Electromagnetic Can Crusher

The capacitor bank stores lethal amounts of energy at voltages exceeding 3000V. ALWAYS turn off the power supply before discharging. NEVER touch the coil or internal components while the system is plugged in. Always unplug the unit after use. The bleed resistor R2 will discharge the capacitors over time, but use the shorting wand to verify complete discharge if troubleshooting is required.

Can fragments can become projectiles with sharp edges traveling at high velocity. Maintain a minimum 10-foot safety perimeter from the coil. Warn audience before discharge. Never use liquid-filled cans—the pressure can cause explosive failure. The coil's plastic wrap and fiberglass encasement provide some containment but are not foolproof.

The Ignitron switch and can crushing produce a loud metallic bang that may startle students. Warn the audience immediately before firing. The Ignitron design is specifically chosen to be quieter than spark gap switches, but the can's failure produces significant noise (80-90 dB).

ONLY use empty aluminum cans. Never attempt to crush steel cans (insufficient conductivity) or cans containing any liquid (explosion risk). Always verify power supply is OFF before discharging capacitors—this prevents simultaneous charging and discharging. Keep the apparatus unplugged when not in use to prevent accidental activation.

Any maintenance or troubleshooting must be performed with the unit unplugged and capacitors fully discharged. Use the shorting wand to verify discharge before opening any panels or touching components. Even with the bleed resistor, capacitors may retain dangerous charge.

Purpose

A high-voltage capacitor discharge through a coil induces powerful eddy currents in an aluminum can. By Lenz's law, the induced currents repel the coil's field with enough force to crush the can in under a millisecond. A dramatic demonstration of electromagnetic induction and energy conversion.

Crushing coil wrapped in fiberglass and tape atop the apparatus, surrounded by several crushed Pepsi cans showing various degrees of compression

Control panel with Varian Associates power supply, on/off buttons, indicator lights, analog voltage meter, and firing plunger visible at top

Full can crusher apparatus on rolling cart with wooden frame, clear acrylic safety panels, high-voltage warning labels, and storage bin of soda cans on top

Rear view through acrylic panel showing two large capacitors, Ignitron tube, wiring, bleed resistors, and safety labels

Figure 1: The four-turn copper crushing coil (encased in fiberglass/epoxy) with crushed aluminum cans showing different voltage settings — from a pinched waist at 3 kV to fully severed at 3.5 kV.

Figure 2: Control panel: the Varian power supply charges the capacitor bank. The analog meter monitors voltage. The wooden plunger at top fires the Ignitron switch to discharge.

Figure 3: Complete can crusher on mobile cart. Internal components (capacitor bank, Ignitron tube) are visible through clear acrylic panels. High-voltage warning labels are prominent.

Figure 4: Rear view showing the parallel capacitor bank, Ignitron tube (mercury vapor switch), bleed resistor, and protective diode. The shorting wand (wooden rod, lower left) is used for safe manual discharge.

Danger: High Voltage Hazard

Warning: Projectile Hazard

Warning: Loud Discharge Sound

Danger: Important Safety Protocol

Danger: Maintenance Warning

Purpose

Safety Warnings

Danger: High Voltage Hazard

Warning: Projectile Hazard

Warning: Loud Discharge Sound

Danger: Important Safety Protocol

Danger: Maintenance Warning

Purpose