Customer:
I’m building circuits for an escape room and need help selecting components and understanding how to wire them. I’ve got four puzzles:
1. Chess Table
Players find 4 chess pieces and place them in correct positions on a board. When all 4 are in place, a magnetic drawer lock should open. I’m planning to use reed switches under each position with magnets on the pieces, wired in series. When all 4 activate, the lock opens. I need a complete components list and circuit diagram.
2. Fireplace
Players place an item on a fake fire. When they do, a door pops open. I want to use a reed switch and magnetic lock, plus play a 30-second sound and light up an LED strip. I need components list and circuit diagram.
3. Weirwood Tree
Players find two eyes and place them on a tree face. When both are in place, the mouth pops open. I’d prefer not to use more reed switches - could a light sensor work in a dark environment? I need components list and circuit diagram. What sensor would you recommend?
4. Dragon Hearth
Players pinch a liquid-filled hearth. This should activate a mechanism that lights up after 5-10 seconds. I’m considering a push button triggered by the squeeze action, but I’m worried about accuracy. I need components list and circuit diagram.
I also need cables, individual boards for each circuit (they’re in different locations), and advice on other materials like wires. Do you stock reed switches? If not, where should I order them?
Originally submitted via email support on 14 March 2016. Migrated to the forum for community visibility.
Soldered Support:
Chess Table
Since any figure with a magnet will activate any reed switch, any piece can go in any position and the lock will still open - if that’s acceptable, connect the four reed switches in series. One end goes to +5V of a Croduino, the other end to a digital pin where you’ll read their state with digitalRead().
Components needed:
- Croduino (Arduino-compatible board)
- 4 reed switches (or hall effect sensors, which activate when a magnet approaches)
- 4 small magnets
- Magnetic lock (solenoid)
- MOSFET transistor (IRF540N) or relay to drive the magnetic lock - Arduino output cannot provide enough current directly
- No resistors needed
Fireplace
The item must have a magnet and be placed in a specific way. For the sound and LED strip:
Components needed:
- Croduino
- 1 reed or hall effect sensor
- 1 magnet
- MOSFET or relay + magnetic lock
- Buzzer (5V) for sound (8-bit sound)
- Smart RGB LED strip (WS2812, 30 LED/m, 5V, IP20) - you can control individual LED colors without additional transistors
Weirwood Tree
This is mechanically challenging. You can use reed switches or hall effect sensors, or try a light sensor to detect the difference between full darkness (eyes in place) and some light (eyes missing). Another option is RFID - more expensive but precise. Tags can be embedded in the eyes.
For the mouth: use a classic MOSFET or relay with magnetic lock.
Dragon Hearth
A vibration sensor could detect movement, but may trigger from table movement. An accelerometer (MPU-6050, 3-axis gyroscope/accelerometer) is better - it can distinguish between table movement and direct pinching near the sensor. You could also try a pressure sensor to detect squeezing directly in the hearth.
General
For cables connecting modules, check the experimental cables section. For soldering, you’ll need breadboards. Phone USB chargers can work as 5V power supplies.
I can help locate magnetic locks and reed switches locally if needed. I’ll draw schematics once you place your order.
Customer:
What is the activation range of a hall sensor? I need to know because the positions are 5x5 cm - do pieces need to be placed exactly or can they be anywhere within that 5x5 cm area?
Also, the chess table will be made from plywood, almost 2 cm thick. Is that too much for a magnet to activate a hall sensor through it?
Same questions apply to reed sensors.
Which would you recommend for best accuracy - hall or reed?
For the dragon hearth puzzle, I’m now thinking of using a pressure sensor instead. I’m concerned the vibration sensor might trigger if someone moves the table, whereas a pressure sensor could be placed directly inside the hearth.
Soldered Support:
The activation range is hard to determine precisely because it depends on the strength of the magnetic field (measured in Gauss). Your best approach is to test with the actual sensor and magnet you plan to use.
With a sufficiently large magnet, 2 cm of plywood should not be a problem.
Hall effect sensors work on a digital principle rather than mechanical, so I recommend hall sensors for better accuracy. But testing with your specific components is essential.
For the dragon hearth, how would you connect a pressure sensor? Place it inside and measure changes? If you use the BMP180 pressure sensor, an accelerometer would be better - the MPU-6050 can distinguish between table movement and direct pinching near the sensor location. This is more reliable than a vibration sensor alone.