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Forum Index : Electronics : 12v Dc timer module SILCON CHIP MAG
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Lapsy Senior Member  Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Let me have a think about it for a while... the above is an example, the method is no problem regarding the circuit idea. I'm happy with that... Actually thinking about this, we are doing the same thing if we used 2 floats (although I don't have 2 floats at the moment, I could easy get another). I will also think about the arlec. Regarding - What metal would you use? You need something that won't oxidise or corrode. If it can be replaceable that may not be an issue. Has to be something out there where this type of device has been manufactured into it. I need to find and have a look at that so I can maybe steal some ideas. Back in a bit.... This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| larny Guru  Joined: 31/10/2011 Location: AustraliaPosts: 346 |
You could also use a Float Switch at the top & a Water sensor at the bottom or vice versa. I would still like to know the resistor values in the Arlec. Here is a scan from Silicon Chip. He used stainless steel rod. Brass may work. But not if it develops an insulating film on it after a few months. 
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
I'm Back! Got to work on a few other things lately. Took a break from this project as I felt I was getting nowhere fast either way and put a fair few hours of thought and tinkering on it so.... While pondering this..... I leaned back to the float idea. I figure it saves time teaching an elderly person how to program a timer and all that bizzo. Wondering again about the timed trigger for the float. When the water rises and triggers the float switch, I recon I want to keep the switch open of a period of time. How long (Power on) is the question, and can it be easy made variable? I probably don't need a full blown timer for one area I want to cover. But to get the switch to power open for about 30 seconds to about 3 - 5 minutes would be a start. The timer would depend on the reservoir size and how long it takes to empty. I would also like to think about upgrading the reservoir to a larger volume eventually. Will look further into the timer later. I am seeing a DC 12v timer on ebay for about $9 shipped so may look into that. The Arlec I will get around to repairing when I get things moving along a bit. The info is there I just need to feel enthusiastic about it one day and get on it. This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| larny Guru Joined: 31/10/2011 Location: AustraliaPosts: 346 |
You could have a a switch for course adjustment & a potentiometer for fine adjustment. For example, the switch could have 5 positions to give say 10 s to 1 min, 1 min to 2 min, 2 min to 3 min, 3 min to 4 min, 4 min to 5 min. Rotary switches are available for any number of positions up to 12. |
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| larny Guru Joined: 31/10/2011 Location: AustraliaPosts: 346 |
I have been thinking about your project and I feel that the best solution is to use a microcontroller. I can write programmes for the PIC (programmable integrated circuit) type of microcontroller. I can also load the programme into the PIC. So I can send you a pre-programmed PIC and other parts so you can solder them onto a prototyping PCB. This means that the clock would be inside the PIC, so you would not need an additional timer. Semtronics sell the PIC 12F675 for about $3. The only other parts you would need would be a PCB, a switch, a voltage regulator & a potentiometer. I can give you the remaining sundry components. So the whole cost should be less than $8, not including postage. All I need to know is exactly what you want. We can discuss the details in future posts. Len |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
No worries, sounds interesting. So I gather the programmable chip could be programed for a number a variable settings? The potentiometer is a good idea, forgot about those. I get what you are saying buy having an electronic flow dial for the pump. Not much time on my hands as I write this, about to leave and go out for a few hours, but though I would drop a quick post. as far as your response - I assume you mean that you want to keep the pump running for some time after the Float Switch triggers? The answer is yes, and if it is variable delay/timing then that would save a whole lot of hassle, rather than getting measurements e.c.t specifically correct for something that does not exist yet. I would only be hypothetically speaking/imagining/guessing, and no doubt, when you put things into play, there will probably be an unaccounted factor to tweak. I guess I am after something I can play around with. Modifiable settings.... and it would be good if it could be used universally on 12v devices. I may go for a gravity solenoid later on down the track, upgrade from a pump for less wear and tear/moving parts/maintenance. Anyways..... have a think when you have time. All suggestions considered. Mainly I feel some of the elderly do not like programming things. If I could just turn a dial and click it into a desired timing preset (Even if it was just set to say 5 settings say.. 1 min, 2 min, 3 min, 4 min, 5 min) that's easy! Can always run the thing through twice if required, or make it go off more frequent. O.k then! I must run along now! Places to be & people to see! Have a good one in the meantime! This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| larny Guru Joined: 31/10/2011 Location: AustraliaPosts: 346 |
Here is an alternative idea. The drawing is pretty rough and ready, but I think you will see the basic idea. This would avoid having to make the pump run for a particular time period after being triggered by the float switch. So the only timing you would need, would be to start the pump initially, and then, the float switch as shown in the diagram below, would switch the pump on and off as necessary. After a suitable time, the PIC timer would switch off & thus stop the process. The PIC programme could be designed to run the pump at particular times during the day or night. The start & stop times could be set by a rotary switch & push button. The overall running time could be set by the potentiometer. 
