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Post by cjm on Dec 18, 2018 19:38:27 GMT
Generally I would not have bothered with this post. Designs for these circuits are not so common on the internet though and they are quite useful if one uses a relay to switch something, in place of the load. The chip can handle 200 mA max on the Output/Load side.
I intend using it in a simple alarm. There are many applications such as a fridge door alarm or the interior lights of a car.
The delay can be changed by fiddling around with the sizes of the capacitor and 47k ohm resistor.
I have built it. It works.
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Post by cjm on Dec 26, 2018 19:45:39 GMT
While the circuit worked fine with a 9v battery (and a 12 V one) , I needed it to be connected to a more permanent power source.
I tried various transformers without success. Eventually, I came to suspect that the output of the various sources (including those used for charging cell phones and other gadgets) was delivering a crude 12 V DC not liked by the IC.
This resulted in a search for power source circuits. I built one and the timer now works via a transformer off the mains.
The basic diagram looks as follows ( link) :
In my own effort, transformer (T1) turns 220 V AC into 16 V AC . In place of C1 I use a 2200 micro F and next to the C1 I have a parallel C2 circuit with a 0.33 micro F capacitor. The reason for the latter is that this is what is required by the data sheet illustrated below ( link ):
My C1 is in addition to these two capacitors and I also used a C3 of 0.1 micro F as suggested by the data sheet.
The two links I have provided, give much more information.
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Post by Trog on Dec 27, 2018 6:11:48 GMT
While the circuit worked fine with a 9v battery (and a 12 V one) , I needed it to be connected to a more permanent power source.
I tried various transformers without success. Eventually, I came to suspect that the output of the various sources (including those used for charging cell phones and other gadgets) was delivering a crude 12 V DC not liked by the IC.
This resulted in a search for power source circuits. I built one and the timer now works via a transformer off the mains. I hesitate to comment on this. Electronics is a very recent interest of mine. But I've found the LM317T to be very useful. You can set its output voltage to whatever you want with the use of 2 resistors. You can then input in any voltage, and it will output the required voltage. E.g. if you set it up to deliver 3.3V, you can hook it up to 6V, 9V, 12V, whatever (within limits) and it will deliver a constant 3.3V. The way I understand it: If you want a constant power supply, a battery charger is not a good idea, because a battery charger is specifically designed to vary its output voltage in response to the stage of charge of the battery it is connected to. It is therefore inherently not a constant power source. |
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Post by Trog on Dec 27, 2018 6:22:48 GMT
I hesitate to comment on this. Electronics is a very recent interest of mine. But I've found the LM317T to be very useful. You can set its output voltage to whatever you want with the use of 2 resistors. You can then input in any voltage, and it will output the required voltage. E.g. if you set it up to deliver 3.3V, you can hook it up to 6V, 9V, 12V, whatever (within limits) and it will deliver a constant 3.3V. The way I understand it: If you want a constant power supply, a battery charger is not a good idea, because a battery charger is specifically designed to vary its output voltage in response to the stage of charge of the battery it is connected to. It is therefore inherently not a constant power source. Okay, I see that the 78XX IC in your circuit is also a voltage regulator, similar to the LM317, although not adjustable as in the case of the LM317. |
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Post by cjm on Dec 27, 2018 6:34:25 GMT
I hesitate to comment on this. Electronics is a very recent interest of mine. LOL
I don't pretend to know ANYTHING!! It is an interest (with matric science as a back-up!) *blush*.
If you are fearful of commenting, I should not open my mouth!!
Thanks for the info about the LM317T (in fact, I remember now that I have one in one of the PC boards I strip for parts). I came across various diagrams for changing the Voltage, but I did not need it, so I took no further interest (saving a few brain cells in the process).
What I illustrated dramatically is that the many chargers and even a concocted rectified transformer, are not suitable. It took me a loooong time to figure out what the problem was *blush*. The word "dramatically" is used advisedly as I blew up 2 x 555, my multimeter and a transformer in the process!!!
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Post by Trog on Dec 27, 2018 7:51:00 GMT
Hmm. Transformers can be dangerous things.
I've been walking around with this idea to build a rat-killing device.
The design is as follows:
Use some 12V battery power-source. Dry cells, if necessary.
Connect it to some sort of MOSFET H-Bridge.
Get a 555 timer to switch the H-Bridge at 50Hz. (50Hz, because most of-the-shelf transformers are designed to operate at 50Hz1).
Stick a large capacitor over the output of the H-bridge. You should then have something very similar to a sinusoidal 12V AC.
Feed the output into the low end of a 220V-12V transformer. (Sourced from some defunct home appliance).
