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Beehive scale

Ivan901

Nov 29, 2015
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Hello. I am a beginner in electronics. I appologize if this is not the place for beginners, but i would really be thankful if someone would help me a little bit with a circuit design. I have placed a photoresistor as a sensor in cheap analog weight scale in order to get signals from the scale by an old mobile phone. I want to put the weight scale under the beehive. The led is above the scale indicator disc, and the photoresistor is beneath the indicator disc. There are holes on every 10kg mark which let the light go through when in right position. The photoresistor is hooked up to a key on phone keyboard, and it should call me since my number is set as a speed dial on a given key. The problem is, i need the signal to the keyboard only a few seconds, but when a LED flashes it, it stays for several hours or even days, and the phone would call me all the time. Weight is changing very slowly. I want something that will send a signal from a photoresistor to the keyboard for a few seconds. It should send a new signal to the keyboard only when the LED flashes it again, not before that. I know that I should learn some more first, and than start a project like this, but I really need this thing. It would be very useful to me since I have 100 beehives, and this device would be a real help. Sure, I have a expensive GSM scale, but a few of this cheap scales would be really great to have. Thanks in advance.
 

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davenn

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Sep 5, 2009
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hi there
welcome

your pics are way too small cant make out what they are
 

Ivan901

Nov 29, 2015
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My problem is to send a signal only a few seconds to the key of the phone. Othervise, the phone would keep ringing me again and again as long as the weight is unchanged. Also, i would like the phone to ring me when the photo sensor is lighted up again. Let's say, the weight is 70kg. Than the phone starts a speed dial. If the weight stays 70kg for 3 next days, i don't want it to call me during that time. If the weight drops to 69, and than goes up to 70 again, or if it goes to 80, i want it to call me than.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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OK, Ivan, if you can understand the technical details, great! If not, the actual purpose is to inform others. But please check the mechanical explanation!

My understanding is that Ivan is trying to be informed each time the hive changes significantly in weight. In order to do this, he has placed a light source and LDR either side of a disc with holes placed at appropriate intervals. The disc, being the dial on a set of scales means that an off to on transition is ideally a change of about 10kg.

The issue as I see it is that as the dial slowly rotates under changing load, the amount of light detected will slowly rise, then slowly fall, then slowly rise again as the next hole comes into alignment. Superimposed on this will be a rapidly varying signal caused by wind and/or vibration, and another signal caused by leaking ambient light.

The best way to remove any problem with ambient light is to ensure that no light gets in. It may be as simple as wrapping the scales in a thick black plastic bag (which should also protect the scales and electronics from the environment a little too)

The high frequency signals can be removed by a one or 2 stage RC filter. It matters little if the rise and fall time are extended since the change in weight is not expected to happen over a short interval.

Finally, the signal should be passed to a schmitt trigger with sufficient hysteresis to eliminate false triggering (CMOS 40106?). The next step is to detect only (say) rising edges, and to convert this to a fixed length pulse which can be used (somehow) to push the button on the mobile phone.

It is also vitally important that power remain connected permanently to the circuit. You mention how cold it is -- cold is death to batteries -- this may be an issue.
 

Ivan901

Nov 29, 2015
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Thank's for the reply. Now is under the hive without the phone and batteries, I will use the phone only in the summer. You helped me. I will change the design completely and make it more simple. I made it out of a photo resistor because i didn't wanted parts that will touch the scale indicator and disturb it. I will change the sensor to basic wire contats on the indicator. It is not meant to be precise in the first place. But even than, i have a problem. When a contact is made, it will stay on a long time, and the button on the phone will stay activated for all that time. I want only a signal to the phone for about 3 seconds, even if the contact stays on for 5 days. I reckon there is a simple solution for this which all of you know. If it's not simple, don't give me an exact solution, just if someone could point me in which direction to look at, which integrated circuits to investigate or something like that. I have some basic knowledge about DC current and electronics. I know about resistane, voltage, capacitance, inductivity, their relations and so on. I am a petroleum engineer so I am not a complete ignorant. I figure I could learn about electronics in future years. I am planing to read books on this matter in the future, but before that, I would like to make only a few of this scales. Once again, I apologize if I'm intruding the forum as a novice, this is simply the first forum about electronics that came out an my google search.
 

Alec_t

Jul 7, 2015
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If the weight drops to 69, and than goes up to 70 again, or if it goes to 80, i want it to call me than.
drilled holes on every 10kg
:confused: I don't see how you can get notification of a 1kg change if the holes are at 10kg intervals?
If you have 100 hives, will you want one of these gadgets at each hive? If so, you will need some way of sending a hive ID code.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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I think the key is that it moves significantly away from one of the measurement points and then back again.

That this is the desired behaviour is good because it would be very hard to provide a different behaviour.

I think a light beam is a better option than a mechanical option, but it will have a higher quiescent current drain.
 

Ivan901

Nov 29, 2015
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:confused: I don't see how you can get notification of a 1kg change if the holes are at 10kg intervals?
If you have 100 hives, will you want one of these gadgets at each hive? If so, you will need some way of sending a hive ID code.

I see you didn't understand me, but that's undarstandable since my explonation is rather confusing as I see now. I didn't want the scale to call me when it drops to 69, but when it returns to 70 from 69. But it doesen't matter. I will upload pictures or a video of it in the future days and I hope someone will have an idea how to improve it, it will be much clearer like that.
 

shrtrnd

Jan 15, 2010
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I'll throw-in my 2-cents worth.
I think Ivan's issue is that he believes he has a system that will work for him in measuring the weight of the beehive.
The issue is that I believe he wants to activate a phone when the weight changes. But only once when a specific weight it reached.
That could be done with a relay, maybe a time-delay-relay, set to activate the phone.
The issue THEN would be, after the relay resets, to not trip again until a new weight change is detected.
That's a more complex issue.
I'm not familiar with all these new arduino modules that can be used for specific applications, but maybe somebody knows of one that might work.
I think Ivan needs a relay to trip when a weight change occurs, then reset. Another circuit has to accept the new weight value and re-zero itself to that value.
Then when the weight changes again, the relay should trip again.
Might be off-base, but that's what I think he's saying.
 