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Ok, Interesting.... I am thinking about the switches you get on video game machines for the controllers. Unsure of the actual specific name for this microswitch (maybe you are familiar), I know it is momentary with a lever. Have a look at the switches on this video game joystick -----> here... Looking on Element 14's site I found this ----> Plunger Microswitch... The lever would be very useful for this. I like it! I shall ponder further...... it is quite an adaptable setup and very simple with minimal parts. Very "bush mechanic" style! Good Stuff! This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Just logged out, went for a search, now logged back in to present a better micro switch picture ----> here... This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| larny Guru Joined: 31/10/2011 Location: AustraliaPosts: 346 |
Well that is a coincidence. I started thinking about microswitches this morning & drew the picture below before I switched the computer on. You can extract microswitches from a variety of defunct appliances such as dishwashers, microwaves, etc. They use them to detect when the door is open. Also, cars have switches in their doors for the interior light. However, if you open a microwave - BE CAREFUL - as they have a capacitor that is charged to about 3000 Volt! AND it remains charged for days or even weeks (possibly months) after the power is turned off. So you could kill yourself stone dead if you touched it or one of the wires that is connected to it. You could discharge it using a screwdriver with a plastic handle. Touch the metal part of the driver on the frame and slide the tip towards the capacitor terminal. You should see an arc (if the cap is still charged) when it is close to the terminal - provided that you touch the correct terminal as the other side of the cap will be connected to the frame. It might even melt a small piece out of the driver, so it would be a good idea to tie a piece of wire to the driver so the wire touches the cap & thus suffers the damage. Len 
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Nah Buggar the microwave! I not touching that. Chucked a Panasonic one out recently. I had an idea once, make the microwave work with the door open and point it at people you don't like and cook them from the inside out hahahaha! (This sounds stupid, but on the flip side there is someone probably researching these types of wepons somewhere... more than likely..... in the U.S.A of all places!) Anyways... back to the bizzo.... microswitches! Now.... your new diagram is good. The switches are cheap! The momentary switch is the only thing different to the toggle. The issue is not getting this float stuck in between the switches. Its good that the float rises and lifts off the E.G Pump Switch on the bottom. The moment it hits the release switch, wont the float just fall back onto the pump switch and end up in a vicious circle of operation? I still feel a circuit with power on for say 30 seconds or something would prevent the float acting as a tennis ball between to switches going back and forth. That way the reservoir could empty completely out. Then again... positioning of the switches might cancel out this problem. I need to think more about it, it is a fresh idea. Liking it though! Also, a timed circuit of some sort to keep the power on for a certain time, would be useful alongside the plastic float valve I obtained. I would say it would be worth my while learning something about building this type of thing. Then again if its $20 in parts for a 30 sec timer, it's not worth it. This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| larny Guru Joined: 31/10/2011 Location: AustraliaPosts: 346 |
I'm not too sure what your problem is with the micro switch idea. So I explain the sequence so you can see how it would work. As an example, assume that the tank is empty and the timer is set to start the process at 8 AM. At 8 AM, the timer would operate the relay & thus start the pump. When the water level rises to the point where the upper switch (call it SU) goes open, the relay would release and the pump would stop. When the water level falls to the point where the lower switch (call it SL) closes, the relay would re-operate, the pump would start again, the water level would rise until SU goes open, etc. This process will continue until the timer switches off. However, if the pump is running at that point, it will continue running until the water level reaches the maximum where SU will go open, release the relay & the stop pump. But in this case, the relay won't operate again when the tank is empty. If you only wanted one cycle, you would set the timer to be on for only a second or two - just long enough to start the process. In this case, the relay would release as usual when the tank is full, but it will not re-operate when the tank is empty. The circuit will then wait until the timer re-starts the process. So you could, for example, set the timer to start the process at say 8 am, 1 pm & 5 pm. Len |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