You should then have 220V over the high end of the transformer. I.e. you have essentially constructed an inverter.
Now, feed this 220V into a microwave 220V-2000V transformer. These transformers typically have a voltage-doubler capacitor attached, so that you will have 4000V available.
Now, feed this 4000V into a bank of huge parallel connected high-voltage capacitors, until they are fully charged to 4000V.
Switch off the charging circuit.
The capacitors are connected to two strips of copper sheet, placed flat on some surface, with about a 1cm strip between them. Some means are devised to make it attractive for rats to explore this environment.
When parts of the rat straddle the strip between the plates, about 4000V will pass through the rat, for several minutes. The rat will be dead.
All of this will be part of a device, which at this stage will have the means to remove the rat and to restart the charging circuit.
So this is the plan. I do hesitate somewhat, though. My main concern is with the capacitor bank charged up to 4000V. I imagine that one would need to think very carefully about what you are doing while experimenting with this. Otherwise I suspect that there exists a distinct possibility of killing the biggest rat of all.
(1) Transformers are designed for optimal operation at a given frequency for a particular wave form. So that, whereas transformers designed for a 50Hz sinusoidal current will work with something else, i.e. a 200Hz square-wave current, it will hum or sing, and lose a lot of energy to heat.
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Post by cjm on Dec 27, 2018 8:22:40 GMT
Hmm. Transformers can be dangerous things. I've been walking around with this idea to build a rat-killing device. The design is as follows: Use some 12V battery power-source. Dry cells, if necessary. Connect it to some sort of MOSFET H-Bridge. Get a 555 timer to switch the H-Bridge at 50Hz. (50Hz, because most of-the-shelf transformers are designed to operate at 50Hz 1). Stick a large capacitor over the output of the H-bridge. You should then have something very similar to a sinusoidal 12V AC. Feed the output into the low end of a 220V-12V transformer. (Sourced from some defunct home appliance). You should then have 220V over the high end of the transformer. I.e. you have essentially constructed an inverter. Now, feed this 220V into a microwave 220V-2000V transformer. These transformers typically have a voltage-doubler capacitor attached, so that you will have 4000V available. Now, feed this 4000V into a bank of huge parallel connected high-voltage capacitors, until they are fully charged to 4000V. Switch off the charging circuit. The capacitors are connected to two strips of copper sheet, placed flat on some surface, with about a 1cm strip between them. Some means are devised to make it attractive for rats to explore this environment. When parts of the rat straddle the strip between the plates, about 4000V will pass through the rat, for several minutes. The rat will be dead. All of this will be part of a device, which at this stage will have the means to remove the rat and to restart the charging circuit. So this is the plan. I do hesitate somewhat, though. My main concern is with the capacitor bank charged up to 4000V. I imagine that one would need to think very carefully about what you are doing while experimenting with this. Otherwise I suspect that there exists a distinct possibility of killing the biggest rat of all. (1) Transformers are designed for optimal operation at a given frequency for a particular wave form. So that, whereas transformers designed for a 50Hz sinusoidal current will work with something else, i.e. a 200Hz square-wave current, it will hum or sing, and lose a lot of energy to heat. Seems like you have problems with rats! There are some very effective rat poisons.
Some very clever ideas in that design though - eg using dry cell batteries and loading the capacitors like a single bullet. One gets inexpensive rubber rat traps where the rat enters a poison station protecting pets and the like . Perhaps you can put the copper strips inside?
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Post by Trog on Dec 27, 2018 9:30:35 GMT
Seems like you have problems with rats! There are some very effective rat poisons. Some very clever ideas in that design though - eg using dry cell batteries and loading the capacitors like a single bullet. One gets inexpensive rubber rat traps where the rat enters a poison station protecting pets and the like . Perhaps you can put the copper strips inside?
There are devices like these available: Victor Electronic Rat TrapThe problems I have with them: - They can kill only one rat at a time. You have to remove the dead rat before it can be reused.
- I perceive a measure of arbitrariness in the way the rat is positioned with regard to the electrodes.
- I doubt that the voltage used is that high. Rats can survive shocks of 220V by restarting their hearts.
But I see something similar but more elaborate, to compensate for the above. The thing could even send you a WhatsApp everytime it kills a rat. I'm not too fond of poisons. I do use them, but I worry about what they would do to owls and other indigenous wildlife and pets who gobble up rats confused with poison. |
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Post by cjm on Dec 27, 2018 11:28:04 GMT
Seems like you have problems with rats! There are some very effective rat poisons. Some very clever ideas in that design though - eg using dry cell batteries and loading the capacitors like a single bullet. One gets inexpensive rubber rat traps where the rat enters a poison station protecting pets and the like . Perhaps you can put the copper strips inside?
