . ---------------+------------+ . .

Well- he said the motor "hits" the switch, and there are all sorts of mechanisms that will do that, so it's safe to assume the switch is pulsed ON momentarily regardless of further motor travel. Then the only requirement is that the switch close time exceeds R1 worst case activation time, and R1 is self-latching with power applied.

"John Fields" schreef in bericht news: snipped-for-privacy@4ax.com...

John,

As too often it all depends. This time the properties of SW1 stipulate the possibilities you have for a solution. In the simple ones, timing will be critical. For instance, when you assume SW1 to be a momentary switch, you must be sure the motor cannot stop while SW1 is closed. So the relay you use should be fast enough to be activated by SWI but SW1 (or the motor) should be fast enough to have SW1 released before the motor actually stops. Another SW1 requires another approach and you may need an extra relay or other electronics to make it work the way you want. Worsed case you cannot be sure whether or not SW1 is closed which requires some memory in a reliable circuit. I'm sure you are able to make a working circuit but I don't like to draw more schematics without more information from the side of the OP.

petrus bitbyter

That works- but is there an AC solution? Motor is heavily geared and turns slowly- stops on a dime.

Right- I was wondering about that. The only way this can work is to detect a transition from open to close and and vice versa in S1, any control relying on S1 static position or polarity of transition will fail. Forgetting about any particular hardware for the moment, if you can configure a detection circuit that is somehow "armed" by the sequence of S1 moving from initial to opposite state and then triggers the self-latching NC power relay when S1 returns to the initial state, this should do it. If power first comes up with S1 open, then the trigger arms when S1 closes and triggers motor off when S1 re-opens. If power comes up with S1 closed, the trigger arms when S1 opens, and triggers when S1 re-closes. The end result is that the motor always stops at the SW position after making at most one revolution. If you want the motor to fall into always stopping when S1 closes, then you could a timer that applies to the arming logic so that if S1 was open initially, but the motor has run a minimum predetermined time, the trigger logic will fire on first closure.

Well, maybe not for less hardware bux since the time delay relay is kind of expensive, but since it'll surely eliminate the need for grading the other relays in terms of speed, according to you, there'll be some cost advantage gained there...

Which relays did you have in mind?

"Fred Bloggs" schreef in bericht news: snipped-for-privacy@nospam.com...

Can't help but giving it a second look. I'm sure all simple solutions may run into timing or exception problems like I said before. The solution below is not very simple but should work always.

S can be omitted when SW1 has a normally closed contact that can stand the motor current, so SW1 can replace the s-contact. If you have to use the S-relay, it should be fast with respect to the A- and B-relays.

petrus bitbyter

I think that solution is perfect:-)

"John Fields" schreef in bericht news: snipped-for-privacy@4ax.com...

No particular relays in my mind. After alle I know too little about both the power and the motor although it should work on mains supply if I've understood well. As the S relay is only required to "invert" SW1, it should be at least as fast as the others unless you can power it independently. If that's the case it always reflects the state of SW1.

BTW. Using an (electronic?) delayed relay like you do makes me think about another type of solution. FAIK mains relays are pretty expensive. Relays that can switch mains power up to tens of amps using a 12V or 24V coil are less expensive but need quite some low voltage power. What about building a very small, low voltage, low current power supply and do it all in low voltage electronics? The only power relay you need can be a solid state relay which needs only 5V/10mA to switch on. Build a 5V/20mA power supply and you can even use a PIC :) to do the thinking.

petrus bitbyter