Hello,

I'm an English Teacher by trade and not well versed in electronics or circuitry. I'm building a prop for an interactive puzzle in my classroom.

My first project involves a second-hand wooden file cabinet. The file cabinet had a key lock on the top drawer that I replaced with a keypad and drawer latch kit (pre-fab). The bottom drawer used to lock with a verticle rod along the inside panel that when in the up position would engage a catch on the side of the bottom drawer, thus locking it. With the removal of the original key lock mechanism I rendered the vertical rod locking mechanism useless on the bottom drawer; however, I see mechanically, with the use of a solenoid I could make it operational again.

What I want to do is affix the solenoid to the inside panel of the file cabinet and have it wired to a button in the top drawer. I have a 12-volt power supply (8AA x for 12-volt found on Amazon), a 12-volt solenoid, and a 16mm, 12v angel eye button. I am very new to building circuits, so I am unsure if I need anything else to put this together? Any help would be appreciated.

Thanks,
Steve

 

The solenoid would need to be powered to hold it in the locked condition. (Or the unlocked condition if the mechanical was arranger the other way round.) This would drain the battery fairly quickly. You may be better off using a small motor driving a threaded rod. A model servo could be another possible soulution.

Les.

 

I was planning on having the solenoid hold the vertical rod upright or locked position when the solenoid was not energized and when the button is pressed it retracts the arm of the solenoid allowing the vertical rod to drop (via gravity) and unlock the bottom drawer. I think with that set up it will not put an undue drain on the batteries. I will definitely research the small motor driving a threaded rod to see if that works better for my application.

Thanks Les!

 

I had missunderstood how you wanted it to work. I thought it was going to behave in the same way as the key lock and left in the unlocked condition for a reasonable time while it was being used. The solenoid is probably the simplest solution for the way you intend it to work.

Les.

 

I'm building a prop for an interactive puzzle in my classroom.

We need more teachers like you who motivate getting the students to think. Interactive is a "good thing".

Depending on the solenoid and how you configure it your battery pack may or may not suffice. Solenoids are labeled with force (how much force they are capable of) and the throw (how much travel you get). Play around with it and see what you get would be my starter advice. Then if you have problems just ask.

Ron

 

Perhaps I missed something.

What is the goal of the project? Specifically, what is the "interactive puzzle" that you are trying to achieve?

Another alternative is to have the solenoid be the type that pushes or pulls depending on polarity of current but that does neither with no current. Then you could use a simple overcenter mechanism that your button(s) move from one position to the other but that draw no current except when making the transition.

 

The Interactive Breakout EDU puzzles day in my class are the conclusion of several week units that we teach students concepts on a theme. The previous one I and my colleague did was a three week unit on infectious diseases (Measles, Bubonic Plague, Ebola, CDC, WHO, etc.) We showed the film Contagion and made a film guide in addition to many related news articles and question sheets. We took much of the learning and built a Zombie themed Breakout EDU puzzle for the final day. The students really enjoyed it and we wanted to up our game by adding electromechanical puzzles into the mix.

We are considering either a Travel to Mars unit or Cold War unit for the next one. The first electromechanical puzzle I am attempting to build is the 2 drawer file cabinet. For this puzzle, it will be two staged. The students will have to solve a puzzle (based on some curriculum yet to be developed) that will give them the 5 digit combination to unlock the top drawer. The will naturally expect the bottom drawer to unlock too, but it will not until the button is pressed that activates the solenoid to allow the vertical rod to gravity drop an inch to the unlocked position at which point they can open the bottom drawer. The bottom drawer will then hold instructions for the next step or next clue. I am planning to hide the button under a false bottom in the top drawer or camouflage in some way.

 

We need more teachers like you who motivate getting the students to think. Interactive is a "good thing".

Depending on the solenoid and how you configure it your battery pack may or may not suffice. Solenoids are labeled with force (how much force they are capable of) and the throw (how much travel you get). Play around with it and see what you get would be my starter advice. Then if you have problems just ask.

Ron

Thank you for the compliment regarding making my class more interactive. I've found that by making learning fun, you really have success with students.

 

If the solenoid doesn't work out, consider an automotive door lock mechanism. These are available on the surplus market. As mentioned above, it is a small 12 V DC motor driving a push/pull rod with a hole in the end to attach stuff.

I pressed the post #7 Like button six times.

ak

 

Thank you for the like button on the thread and the tip on the automotive door lock mechanism. That may work better than a solenoid.

Steve

 

'door lock actuator' on ebay returns many.
https://www.parts-express.com/high-power-door-lock-actuator-2-wire--330-010
https://www.banggood.com/12V-Car-Au...vy-Duty-Power-Door-Lock-Actuator-p-85192.html

Note that these do not spring-return. You drive the motor with 12 V of one polarity to extend, and the opposite polarity to retract. Most have internal limit switches to prevent over-travel.

ak

 

Thanks for the product recommendations. I figure some photos will help clarify my project situation. Here is the website link to the project elements. https://sites.google.com/egusd.net/breakout-edu-project-photos/home

In the third photo, I have a cabinet latch where the solenoid will go as a placeholder. The last three photos are the 8xAA batteries for 12v, the 16mm 5 pin Angel eye 12v button and the 3v-12v DC 80mA-350mA micro solenoid. I'm wondering if I'm good to just wire them up or am I missing necessary components?

Thanks,

Steve
https://www.facebook.com/profile.php?id=100009069855409

 

Start with a wiring diagram so you (and we) know how all of the pieces interact.
Are you sure the solenoid has enough pulling force and travel?

ak

 

Start with a wiring diagram so you (and we) know how all of the pieces interact.
Are you sure the solenoid has enough pulling force and travel?

ak

Thanks for the advice. I will work on a wiring diagram. I'm not sure it has enough pull force, but I feel confident that it has enough travel room to disengage the verticle lock bar.