There are devices like these available: Victor Electronic Rat TrapThe problems I have with them: - They can kill only one rat at a time. You have to remove the dead rat before it can be reused.
- I perceive a measure of arbitrariness in the way the rat is positioned with regard to the electrodes.
- I doubt that the voltage used is that high. Rats can survive shocks of 220V by restarting their hearts.
But I see something similar but more elaborate, to compensate for the above. The thing could even send you a WhatsApp everytime it kills a rat. I'm not too fond of poisons. I do use them, but I worry about what they would do to owls and other indigenous wildlife and pets who gobble up rats confused with poison. I agree about the poison. Some of the products congeal the blood of the target and are not as environmentally dangerous (I think, although I wonder about a pet eating the rat). Having the dead rat inside the container is perhaps not so bad. At least it is not hidden in an obscure crevice where it stinks to high heavens for months! It is also kept away from pets and wild life.
I wonder whether with 4000 volts it would not be sufficient merely to ground the floor of the enclosure and have the other terminal connected to a metal eating bowl. Here is an example of some of the available bait stations which one could perhaps convert
How on earth do you know about rats and electrical shock?! |
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Post by Trog on Dec 28, 2018 9:43:02 GMT
I wonder whether with 4000 volts it would not be sufficient merely to ground the floor of the enclosure and have the other terminal connected to a metal eating bowl. The thing is, if the rat touches the eating bowl, it will get a jolt and will almost certainly jump, which will break the electrical connection. Most other arrangements will have a similar effect. One needs to find an arrangement to position the rat's body so that even fairly large movements will still maintain an electrical connection. That is why the electronic devices invariably have a narrow, tunnel-like shape. I think that this is sub-optimal and have other drawbacks as well, in that rats will tend to avoid entering it. I suppose they will work adequately if you are prepared to put them down somewhere and don't mind waiting for a while to get results. Following on my comment above: Rats are profoundly suspicious creatures and will avoid anything in their environment which they are not familiar with. From some videos I've watched, they seem to be particularly averse to crawling into confined spaces, particularly if it is into an area that is visually cut off from their overall surroundings. For such structures, they will spend days or weeks getting used to it, do a quick peek inside and running away, etc. before they will venture to go inside. Whereas they are much happier to investigate something that does not present as an enclosing structure. Or something that does not impair the visual connection with their surroundings - such as a wire frame. I read up on this fairly comprehensively, a while back. |
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Post by cjm on Dec 29, 2018 5:31:22 GMT
I wonder whether with 4000 volts it would not be sufficient merely to ground the floor of the enclosure and have the other terminal connected to a metal eating bowl. The thing is, if the rat touches the eating bowl, it will get a jolt and will almost certainly jump, which will break the electrical connection. Most other arrangements will have a similar effect. One needs to find an arrangement to position the rat's body so that even fairly large movements will still maintain an electrical connection. That is why the electronic devices invariably have a narrow, tunnel-like shape. I think that this is sub-optimal and have other drawbacks as well, in that rats will tend to avoid entering it. I suppose they will work adequately if you are prepared to put them down somewhere and don't mind waiting for a while to get results. Following on my comment above: Rats are profoundly suspicious creatures and will avoid anything in their environment which they are not familiar with. From some videos I've watched, they seem to be particularly averse to crawling into confined spaces, particularly if it is into an area that is visually cut off from their overall surroundings. For such structures, they will spend days or weeks getting used to it, do a quick peek inside and running away, etc. before they will venture to go inside. Whereas they are much happier to investigate something that does not present as an enclosing structure. Or something that does not impair the visual connection with their surroundings - such as a wire frame. I read up on this fairly comprehensively, a while back.
Seems like there is something to say in favour of the good old spring loaded mouse trap!
Looking at all your design parameters, it seems that some mechanical interventions are inevitable: At least something to restrict rat movement for a few seconds. The container itself could perhaps be made of plexiglass (or similar), to give the rat a sense of space. Inside one could have an electrified wire roof falling onto the rat once the trap is triggered. It could at the same time prevent escape back through the entrance.
I thought of a wire cage, but plexiglass/perspex would be safer from a safety point of view. One could drill it full of holes as well to enhance the safe space effect!
As you probably know, sms sender units are available at low cost which could easily be employed to send notifications when the trap is triggered.
The bait stations are widely employed in food outlets/ food processing plants where hygiene is an issue and to prevent food contamination by the bait. In fact, I have a suspicion that they are often mandatory. An effective electrical trap would be sought after for use in these establishments.
We often use the coagulant in open feeding bowls in outbuildings and the like. That is very effective. You are right, the bait stations seem to be less effective.
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