Picture of Stop Time with an LED Stroboscope!
A stroboscope is a tool which uses a bright flashing light to allow a user to view objects which are rapidly moving in a periodic manner. When the frequency of the flashing light is matched to the speed of the object, the object can appear to be stationary.

Stroboscopes are commonly used to examine moving machinery in an industrial setting. The stroboscope allows the equipment to be inspected or monitored while it is operating.

If the strobe frequency is high enough, the observer won’t perceive the flashing of the light, similar to how one does not notice the fact that a movie projection actually consists of individual frames.

This article details construction of a control circuit that can drive an array of LEDs for use as a stroboscope. The LED array can be made by straightforward modification of inexpensive LED flashlights, or a custom array can be built.

One note of caution.  Some people who have epilepsy are susceptible to seizures caused by rapidly flashing lights.  Do not use the device shown here, or any commercial strobe light around anyone who is known to have such a susceptibility!

Here is a YouTube video demonstration of just a few ways that this stroboscope unit can be used to view moving objects.

kayv1 year ago

i am a new person and i want stroboscope , in the diagram above shown is very typical may you please mail me the component list with name and specifications and may you please elaborate the circuit diagram so that i can make this project and how we can do the programing of the micro processor .

kayv1 year ago

i am a new person and i want stroboscope , in the diagram above shown is very typical may you please mail me the component list with name and specifications and may you please elaborate the circuit diagram so that i can make this project and how we can do the programing of the micro processor .

ecgrishma1 year ago

Instead of pic any other IC can be used??

Like say, 555 or mic3201 etc.

I have a flashlight that does this, It's really fun to walk around in the dark with it
ajoyraman2 years ago
Thank You for a fine illustration of the Strobe Concept.

Thanks also to all those who have made such excellent comments.

This project is a essential item to have around.
Great ible! I like PICs.

I did something similar about 5-6 years ago. I started with a prototype using a 556 dual timer to check the concept and then built a final version using a PIC driving an LCD display and a single 5W LED.

I built my strobe for a microscope illuminator so that I could observe the motion of the cilia of microorganisms. I controlled the flash period using a rotary encoder and it was settable between 1/5 sec and 1/256 sec in one continuous range which would display on the LCD. The flash duration was settable from about 5 to 250 uS. I drove 15A current spikes through the LED (5W LEDs can handle it as long as you keep the duty cycle low).

It was really surprising what could be seen using the strobe. Cilia that normally move too fast to be seen became clear as day and one could see patterns in their motion like the wave-like pattern you can see in centipede's legs when they are moving fast. Really amazing when you consider that a single-celled organism has no nervous system to coordinate the motion.
LargeMouthBass (author)  Mark Rehorst3 years ago
I would never have thought about using the stobe for viewing anything microscopic. Cool application!
I really like that you used assembly language. Too many people go immediately to higher level languages that obfuscate the CPU functions and prevent real learning about uCs. Writing assembly code for a project like this will really improve understanding of the technology.

Have you looked at using rotary encoders instead of a pot with an analog input? It is so much easier to use an encoder - a simple lookup table is all that is needed to determine rotation direction and counter increment/decrement. It's lightning fast and It will greatly simplify your code. Most rotary encoders, even the cheap ones (see here: http://search.digikey.com/us/en/cat/sensors-transducers/encoders/1966131?k=rotary%20encoder), will work more reliably and last longer than a pot.

This page has a great explanation of how to read an encoder in assembly language: http://mcmanis.com/chuck/robotics/projects/lab-x3/quadratrak.html
LargeMouthBass (author)  Mark Rehorst3 years ago
Yeah, I prefer assembly for PICs. It's all I know frankly, and it suits me fine for smaller microcontroller projects. I kind of like knowing what the processor is doing in microscopic detail.

I do see the benefits of an encoder, and I have some sitting around that I've intended to use on projects but just haven't ever gotten around to it. I may do a second version of this project that uses an encoder instead.

I would also have liked to add an LCD for frequency and on time readout like you have, but I built this stobe project using a custom general purpose PCB that was only laid out for an 8 pin PIC processor.
I built my controller using a PIC-MT-USB (http://www.olimex.com/dev/pic-mt-usb.html) made by Olimex with a PIC18F874 . I selected it for the number of IO pins available and the LCD display. I never used the USB port.

All I added was a 15V 5A power supply, a 5V regulator to power the board from the 15V supply, power FET switch to switch current pulses into the LED, and the encoder. The 5A supply charged a capacitor that rapidly discharged through the LED to get 15A pulses.

One nice thing about encoders is there is no mechanical stop- you can just keep spinning and spinning the thing eliminating the need for range switching. You can make the increment/decrement function speed-sensitive so that you get fine control for slow rotation and quick jumps for fast rotation.
X-mind3 years ago
This is the ultimate DIY slow-motion capture equipment :)
jabbawokie3 years ago
Nice iv been wanting to make 1 of these for ages but alot of the circuit diagrams i could find wer rather complex i dont know why i never thought about using a microcontroller!! good stuff mate :)
There are other 556 versions that blink so rapidly that it is hard to see.
Eurober3 years ago

A well-done project. For people that do not want to use a microprocessor-based solution, the 555 timer could be implemented to perform the main function. In spite of the lower accuracy (could be improved by careful calibration) the circuit would be simpler and easy to put together.