Monday, March 13, 2023

Twitch-n-Howl board v2.2 — prop controller with sensor triggered and random activation of light, movement, and sound

It’s alive…

Movement is great. So are lights. But sometimes things are a bit too quiet and predictable.

Open source design. Open source code. Fully end-user modifiable. Footprint smaller than a playing card.

About a year ago I started working on a prop controller for my Halloween display. I wanted something that would deliver bursts of movement and synchronized audio. It needed to be trigger-able by a sensor, but also have some “background level” of activity that was unpredictable and added to the ambiance of the haunt. It’s taken some time, but I finally have something that’s ready to share with the haunt community. 

The Twitch-n-Howl board is a single sensor, single event (12v output plus sound) trigger board. In the untriggered state, events are randomly triggered at a modifiable low background rate. When triggered, the controller switches to an ON-state giving more frequent events. 

Sounds Great! How do I get one?

Check out the Jekyll-Labs Store and send me a message though the Contact Me box. If you’d like to learn more, keep scrolling down.


A variety of sensors and buttons can be used to trigger the Twitch-n-Howl board. I’ve tested it with buttons, PIR sensors, and capacitive touch sensors. It is set to respond to a “HIGH” state, so anything that connects the +5V line to the sensor line will trigger it just fine.

Random Background Rate

The (pseudo)random background event rate for the Twitch-n-Howl board is based on a Poisson process. If you’re interested in traveling down that particular rabbit hole, click here to read my blog post on the topic. Otherwise, it’s sufficient to know that this results in a background frequency of events that feels less predictable. Events occur both earlier and later than your brain expects. 


The 12v output can be used to run a multitude of props. I've set it up with flashes of light (for a cannon or for a jump scare) and a variety of motors (from 12v wiper motors to 3v small DC motors). If the prop has a button activation (for a try me sensor or a fog machine trigger) a Bosch automotive relay works perfectly. It's also easy to control AC (fans and lights) with a solid state relay. The duration of the output is controlled by the duration potentiometer dial. 


Sound effects are supplied by the JQ-8900 16P daughter board. This board has a USB port and when connected by a cable is recognized by most PCs as a USB thumb drive. It is a simple matter to rename your files as 0001.MP3, 0002.MP3… and then drag and drop them to the JQ-8900. When an event occurs (triggered or background), the board will randomly play one of the MP3 files. Audio is available as line level output or 3 watt amplified output which can run a medium sized speaker. 

Open Source

Jekyll-Labs builds products for makers. We want you to take what we’ve created and push it further. All of our designs are open source schematics and open source code. The Twitch-n-Howl board is fully end user modifiable. It uses the same chip as the Arduino Uno and new source code can be written and uploaded using the Arduino IDE. Make the Twitch-n-Howl board what -you- want it to be.


The Twitch-n-Howl board has a footprint approximately the size of a standard playing card. As such it will fit in a wide variety of different enclosures. The PCB was initially designed to fit in the Z&X G713 waterproof electrical box. It is a sturdy box with a nice silicone gasket. Jekyll-Labs does not recommend trying to set it on fire or leaving it underwater without additional sealing (as the manufacturer suggests), but for standard weatherproofing, it seems great. You can purchase the enclosure separately from amazon, but if you it from Jekyll-Labs, the case will also protect the device during shipping.

Links to Sample Projects (coming soon)

Additional Pictures

No comments:

Post a Comment