O.K hopefully I explain this right..... I think because these switches are momentary, it will be a problem (maybe, unless I am overlooking something). So.... say the bucket or whatever is empty. Therefore the float is pressing on the pump (fill) switch (Or SL as you named it). Pump activates and flows water into the E.G bucket. Float rises with the water level... Now once the water level rises to a point, the (SL) switch will no longer have lever pressure on the switch, which will stop the pump. I guess at this time you would want to have the correct volume of water desired to be ready for release. So this switch would be setting your waters max volume/height in the bucket. O.k so now we have the water ,the pump has stopped and say we have hit the release switch (SU). What happens when the release switch is no longer pressed (as the float slooowly drops down? Does the release of the water stop? If so.. then I think the float may be stuck in no mans land and not even finish the first cycle. Unable to get back to contact with either micro switch. This is where I thought a 30 sec delay timer would come in nice, to make sure this does not happen, forcing the water to empty as this timer delay circuit thingymajig over rides the no mans land area, to return the float to the beginning of the cycle. I may be missing something somewhere, but your idea would be great also (Minus the delay/timer/over rider), if the E.G Bucket could fill up way quicker than it could exit. And if there was say a small hole in the bucket, to release the water slowly, the float would have no option but to fall back onto the pump activator switch (SL) once the water ran out of the bucket. Problem with this (I think maybe), is stopping it going off frequently without reducing the outlet, to an absolute trickle of water. As this would determine how often the cycle was restarted. Then again you could just increase the buckets size so there is more water to exit, and it takes longer. This may be a good way to go about it....? Thinking about this further, using the original Jaycar type float switch upside down may be a good idea. So as the float levels out (as we run out of water), this then kicks the pump on to refill. But then again the floats 15mm of play or whatever would probably require a big wide bucket (thinking width-ways for volume of water). Unsure till I think more about it. In a nutshell I suppose the main problem here, is probably the momentary switches, where as the toggle switch when switched to ON, also forces the float to reach the off position eventually, preventing a no mans land and a stranded float. That's my 2 cents on this for the meantime. No doubt you will come up with an idea!  Your input to this thread has been great! Much appreciate the assistance!This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| larny Guru Joined: 31/10/2011 Location: AustraliaPosts: 346 |
Yes you are missing something. The circuit posted below shows how the issues you raised above can be avoided. I have drawn the circuit to show the situation where the tank is empty and therefore SL is actuated by the weight of the bottle. When the timer switch closes (this will actually be a transistor) the relay operates via SL and when its contact B closes it will hold itself operated via B and SU. Contact A starts the pump, and when SL goes open due to the rising water, the relay remains operated because of the holding circuit. When the water level rises to the point where SU goes open, the relay releases the pump stops and when the tank empties, SL closes and if the timer is still active, the process repeats. If anything is unclear, just ask. Len 
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| larny Guru Joined: 31/10/2011 Location: AustraliaPosts: 346 |
A thought just occurred to me:- I didn’t cover your point about the water inflow versus outflow issue. I have assumed that the inflow will be much greater than the outflow. If not, then one solution would be to include a solenoid valve that stops the outflow until the tank is full. So me know if you need that option and I will modify the circuit to cater for it. The circuit that I posted in the previous post is what I had in mind when I wrote the description in the post on 8 June. Len |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
O.K. - I've had a good read of your June 8 Post again. For the intake/outtake, I originally thought faster in than out, but this really should not matter. The slower the time it takes to fill the Bucket/reservoir is the spacing between feeds E.G 4 hrs or whatever. So this is all about just emptying a tank and overriding a float switch (or 2 micro switches for those (or me) who want to attempt that)... pretty much. Timed circuit either way I think. If using a pump the other option is digital timer but forget that for now as I am leaning towards a different method at the moment. Solenoid ran off a float switch or pump off a float switch is what I recon you want for this setup to fully drain for the cycle. For others reading this and using a pump, only thing I suggest is a non submersible water pump, as once the water runs out of your area, your drying the pump out causing damage (because it is supposed to be SUBMERGED in water and you just drained the tank it sits in). Sure Larny would agree here. Easy to find pumps that can operate in a non submerged environment online. Other way is to make sure the drainage stops above your submerged pump, but this is just a longer way around I feel and does not interest me personally at the moment. Solenoid (gravity) would kick ass for this! O.K then, guess I would be asking for a circuit with a variable timer with say 3 time settings on it (to make it versatile and probably worth my while having a go at, as I could see myself making 2 or 3 of them for future add ons). Lets say I want the outlet to remain open/pump/solenoid release for 1 minute, 3 minutes and 5 minutes then cut off, overriding the off positions on float switches. These times are just guidelines. No big deal either if you can only make a timer circuit cycle 52 seconds or something just because that's how its design is. Even 2 settings would be a start I suppose. Open to suggestions for parts for this circuit design also... I'm flexible, and lets keep costs minimal and see whats out there that may do the job in a way that's easy and understandable for me, as I am just a basic solderer of kit style things. 
