This can crusher display crushes cans in milliseconds using a very high current pulse.
“Continue reading” for more details and photos.
It is an upgraded version of Can crusher 3 that I built up for the Physics Department at the Uni of Western Australia. The previous defibrillator capacitors did not last long and I have now installed a “proper” pulse rated Maxwell capacitor rated at 131 uF, 8 kV, 100 kA, 80% reversal which stores 4 kJ. Typically it will only be used to 2 kJ so even though it is second hand with unknown history, it will hopefully not be particularly stressed and have a reasonable lifespan. Physically it bolts nicely on the bottom of the microwave shell and I can still keep the wiring path fairly short. In view of the 70 kg weight, I have built the can crusher onto a furniture removal trolley. Simpler and cheaper than anything I else I could come up with.
The can is positioned to be ejected with the base of the can halfway into the coil. For normal can crushing the block is removed and the can inserted fully.
Current can be measured on the ground return wire using a Rogowski coil. It also shows the heavier coil that is not as efficient as the wire core is not as close to the can surface. The CRO has a 10 kA/div scale vertically and 20 us/div horizontally with a 6 kV shot (= 2.1 kJ). The peak current in the 3 turn coil is 40 kA which corresponds to a current within the can of about 80 kA. Resonant frequency is 13 kHz with the large cap and longer wiring.
The right photo shows the capacitor specifications of 131 uF, 8 kV and 0.08 uH. It is rated at 100 kA and 80 % reversal.
Performance is good with easy crushing of the can at 4 kV, 860 J or tearing it apart with 6 kV, 2000 J. By positioning the can just out of the coil, it can be propelled 15+ feet into the air. This is in effect a Thompson gun.
The left photo shows the deformed Coke can 15 feet in the air (basketball backboard is 12ft). The right photo shows the red Coke can from the first photo showing the deformity. The black Coke can has a goblet shape as it was a little too far into the coil to project properly.
Further improvements could include faster charging with switchable energies. Also I have had requests for a microwave oven like “ping” when it is cooked! I have a large LED digital display that I had hoped to adapt to a large voltmeter.
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Information Unlimited Can Crusher
Photo Date: June 25, 2006