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Escape Room Stroboscope Prop

Noah Dalton

Apr 26, 2017
Apr 26, 2017
I built a prop for our escape room that involves making a hand crank LED spotlight into a stroboscope so you can freeze a rotating disc on a motor.

There were so many other elements to designing this that I completely forgot about making sure the duty cycle was low enough to actually freeze the image. For whatever reason, I was thinking matching the frequency was good enough. I didn't consider that the strobe actually had to have such a low duty cycle to be effective. My current duty cycle is about 20% and obviously that is way too high to actually get a stable image. The strobe has to run between 0-100 Hz by a user controlled puzzle.

I checked with a function generator and I need to get the duty cycle from 20% down to around 1% to freeze the image. So... the core requirement is to essentially take a 5V pulse train and reduce the duty cycle from 20% down to 1% while maintaining a 0-100 Hz frequency. I haven't been able to come up with any easy way to do this given the wide range of frequencies I need available. Other requirements in order of priority are as follows. Some other minor details you may need to know...

1. The pulse train output is generator by a Red Lion device model VFC10000 that takes a 0-10V input and outputs 5V pulse train based on the analog input. This goes through a solid state relay to drive the LED's which run at 24V.

2. The puzzle for this requires that the light still be usable when the strobe is at 0 Hz. ie, when the input to the Red Lion device is at 0V, the strobe should function as a normal light that can be turned on and off with the hand crank generator. This all currently works, but any changes to the circuit should still allow for this. I don't care if the circuit change is in the higher voltage section after the relay or the lower voltage section before the relay so long as it works.

3. Amazingly, the LED's are still producing enough light at a 1% duty cycle to be visible especially as the room they are used in is already dark. That being said, if there is a way to overdrive them slightly in the same circuit to account for the lower light output due to the small duty cycle, that would be good.

4. Lastly, as you may have noticed, I am trying to stick to off the shelf components that are easily integrated onto a DIN rail or very industrial in nature. Given that this is in an escape room and is abused, these components typically hold up better. I realize at this point, I may very well have to compromise since I screwed up my design here, but if whatever board or IC I use can be easily integrated into a terminal block or a DIN rail mount, that would be good.


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