Bistable Flip-Flop

The circuit of Fig. 17.3 should be constructed. It is bistable, because it is stable for long times in either state, with the bulb off or on. It can be set by touching the positive probe to one of the terminals (really just clip leads) and reset to 

With the bulb or another small resistor, the left-hand transistor will preferentially be turned on, when the battery is first attached. This type is called a JK type. (The reasons for choosing the letters J and K are obscure.) 

Battery, nine volts Clip leads, 14 inch, one set. 

Lamp bulb, tungsten, 12 volt dc, green or blue 272-337A Transistor, NPN (two) 276-1617 or 276-2041 

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Tests also show that the circuit of Fig. 6 can be operated as a bistable flip-flop. That is, pulsing an inductance switch shifts most of the current to the opposite branch, and the current thus shifted, remains there. This can be explained only if the flux associated with the small remaining current is trapped in the inductance switch hole. Analysis shows that each time the current is flipped, a smaller amount is shifted, until finally no shift is obtained, and the current is split evenly between the two branches. The entire process can be repeated by interrupting the loop current, pulsing both inductance switch controls, and then applying loop current again. 

In order to get this circuit to start, the UIC statement must be included in the. TRAN simulation. Flip-flops inside the model need the UIC directive in order to initialize properly. The SPICE engine has a difficult time determining the steady-state operating point of bistable circuit like the flip-flop without the UIC. Also, the ABSTOL OPTIONS parameter for current absolute current error tolerance has been changed from lp to 1/x to aid convergence. 

The basic device for counting and storage operations is the flip-flop or bistable multivibrator. The flip-flop, in its many forms, can be constructed from individual gates, but it is usually purchased as a single unit in integrated-circuit form. 

The flip-flop memory utilizes the bistable mechanism capable of trapping and release of individual bubbles. The device holds a single bubble indefinitely until it is toggled by another bubble arriving at the inlet, dislodging the... 

Electronic devices (a) Multivibrator (flip-flop) (b) Bistable operation of a laser coupled to an external resonator... 

In electro-kinetic phenomena, bistability was studied by several groups in a system of following type [35-38] the system was as follows. The plots of / (current) versus A were found to be typical N-shaped curves (Fig. 8.6). These N-shaped curves have been referred to as flip-flop type. 

A similar type of curve is obtained when A4> is varied and current is recorded. The current increases with the transmembrane potential. On attaining a certain value, it suddenly decreases (discontinuously) and then again increases linearly with slope much smaller than that found in the initial state. An N-shaped current-voltage curve is obtained which is called the flip-flop type. It is obvious that in the region of bistability, there are two values of A4> corresponding to a particular value of I. 

Biopolar junction transistors are often used as switches and logic devices. Figure 22.5 is an example of a bistable or flip-flop circuit. When voltage is applied, either Ti or T2 will conduct slightly more than the other. If Ti is conducting, the base or T2 is driven to groimd. 

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