A very simple trap. A watch and battery are located in the head light, set to explode at a fixed time.
The electrical current is sent along the wire to the detonator inside the vertical bar. The detonator fires, setting off the charge. Another method is to have the wire connected to the dynamo which rests against the front tyre. When to cyclist rides off, sufficient electrical current generated works the same as a battery.
A hollow section of bamboo is tied to a block of wood, which in turn is secured to a ledge or tree at chest height. An arrow is inserted into the bamboo section. The end of the arrow is secured to the release device and is fired by a rubber band attached to a trip wire.
Bamboo whips are constructed of a length of green bamboo with spikes attached to one end. The bamboo pole is bent and secured in an arched position by a catch device triggered by a trip wire stretched across the track. When released, the bamboo pole whips back into the straight position impaling the person triggering the trap.
During the wet season, the VC would use the inundated paddy fields to lay punji spikes. Moving across these paddy fields in extended formation, one was well aware that the next step could find your foot impaled on one of these things.
The Venus Fly Trap consists of a rectangular frame work with overlapping barbs emplaced in a pit, on trails or in a rice paddy. This one is made from a metal container which is sunk into the ground until the top is flush and then is covered with grass or leaf camouflage. The barbs inflict injury especially when the victim attempts to withdraw his leg out of the trap.
These were very dangerous to search because of the infinite variety of traps that could be used. Anything that could be lifted, slid, moved, opened had to be treated as suspicious.
A frequent Viet Cong Trap used in known Viet Cong camps was to place a rubber band around and over the striker lever of a hand grenade, remove the pin and hide it in the thatched roof. After searching the huts and to deny the VC of reinhabiting them, they would be torched. The rubber band would melt releasing the striker lever and detonating the grenade.