Description and operation of a 74L and Monostable Multivibrator. The shown above provides a single Monostable Multivibrator function. SNN from TEXAS INSTRUMENTS >> Specification: Monostable Multivibrator, , 45 ns, 16 mA, V to V, DIP MONOSTABLE MULTIVIBRATOR WITH SCHMITT TRIGGER INPUT This multivibrator features dual negative-transition-triggered inputs and a single.
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– Monostable Multivibrator
The number of frequency ranges can be increased by using a rotary switch SA1 with more than four positions, and by adding some additional RC components. The pulse voltage is proportional to the input frequency, through the diode VD5 this voltage charges the capacitor C1.
Turn the rotary switch S1 of the frequency meter to the range of Hz and connect the device to the reference signal source of Hz. While the shown below provides a retriggerable Monostable Multivibrator function with clear.
The pulse frequency depends on the input frequency.
The first method for a Cx of less than pF [below] and a second connection [below that] for an external capacitor, Cx, of greater than pF. A quartz crystal oscillator circuit that can generates kHz signal with a 3-stage decade counter can be used as a reference frequency source see the Figure 2.
A Monostable Multivibrator is also called a One Shot. The ammeter PA1 indicates the voltage across the capacitor C1.
Frequency meter with 74121 monostable multivibrator
Note the uses a 4k internal resistor, while the uses a 20k resistor. This IC is the monostable multivibrator that may generate a pulse of a different width from 35 ns and wider that depends on RC components.
The two graphs below show the resultant pulse width for different values of resistors and capacitors. All this allows to create very simple frequency meter circuit with several frequency ranges: By the way, the ammeter PA1 can be replaced with a digital multimeter.
The Figure 1 shows the circuit diagram of the frequency meter, the circuit based on the digital IC C5 and trimming potentiometers R Digital integrated circuits can be used in the design of an analogue frequency meter with a frequency range to several MHz.
All this allows to create very simple frequency meter circuit with several frequency ranges:. Adjust the trimming potentiometer R3 to move the needle of ammeter PA1 to the maximum value on the scale.
Do the same operation for all ranges.
There are two different methods of connecting Rx and Cx. You’ll need a source of stable moonstable reference signal that can produces a set of frequencies Hz, 1 kHz, 10 kHz and kHz.
How to Read Logic Truth Tables: The load Capacitance CL is 50pF, including scope probe, wiring, and any stray capacitance. This device uses the ammeter with full-scale deflection of 0.
Instead ofthe SN or DM can be used. The first chart works for either the 74L or 74L; however, the second chart only applies to the 74L How to calibrate this frequency meter? The circuit could be used for any TTL family, such as LS, or H, but the load capacitor might need to be changed to reflect that.
To use the internal timing resistor connect Rint to Vcc. The Diodes used in the circuit are 1N or equivalent. The shown above provides a single Monostable Multivibrator function.
Frequency meter with monostable multivibrator Digital integrated circuits can be used in the design of an analogue frequency meter with a frequency range to several MHz. VD4 protects the integrated circuit from overloading.
The pin out diagram works any any style 74xx or 74xx DIP chip, but the timing graphs are only valid for the TTL families indicated.
or Timer as a One-Shot
Reference oscillator circuit diagram. The pulse width produced by the monostable multivibrator depends on the values of capacitors C The device can measure sinusoidal wave and square wave input signals. Also refer to Transistor Multivibrator Circuits.