IC 74121 PDF

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All this allows to create very simple frequency meter circuit with several frequency ranges:.

The pulse width produced by the monostable multivibrator depends on the values of capacitors C 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. 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. The load Capacitance CL is 50pF, including scope probe, wiring, and any stray capacitance.

Frequency meter with 74121 monostable multivibrator

Instead ofthe SN or DM can be used. Note the uses a 4k internal resistor, while the uses a 20k resistor.

There are two different methods of connecting Rx and Cx. You’ll need a source of stable frequency reference signal that can produces a set of frequencies Kc, 1 kHz, 10 kHz and kHz. The Figure 1 shows the circuit diagram of the frequency meter, the circuit based on the digital IC C5 and trimming potentiometers R The device can measure sinusoidal wave and square wave input signals.


How to Read Logic Truth Tables: The pulse frequency depends on the input frequency. The first chart works for either the 74L or 74L; however, the second chart only applies to the 74L All this allows to create very simple frequency meter circuit with several frequency ranges: The two graphs below show the resultant pulse width for different values of resistors and capacitors.

The Diodes used in the circuit are 1N or equivalent. While the shown below provides a retriggerable Monostable Multivibrator function with clear. This device uses the ammeter with full-scale deflection of 0. The pulse voltage is proportional to the input frequency, through the diode VD5 this voltage charges the capacitor C1. Do the same operation for all ranges. The ammeter PA1 indicates the voltage across the capacitor C1.

By the way, the ammeter PA1 can be replaced with a digital multimeter. 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.

Electronic Engineering Dictionary

Reference oscillator circuit diagram. 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. VD4 protects the integrated circuit from overloading. Adjust the trimming potentiometer R3 7421 move the needle of ammeter PA1 to the maximum value on the scale. The shown above provides a single Monostable Multivibrator function.


Frequency meter with monostable multivibrator

Also refer to Transistor Multivibrator Circuits. Digital integrated circuits can be used in the design of an analogue frequency meter with a frequency range to several MHz.

How to calibrate this frequency meter? The number of frequency ranges can be increased by using a uc switch SA1 with more than four positions, and by adding some additional RC components.

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. 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. To use the internal timing resistor connect Rint to Vcc.

A Monostable Multivibrator is also called a One Shot. 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.