Contact bouncing

The need to protect a rotating machine from switching surges, contact bouncing and surge transferences 17/576... 

Electromechanical analog switches exhibit some very desirable characteristics. They have essentially zero resistance when the contacts are closed and infinite resistance when they are open. They can handle a range of many orders of magnitude of voltage and current of either polarity. They also have, as might be expected, some undesirable characteristics. First, the contacts bounce whenever they are opened or closed. This can result in noise that must be filtered out. Mercury-wetted contacts can lessen bounce noise, but do not eliminate it. Second, electromechanical switches are rather slow in switching the faster ones take 1 msec or so to open or close. 

Another circuit that is often used to remove contact bounce noise is the Schmitt trigger, which is shown in Fig. 21.3. This has nicely adjustable hysteresis, without requiring two kinds of transistors. (Note that electronics designers often refer to transistors as Ql, Q2, etc.) Initially, Q2 is on and Q1 is off When Ql is turned on by raising the pot setting (simulating an incoming... 

Contacts fully made and under spring pressure (before bouncing back)... 

Trip Flares were constructed like an antipersonnel mine of the "Bouncing Betty" type, the fragmentation projectile being replaced by a flare which was projected upwards when anyone came in contact with the device. These flares were intended to give warning of the presence of enemy in their vicinity. The following may be cited as examples ... 

The attractive force between the spray droplets and the leaf surface has a given value per unit area of leaf. When the contact angle of the drop and the leaf surface is sufficiently small—i.e., when the interfacial area is sufficiently large—the force tending to cause the droplet to bounce off the leaf is matched by or equal to the attractive forces, and hence the droplet adheres to the leaf surface. 

Fig. 2. The ball actually gets warmer on bouncing. The critical time is the time the ball remains in contact with floor this defines the equivalent frequency.

We observed die wetting, splashing, and bouncing bdiavior of the dn lets coming into contact with the hot metal plate by a high-speed camera. We could thus observe the behavior of the emulsions when coming into contact with the hot metal surface. This helps to explain the product efficiency differences observed. 

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