Overwater timer for center pivot irrigation

inwo

Joined Nov 7, 2013
2,419
That place is right down the street from where I work. We have some 3-1/2" aluminum for another project, so maybe we'll just try and make a wheel.
Surplus center?

I buy from them quite a bit!

At least I did before my brother opened a store.

Do they have a retail store? I bet they have unlisted items.
 

Bernard

Joined Aug 7, 2008
5,784
I have a 2" Al, 6 mm bore pulley which could be used as is or add plexiglass wheel of desired dia, up to 7" dia., with O ring drive belt, & ss set screws, cost-- just O ring & set screws, & postage.
Any answer to post # 59 ?
I'm going to buy me a 600 PPR encoder to play with.
PS: Does warning LED stay on untill manually reset?; Up-dn counter can also be used to divide & pre-condition a forward count for commercial timer.
 
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Thread Starter

djreiswig

Joined Aug 8, 2008
120
inwo:
Yes, they have a retail store. Not much, just some shelves of parts and a counter. Their warehouse is in the back. I think most if not all of what they have is on their website.

Bernard:
I will keep your pulley in mind. I think we may try and make one from the 3-1/4" aluminum. Thanks for the offer.

About post #59. I'm not sure how this would fit in with what inwo has designed. I think I'll get the 400P/R encoder from the US ebay seller.

I'll probably try and order the parts tonight.
Where's a good place to get a sealed panel that will hold the 2 timers and then encoder. Probably steel, but I guess plastic would work. Who sell's them cheap?
 

inwo

Joined Nov 7, 2013
2,419
Don't discount the 555 circuit.

As you have 12V available it makes sense.

Actually, you may find someone on here to make one for fun. At least simulate it.

I usually go for the timer relays, because they have so many things built in. Adjustment pot, output relay, input conditioning, rugged design.

I'm still waiting for opinions of latest schematic. Can't actually test it (easily), as my encoder is ttl and my timer is 120vac.:(

If you have trouble, I may feel responsible enough to put something together here.:D

I'd connect encoder to a small motor.

Local electrical supply co. will have pvc enclosures.
 

Thread Starter

djreiswig

Joined Aug 8, 2008
120
I think the local board store has plastic boxes, but I thought there might be something cheaper online. I'll have to check ebay tonight.

I think I'll try and order the parts tonight, unless you want to explore the 555 timer option. It would probably be simpler to just use the timer relays.
 

inwo

Joined Nov 7, 2013
2,419
Unless it's a hobby or you need 10 or more, stick with timer relays. IMO

(if it works):eek:

Haven't heard to the contrary!
 

Thread Starter

djreiswig

Joined Aug 8, 2008
120
I just ordered the parts. Hopefully they'll show up by the weekend. Then I may need some help with the wiring, although the schematic looks pretty good.

What sort of settings do I need to set the timers to? In simple language, what does each one of them do? I assume the second timer is the desired time before shutting down, but what does the first one do? Is that what will eliminate the jitter?
 

inwo

Joined Nov 7, 2013
2,419
Yes, set the second one for the time it waits with no pulses before it shuts down.

Any pulse will restart time it.

Even if it's in alarm mode, if there is movement, time will restart.

Set the first one (IMO) to half the normal pulse period.

It will only reset the second timer if it gets a signal from the encoder that is longer than it's setting.

So if your system (speed-gearing-P/R), puts out square waves 2 minutes high and 2 minutes low (4minute pulses), set the debounce timer to 1 minute.

It will ignore any lows less than 1 minute, and all highs. (As timers start on being pulled low by open collector outputs.)

If it stops on a low, it will of course (start) hold 2nd timer "on". Being an "interval" timer it will time out and re-close the nc. contacts. (alarm)

If 2nd timer gets no start signals it will just sit with it's normally closed contacts closed. (alarm)

That is the normal start-up sequence. Alarm until first pulse.
 

inwo

Joined Nov 7, 2013
2,419
I just ordered the parts. Hopefully they'll show up by the weekend. Then I may need some help with the wiring, although the schematic looks pretty good.

What sort of settings do I need to set the timers to? In simple language, what does each one of them do? I assume the second timer is the desired time before shutting down, but what does the first one do? Is that what will eliminate the jitter?
Timer 1 set to "signal on/off delay"
Timer 2 set to "interval"

1st timer follows start pin after delay. Pulses shorter than set time ignored.

