One idea that comes to mind: Using the RC car as a reciever, hack a solenoid where the motor is supposed to go, and put a diode on it to only respond one way (RC car motors reverse). When the solenoid fires, it releases a catch. Seems like a lot of stuff just to fire a solenoid, OTOH, you can go buy the whole kit at Radio Shack for a few bucks, and the hapless (PICless)Ornithologist can build it himself so I don't have to. What other off-the-shelf stuff is radio controlled and dirt cheap? Isn't there a radio-controlled motor that comes with those "Mecanno" erector sets? --Lawrence (Who thinks you can never have enough erector sets " in case your nephew comes over") ----- Original Message ----- From: "Hazelwood Lyle" To: Sent: Monday, June 24, 2002 12:59 PM Subject: Re: [EE]: Hummingbird trap I am no expert on ornithology, or even birds for that matter. 8^) My first thought would be to use a servo or solenoid to pull a latch pin, and allow gravity or a spring to close the door. The advantage is that you are less concerned with powering the entire travel of the door. of course, you'd have to be careful with the spring tension, else you may only have half a hummer left in the cage. The Other Lyle -----Original Message----- From: Lawrence Lile [mailto:llile@TOASTMASTER.COM] Sent: Monday, June 24, 2002 1:27 PM To: PICLIST@MITVMA.MIT.EDU Subject: [EE]: Hummingbird trap A friend of mine is a biologist, a professional ornithologist. (My cat is also an ornothologist, an avocation I have tried to stop for quite a while as she leaves them on the front porch). He studies hummingbirds, and is looking to make a trap for them. He has a little hummingbird feeder built into a special cage with a trapdoor for catching hummingbirds. Now he doesn't just want to catch any hummingbird, he wants to watch the cage, and when a specific hummingbird comes to feed, he wants to actuate the trapdoor remotely and catch them. I think he bands thier legs, weighs them, takes blood samples, eats them for lunch, I don't know. How he tells them apart who knows ( maybe he asks for a picture ID ). I guess he is looking for rare, unbanded, or birds of a particular gender and so on. He has several traps all used at the same time, so another part of the challenge is to have several traps on different frequencies or signals so each trap can be fired individually. He has tried to make a badly hacked system that is cobbled out of a model RC car which hasn't really worked yet. He punches the button on the RC car control, and a wheel turns on the toy truck held to the bottom of the cage by a bunch of rubber bands, unwinding a string which holds up the trapdoor. There is probably a midget captain, a candle burning through a piece of string, a rolling bowling ball and a rabbit in the contraption somewhere, as well. The toy car only has reverse and forward modes, no stop, so it winds the string into a knot at the end of a trap cycle. The big problem is, hummingbirds are fast. His toy car can lower the trapdoor in several seconds, and by then the wary hummingbird is long gone. What he'd like is a radio controlled remote system that releases the trapdoor instantly. He's also like it to be cheap to build and not require too much expertise to construct. The challenge is probably to hack this out of some commercial product or other with a couple of extra parts and not much programming. A little soldering is OK. A few extra solenoids would not be a problem. It is easy to think of a way to do this with fancy microcontrollers and such. Keeping it simple is a little harder. How about RC model airplane controls and servos? I have messed around with servos driving them directly with PICs, but never messed around with the RC controls that are really meant to run them. Could a simple-to-build system be built with this stuff, and at what kind of cost? Could a servo be arranged to drop a trapdoor fast? How fast can a servo operate, is well under a second from stop-to-stop achievable in a small servo? --Lawrence -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body