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How to time a little door so it opens at a certain time? (no need to close)? Answered

I want to build an automatic cricket feeder for my lizard (bearded dragon) because I have to stay home at her eating times and sometimes I want or need to go out.

* Ideally I would like to build a small "cabinet" with 1-3 drawers and somehow make the doors open at 11am, 4pm and 9pm,
* If this is too hard one door will do but I would need to reprogram it constantly. (crickets would be inside and they would get out as soon as the door opens)
* I already have a timer that I can plug and program to 23 different times so I was thinking on using that (or not), It could be something that when on opens or keeps the door open, and I can keep it off the rest of the day with the timer, I just don't know how to do this and how to do something that won't burn after a minute on because that's the minimum time the timer works.
* It doesn't need to close back (and that is safer too)
* It can't be light activated because some lights are on at all times and another has a timer and goes on for 20 minutes every hour.
*It needs to be small because the terrarium is 18inchX18X18 and I don't want to take a lot of room

Thank you so very much!!


There are literally thousands of ways to go about this...

As Rube Goldberg as iceng's suggestion; a mechanical timer would do the job quite well.

Rick has a good feeder, and since it moves very slowly won't harm the crickets.

I like the idea of the trapdoors on the bottom -- a compartmental box with lids on the top and bottom that you can put a few in each compartment, using a slow gear motor or timed motor, you could slowly retract a rod from underneath all the doors to expose them one at a time.

A micro-controller solution is overkill but is a great project where custom timers are important. It's a great educational project.

Remember, per the zero'th law, if you make it you have to post it!!!

Thank you for the compliment,  I have always really enjoyed Rube Goldberg.
His style must be rubbing on to me :-D


get a real clock and put a piece of paper on the hour hand. embed it into a holder with 3 LEDs at the hours you want opposite a light sensor, when the hour hand blocks the light the electromagnet holding the door closed turns off and the crickets drop out.

Thank you very much for your answer, but I don't have an electromagnet holding the door, I don't even have the door... =(

That is what I want to know how to make, now I know I need to figure out how to have an electromagnet holding the door-to-be closed.

thank you!

Friction or a snap lock.

Does you monster NEED to be fed 3 times a day?

However in industry something like this might be used.

The vanes revolve slowly releasing the food periodically depending on how fast they revolve.


6 years ago

Is an alarm clock, a string, a cork and a tube tooo much for you.

Wind the alarm to pull a cork out of a cricket tube when the mechanical alarm
rings and winds the string on the key pulling the cork out.

It could pull a drawer too.


alternatively just buy 3 xmas light timers they are cheap, and have them turn ON to open the doors whenever.