Interval changes state with start signal only for duration of "time setting". No matter what start does.
Except:
Time starts over with each "toggle of start pin. (retriggerable)
 
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Bernard

Joined Aug 7, 2008
5,784
I have a drawing for 3 motor control, alas my printer died. Quick over view of operation: Parts, 2 555's, U-1 as flip-flop, U-2 one shot one hour timer, & relay, DPDT. Cycle starts with manual triggering of U-2, at time out pin 7 goes lo, C coupled to U-1 pin 2, setting FF, pin 3 hi on G of FET, D lo turning on winch motors M-A, M-B, & relay, RY. Clutch motor, M-C, is powered thru SW-D, opens when weight reaches top, & RY contact. When R-Y is on M-C rotates to engage gears, & when it moves to limit, opens SW-D stopping M-C; M-A & M-B lift weight untill it closes SW-E which puts a pulse on pin 6 of U-1, re setting FF making pin 7 lo , coupled to pin 2 of U-2 restarting cycle. With RY off, cross coupled contacts reverses M-C ,disengaging gears allowing weight to fall, & stops when limit SW-F opens.
Now to find a printer.
 

inwo

Joined Nov 7, 2013
2,419
I did some editing, as I didn't want the errors in previous schematic.

I built a timer control for OP in another thread and discovered that the 11 pin timers didn't work as expected in the delay on mode.:(

I thought the output would follow the start pin but delay on. (as do 8 pin timers)
Actually start pin sets a latch and times out. (like 555) Reset only by the reset pin.

However the signal on/off delay does follow the start pin with a delay on and off.

This seems perfect when tested.

Setting the timer to 4 seconds and randomly triggering pin 2 to pin 6, timer output would not change state, unless on or off pulse exceeded 4 sec. (except for start-up pulses)

When scaled up to 5M it should work the same. I hope.:D

When you get your timers, you can test the same way.
Power to 2 and 10.
switch from 2 to 6 to simulate encoder.
Ohmmeter or test light across N.C.
 

Thread Starter

djreiswig

Joined Aug 8, 2008
120
I have all of the parts. Can you post a new schematic so I can wire it up according to the changes you have made? I will try and test the timers like you suggested.

Edit:
I see the original schematic post was edited at 9:59pm on the 16th. This was just before you posted the above message. I'm guessing you re-uploaded the schematic as I didn't notice any other changes to the post.
 

inwo

Joined Nov 7, 2013
2,419
The first thing I suggest is to check the timers out to see if they work like mine.

On mine, power connects, neg to 2 and pos to 10.

Set 2nd timer to interval. "E" on mine. And time to something easy to watch, like 5 seconds.

Connect a short lead to 2 and 6. (com and start)


Shorting these two wires momentarily will turn output on for "time".

If you continue to short wires output will go off after delay.
If you stop pulsing output will also go off.

This is what you need.

Only by continually pulsing pin 6 can you keep output on.

Off = alarm.

I hope that makes sense.

If you want to test system with just this one timer, go for it. Simple is good.
Pulsing pin 6 is what the encoder would do. Just a much longer time between pulses.
 
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inwo

Joined Nov 7, 2013
2,419
The first relay conditions the signal from the encoder.

It will only change states when it receives an encoder pulse that is longer than the set "time".

To test it. Connect the same as timer 2.

Set to on/off delay. "C" on mine.

Now connect 2 to 6 momentarily simulating pulses from encoder.

Relay will click on for "time".

If you pulse pin 6 continually with no on or off times longer than set "time", timer will stay "on". (no pulses get thru to 30M alarm timer)

This is what we want. ( I hope) It will ignore any noise or short pulses from encoder.

If timer is set to 5 seconds and you connect pin 2 to pin 6 for 6 seconds then off for 6 seconds, each change will activate the timer output relay. (clicks)

After encoder is mounted and we know the pulse period we can set the time to match.

Encoder output is square if speed is constant. ie. it may be on for 1 minutes then off for 1 minutes. We could then set timer to 30 seconds.


I hope you follow this as it will be hard to debug and get settings right if we are not on the same page.

It should be clear when you see how timers act.
 

Thread Starter

djreiswig

Joined Aug 8, 2008
120
I read through the two posts, and I think what you described makes sense. As soon as I find a 12V power source (wall wart or something) around here, I'll try and test the timers and see if that is how they work. I'll post back and let you know my findings.
 

Thread Starter

djreiswig

Joined Aug 8, 2008
120
Found my 12v car jump box.

Both timer modes work exactly as you describe. I have I for interval and D for ON/OFF delay.

So, is the schematic you posted the way the two timers and encoder should be connected?

My encoder has 4 wires. I'm guessing the VCC is +, the GND is - and the A & B go to 2 and 6 on the first timer.

The contacts on the first timer switch 2 & 6 on the second timer, and the contacts on the second timer are the alarm circuit.

Will I need to put a momentary switch in this circuit somewhere to jump start everything? Or will the initial power on get things going?
 
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