GPG

Sep 18, 2015
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I can see this working as the weight increases but the scenario where the weight goes down and then up, is indistinguishable from up only. As for only sending for a short time a couple of 555 cmos will do it ( don't they always):)
 

Ivan901

Nov 29, 2015
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I'll throw-in my 2-cents worth.
I think Ivan's issue is that he believes he has a system that will work for him in measuring the weight of the beehive.
The issue is that I believe he wants to activate a phone when the weight changes. But only once when a specific weight it reached.
That could be done with a relay, maybe a time-delay-relay, set to activate the phone.
The issue THEN would be, after the relay resets, to not trip again until a new weight change is detected.
That's a more complex issue.
I'm not familiar with all these new arduino modules that can be used for specific applications, but maybe somebody knows of one that might work.
I think Ivan needs a relay to trip when a weight change occurs, then reset. Another circuit has to accept the new weight value and re-zero itself to that value.
Then when the weight changes again, the relay should trip again.
Might be off-base, but that's what I think he's saying.

Thanks, you got it. When it reaches the desired weight the thing would call me 100 times without stop until it drains the battery. I was thinking about getting the latching relay (two coils signal relay, keep relay, stay relay). The sensor would send a signal through the first coil and 555 timer or something, and in the same time, the switch in the relay would turn of the LED which is exciting the sensor. The timer would make a signal lasts for a few seconds. I would make a button on a scale to activate the other coil, which would switch the led back on, and the scale is back in action. That would do the purpose and it is satisfying since i need the scale for one call only. But it turned out that such a relay is hard to find, I can't find it in stores. I could import it, but i would rather not do that. Are there maybe some wide spread devices which use this relay from which i could take it? I am also thinking about building the relay on my own, it would be easy i think. Two coils, a nail and maybe little magnets to hold the nail when coils are not active. The coils would be much stronger than the magnets, so when the coil is active, it would pull it away from the little magnet and pin it to the opposite side little magnet, or something like that.
 

Ivan901

Nov 29, 2015
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I can see this working as the weight increases but the scenario where the weight goes down and then up, is indistinguishable from up only. As for only sending for a short time a couple of 555 cmos will do it ( don't they always):)

I know that i could not distinguish if the scale is going up or down, i was just giving an example. The point was that I didn't want the scale to call me several times while on the same weight. The scale, in reality would not go down. I would use it as a "beehive scout". For example, I would place the hives with scales on different locations, let's say a few large sunflover fields would be "scouted" by the scales. They would help me decide when to move the rest of the hives and which location to pick. There are sorts of sunflover which does mot produce nectar at all, so its a thing to avoid. The sunflover fields are, here, often treated with illegal poisons which are deadly for bees so it can help me avoid that to. For example, if the hive weight is 31kg, I would put bricks on the hive to make it's weight 37kg. So, when the weight goes up to 40, it would call me and it would be a valuable information. It is highly unlikely for a hive to lose weight 7kg and go back to 30kg. They can't consume that much honey for a short time, and there is about 5 kg of bees in the hive, so even if they all die suddenly (never happened to me), it would still not go 7kg down. I already have something like the thing in the picture I attached. I use it for fine measurement. It would be very stupid of my to buy several of those things. They cost about 400 dollars a piece, so i would need to pay about 1600 dollars for 4 pieces. Not to mention the possibility of the thing being stolen. And I totally don't need accurate measurement on the other scales, one is enough. Plus, even the accuracy of the expensive scale is doubtable. I have some new ideas how to improve the cheap scale, but I will built the simple one first. I have an idea how to detect accurately each kg. The information (number of kg) will be transferred to the microcontroller, which will instruct the old nokia phone (via fbus cable) to type me an sms with the number of kilos on the scale. I could even attach several hives to the microcontroller and monitor them too with the same phone. I will try to do the microcontroller and the phone part on my own in the next weeks and months, there are many books and instructions online on that matter. But if get stuck, i will find someone to help me, so i think it is doable.
 

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shrtrnd

Jan 15, 2010
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You're talking a microcontroller, so you should be able to Google information that will help you set the microcontroller up for specific functions.
Your initial issue I believe, can be solved with a TDR (time-delay relay).
When the trip weight is reached, the relay latches for however many seconds or minutes you set it for (you buy the relay with the time interval you want, many are adjustable).
The latched, or closed relay contacts can send your circuit signal to your phone interface.
The time delay relay maintains the contact circuit for the time interval you set it for, and then automatically resets itself, ready for the next relay-trip set point. Which could be
selected by your microcontroller.
The reason I suggest using the TDR, is that as you mentioned, you don't want to lose a lot of money if theft occurs.
A programmable logic controller would do everything for you, but you wouldn't want somebody to steal it. A TDR is less costly.
We hope the best for you with this project. When you get further along with your plan, people here will be happy to help provide information
for more specific questions about implementation that you might have. Good luck
 

duke37

Jan 9, 2011
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I would measure the weight of the hive each midnight when the bees are all tucked up in bed. You could make your own scales with a spring and potentiometer. If a tone was generated, a micro at base could translate this to weight.
 
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