When I was a kid, there was a rat on the porch that used the dog door. It was huge. Our yard was between a guys shed and a wood pile at the other neighbors.

We also had either small rats, mice or voles which I would flood out of their homes and the dog would have some fun,

 

Rarely but on occasion I've seen a rat. Most recent was a mouse the size of a walnut. Scooped him up with a gloved hand. Was cute how he tried to act so mighty in the hopes of scaring me off. Actually I saved him from my cat. Released him unharmed in the neighboring woodlands.

We have a much bigger problem with ferrel cats. They come around and spray. One day I will build a PIR with a washing machine water solenoid and a spray rig to give them a good dowsing with water. Several years ago I tried baiting them with food in a metal dish on an insulator over a wire mesh. The bowl and mesh were hooked up to a cheap Harbor Freight electric fly swatter. It will give then a snap in the nose and they go running. I have film of a couple cats going for the free food only to be sent galloping away full speed. They learn to avoid free food but still come around and spray. And that bugs the heck out of my cat. She'll go running from the living room window to the back slider with her fur all poof'd out.

 

There are plenty of deer in the area, but the highway usually filters out most of the intrusions. Then what doesn't get them on the highway usually gets them on main street. But in the 14 years I've been here I haven't seen a carcass on the main drag, which is adjacent to the highway.

 

Thank you vu2nan for your plan, it's a bit out of my depth but I could give it a go

Anytime!

The 'set' button triggers a relay and, along with the solenoid, gets isolated from it when the 'NC' contact opens.

The 'NO' contact keeps the relay and LED on, till the 'reset' button is pressed.

If required, a bigger 240 V lamp may be lit as shown below.



Nandu.

 

What you decide on, depends somewhat on how your trap works.

Cost depends on how much effort you want to put into it. Industrial controls are based on 24 VDC power. DUN rail provides an "erector set" for all sorts of parts that get wired with big wires.

You could have a light loaded board that has the switch and the switch activates the solenoid closing the door. There may or not be the problem of the solenoid continuously being on. In this case you can reduce the problem to "pulseing the solenoid" and "detect door position". In this case, no latching relay is required.

 

Thank you all so much for your help and advice, I now have plenty of ideas and information to go on.
Rats, look out, there's a boot on the end of my leg with your names on it..
I hate killing them, but as long as I can stamp on their head and put their lights out as quick as possible, then I can live with that.

 

My boss set up a few "walk the plank" mice traps. A garbage pail with a plastic liner. A ruler hanging off the desk with a piece of peanut butter at the end.

 

I once set up a similar trap using a trash pail with a few inches of water so mice could not jump out. On top of the pail was a plastic sheet that would fold down when enough weight was present but snap back up after the sucker fell into the water.

Every night this trap would catch mice. First night I think I caught about 20 mice. The numbers dwindled somewhat but they never dropped below six souls. Each morning the trap was emptied on the other side of the creek. I'm opposed to killing unnecessarily. Then again, rats (or their fleas) can carry disease. Still, they essentially perform a service of cleaning up decaying bodies, be they bugs, other rodents, animals struck by cars or heum - - - um - - - never mind.

 

Around here, the rats came from elsewhere as urban renewal and new construction chased them out. Rusted through dumpsters and plastic garbage bags keep them fed well enough to prosper. and some folks campaign against poisoning them because some other animal might eat the dead rat and be poisoned, or some cute but destructive chipmunk or squirrel might eat the poison. So the rats tend to prosper. A shovel works at least as well as a boot, and can not be damaged by being bitten. I was going to discuss electronic rat zappers, but that is not allowed on this site.

 

Well, the mice made a big nest in the car. Chewed 3 spark plug wires and the wires to am MAP sensor. Surprisingly, the engine still ran. it sounded "funny", so I opened the hood in the dark and saw nicely timed sparks across the bitten wires.

They found a way inside the porch. In it's early days, it was a patio where the gutter emptied into PCV pipe burried into the cement, There was a sink installed on the porch that would be used to fill the dogs water or wash vegtables. The sink emptied into where the gutter emptied with no real seals or trap. So, mice were found inside the porch too. I fixed the hole with a Stainless screen.

A few weeks after the mice were evicted from the engine compartment, the squirrels moved in.

The squirrels are always sharpening their teeth on something like the ridge vent and metal siding. I've heard stories where they can cut the 1/8" Aluminum ties that hold up a cyclone fence. Usually, they are pretty well behaved.

Now, I don't like carpenter bees. The ones that chase, can't sting, but they can put up a chase. Eviction is a bit harder.

Something did some damage this summer and I don't know what. Could be bees. Could be termites, Never saw them active,

Birds made a nest in the porch. Upper part of window open about 1-1.5". They hatched, but could not get out,

 

For those of you with Facebook accounts, search for the user Mensajes

She has posted many different trap designs and demonstrates them catching hundreds of the little creatures.

https://www.facebook.com/1600375290032825/posts/4617762781627379

 

Assuming that you have a low V PS, a low power SCR , 2N5060 ?, can latch the LED.

My guess is that 95% of the people who read the problem description (including me) thought of a 555 at some point. But why use an 8-pin device when a 3-pin will work just fine.

* * * *

ak

 

I like Tony's idea with the microswitch, using the trap door as the toggle flipflop. Nice.

If you have a spare wall wart of just about *any* kind laying around, it will replace the transformer, bridge, and capacitor.

ak

 

use a pre-built module. Like this.

Nice find.

ak

 

Latching relay?

 

My guess is that 95% of the people who read the problem description (including me) thought of a 555 at some point. But why use an 8-pin device when a 3-pin will work just fine.

* * * *

ak

Well, why use a 3 pin device (often with many unused pins) when a simple switch will solve the problem entirely?

 

Well, why use a 3 pin device (often with many unused pins) when a simple switch will solve the problem entirely?

I agree - #33.

ak

 

Back in post #7 a latching relay was suggested. Either a mechanical latching relay or a bipolar coil type would work. Even an electriical latching arrangement would work and has been suggested.

 

The advantage of magnetic latching relay is that power glitches won;t affect it's state.

The trap might not work if you don't have power, in which case you can set another DPDT normal relay to detect a power failure.
One N contact powers the coil. It has a momentary NO push button across it. You push the button to set the relay. When the relay looses power the NO contact that was forced closed drops out.

 

The second advantage of some sort of mechanical relay is that it is far more forgiving of electrical spikes and static electricity sparks. And even quite a few incorrect connections. Besides that, on many of them it is possible to see just what is actually happening as the circuit functions. And, in some cases, itis possible to discern what the connections would be even if there is no illustration of how to connect to it. So there are quite a few advantages for the beginner, as well.