Over to you now Larny for input on the circuit layout. P.S Forgot to also add - I know the outlet will remain open and water may still continue to flow freely through the E.G. bucket, while this timer holds the solenoid open. This is what I want also. 
Cheers! This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| larny Guru Joined: 31/10/2011 Location: AustraliaPosts: 346 |
I really don't know what you want me to design. In the above post, you have suggested various possibilities. If the inflow is faster than the outflow, then the float switch would stop it when the tank is full. I don't know the pump flow rate nor the outflow rate. So I need you to tell me whether you need:- . a solenoid . a float switch . a timer like the Arlec one to start the process (I assume the answer to this question is yes) In short, I need an unambiguous specification. Something like this - for example:- 1. Start the pump at 7 am & let it run for 20 minutes. 2. Start the again pump at 3 pm & let it run for 30 minutes. 3. Start the again pump at 8 pm & let it run for 10 minutes. 4. If the tank fills, use a float switch to stop the pump. The times would be selectable of course, the above figures are just examples. |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
Nah nah nah, Its even simpler now.... By overriding the float switch, I basically mean this cycle.... 1.As the float levels out, from water rising in the E.G bucket, the switch turns on. 2.As the water drains from a solenoid opening to release water, the level drops, and the float would get to the off position. 3.Instead of turning off or closing the solenoid, I want the water to continue to drain past the floats off point, for a period of time E.G 2 minutes, 5 minutes or both. (So I guess I want the solenoid to remain open is what I am saying, for a period of time, with a variable/adjustable time control maybe if its not too tech for me to put together) 4.When the E.G 2 minute period of time passes, the device should refer back to the floats position, which would be in off position (as tank is now empty). 5.This then closes a solenoid, allowing the bucket to refill. End of Cycle - returning back to point 1. How the bucket fills up or where the water comes from is not a factor to consider. Ignore that. I have a another idea for that using a solar pump on a side pool. Not important in regards to this. I can explain it further but will just complicate things more at the moment. Whether it is a solenoid releasing the water or a pump removing it, I would want the same cycle to happen. Any more questions, yell out. This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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| larny Guru Joined: 31/10/2011 Location: AustraliaPosts: 346 |
I'll rephrase what you said above to see if I am understanding what you mean. 1. The water starts flowing from an external source that I don't need to consider. 2. The float switch closes when the tank is full. This operates the solenoid so the water starts flowing out & starts the timer. Question:- is the water still flowing in at this point? 3. When the timer expires after whatever period you set it to, the solenoid is released & so the circuit returns to state one. It is easy for me to design such a timer. Adjustable from say 2 minutes to 10 minutes - or whatever you choose. You should not have any problem in building it. But if there are any problems, you may need help. You said in one post that you have a friend who has electronics knowledge. So I expect he would be able to advise you on site. Of course, I can advise you via the forum, but it would be better & easier if you had someone looking over your shoulder. Comments:- I still don't know why you need the solenoid. If the outflow is faster than the inflow, then the tank will never fill. But if the outflow is slower than the inflow, you can simply use the float switch to stop the pump and start the timer. The cycle would re-start after the time period. The solenoid causes some complications, the ones I have for our watering system require 24 Volt AC. You were talking about a 12 Volt DC system. Even if your system is 24 volt, you would need to check whether the solenoid can be operated on DC. |
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| Lapsy Senior Member Joined: 28/01/2012 Location: AustraliaPosts: 103 |
OK - My response.... 1. The water starts flowing from an external source that I don't need to consider. Correct! 2. The float switch closes when the tank is full. This operates the solenoid so the water starts flowing out & starts the timer. Question:- is the water still flowing in at this point? Yep, water still flowing, although it is very slow (taking maybe 3-4hr to refill from the source you do not need to consider) and yes to the starting of the timer to keep the solenoid open for E.G 2 min say. 3. When the timer expires after whatever period you set it to, the solenoid is released & so the circuit returns to state one. Solenoid closes, yep. Bucket starts to fill again...... I have obtained a 12v solenoid that is working very nice connected to the float. 
One other random question for you though. What size hole did you drill to mount your float nice and water tight? This is my signature ---> Scribble, scrawl, a bit of light pencil shading, some indelable ink and a bit of caligraphy. |
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