Build Your Own Popcorn Strobe

Flashing Circuit Strobe Light

Skill Level: Beginner
Assembly Time: 1 Hour
Designer: Joe Klemencic aka "Trowelfaz"

Popcorn Strobe The Popcorn Strobe produces a flashing circuit similar to a strobe light. It is intended to fit inside of a plastic dome that you get from gumball machines.

In order to control the rate of flash simply adjust the potentiometer. This is a great small circuit demonstrating 555 Monostable circuit operation, perfect for creating special effects.

Build Your Own Popcorn Strobe

Required Tools and Components:

555 Timer
100K Trimmer Potentiometer
10K Ohm 1/4W Resistor
4.7K Ohm 1/8 Watt Resistor
10µF Radial Capacitor
5MM White LED
Printed Circuit Board
Soldering iron and solder
12V power source
Vending machine capsule (optional)
Hook-up wire

Step-by-Step Instructions

Step 1 – Install the LEDs

Solder on the 4 white LEDs to positions L1, L2, L3 and L4. Make sure to take note of the orientation, for the LEDs have positive and negative legs. Looking at the back of the LED, the 'straight' segment should align to the straight line on the PCB. The connections to the center of the LED should align to the angled lines on the PCB. The LED outline on the PCB has a shaved corner to assist with alignment.

Step 2 – Test the LEDs after installing

Test that the LEDs have been properly installed. Using the leads from a 9V-12V power source, insert the positive cable to the '+' hole on the PCB (do not solder it, just hold it). Next tap the negative lead to the upper leftmost LED (L1) led by the '-' symbol. All 4 of the LEDs should be illuminated.

Installing the LEDsInstalling the LEDs

Testing the LEDsTesting the LEDs

Step 3 – Soldering the 555 timer chip

Insert and solder all 8 legs of the 555 timer. Make careful note of the orientation. The notch in the chip is to be aligned with the notch in the graphic on the PCB.

Step 4 – Soldering the transistor

Insert the transistor into position, taking note of the orientation as directed on the PCB. Solder each of the 3 legs and trim to length.

Soldering the transistorSoldering the transistor

Soldering the resistorsSoldering the resistors

Step 5 – Soldering the resistors

Insert and solder the 10K and 4.7K resistors. Orientation is not important. The 10K resistor (brown. black, orange) is installed just under and left of the transistor (marked R2). The 4.7K resistor (yellow, violet, red) is installed next to the 555 timer next to pins 7 and 8 (marked R1).

Step 6 – Soldering the trim potentiometer

Add the 100K trim pot. This pot is used to control the flash rate. Insert and solder the 100K trim pot according to PCB. It will be located to the right of the 4.7K resistor.

Step 7 – Soldering the radial capacitor

Install and solder the 10µF radial capacitor as directed by the PCB. Take note the positive side of the capacitor is to be aligned with the '+' sign on the PCB just above the capacitor graphic. The negative (striped marking on the capacitor) will go towards the bottom of the PCB. After you are done soldering, trim the leads.

Soldering the Radial CapacitorSoldering the Radial Capacitor

Attach the wiresAttach the wires

Step 8 – Attach the power wires

Go ahead and fish the 12V power wires through the circle cutout from the underside of the PCB to the top of the PCB. Insert the stripped ends of the wire through the corresponding power holes ('+' for 12V positive, '-' for 12V negative/common). Then solder the wires to the underside and snip the tails.

Step 9 – Attach strobe PCB tothe base

Once completed you can now attach the built PCB to the dome lid of the vending machine capsule, or any enclosure you see fit. To accommodate the power wires drill a small hole in the back of the dome. Feed the power wires through the hole. To hold the PCB and dome lid together, you may want to tape or hot glue them together.

Step 10 – Finished project

Snap on the clear plastic dome. Hook up the wires to your 12VDC power source and enjoy your strobe action. In order to increase or decrease the flash rate turn the potentiometer.

About the Designer

Joe Klemencic is a Computer Security manager by day and a Holiday Light enthusiast by night. His year round hobby is designing, building and programming lights and circuits for his computer controlled holiday lights display. While Joe is still a novice when it comes to electronics, most of his display elements cannot be purchased in stores, so they must be fabricated by hand. Microcontrollers and electronics play a big part in bringing it all together, and offer a vast opportunity to learn many aspects about electronics while creating art for others to experience.