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A retriggerable monostable multivibrator and a D flip-flop can form a simple, yet reliable frequency comparator that compares an input frequency with a predetermined reference. To determine whether an input frequency (f) falls between two known frequencies, f1 and f2, two one-shot/flip-flip combinations are used, as shown. Here both the one-shot and the flip-flop ICs are wired for positive-edge triggering. Each input pulse causes the monostable output to go high for the period of its preset timing interval. The flip-flop is triggered simultaneously, but its output is determined by the state of its D input at the time of trigger threshold. If the period of the input frequency is shorter than the preset timing of the monostable, a constant high level will be present at the D input, forcing the flip-flop’s Q output to remain high. If the input frequency period becomes greater than that of the monostable, the flip-flop’s Q output will go low. VR1, VR2, and C1, C2 determine the value of...

Super heterodyne receivers have been mass-produced since around 1924, but for reasons of cost did not become successful until the 1930s. Before the second world war other, simpler receiver technologies such as the TRF receiver and the regenerative receiver were still widespread.   Circuit diagram :   Tuned Radio Frequency (TRF) Receiver Circuit Diagram   The circuit described here is based on the old technology, but brought up-to-date a The most important part of the circuit is the input stage, where positive feedback is used to achieve good sensitivity and selectivity. The first stage is adjusted so that it is not quite at the point of oscillation. This increases the gain and the selectivity, giving a narrow bandwidth. To achieve this, the potentiometer connected to the drain of the FET must be adjusted very carefully: optimal performance of the receiver depends on its setting. In ideal conditions several strong stations should be obtainable during the day using a 50 cm antenn...

This is a Line Frequency Square Wave Generator Circuit Project. A square wave is a non-sinusoidal periodic waveform (which can be represented as an infinite summation of sinusoidal waves), in which the amplitude alternates at a steady frequency between fixed minimum and maximum values, with the same duration at minimum and maximum.   Line Frequency Square Wave Generator Circuit The transition between minimum to maximum is instantaneous for an ideal square wave; this is not realisable in physical systems. Line Frequency Square Wave Generator Circuit Project with only three components and a buffer, a line frequency square wave having a 1:1 duty cycle may be derived from the power supply.  During the alternate half-cycle, however, A is effectively clamped to - 0.7 V by Dl in the bridge which offsets the forward voltage across D2 giving an input to IC1 of approximately 0 V. When A rises above + 5 V, D2 is reverse biased and remains at +5 V. Rl is needed to load the transfor...

Circuit Diagram Description The circuit was designed to create a low cost frequency meter that will cover the range of 1 Hz to 1 MHz with a digital indication using three 7-segment displays. Terminology 7805 – a 3-terminal 1A positive voltage regulator with output transistor safe area compensation, internal short circuit current limiter, output voltage of 5V, 12V, and 15V, internal thermal overload protection, no external components, and current output in excess of 0.5A 4026 – a decade counter where the count advances as the clock input becomes high and has a maximum current of about 1 mA with a 4.5 V supply and 4 mA with a 9 V supply, which can light the appropriate segments of a common cathode 7-segment display 4583 – a 4-bit single-chip microcomputer designed with CMOS technology using a simple, high-speed instruction set, equipped with four 8-bit timers, a 10-bit A/D converter, interrupts, oscillation circuit switch function, and used in application with remote control transmitt...

Changing the voltage to frequency scale in the design of an electronic device is sometimes necessary. The series of articles voltage to frequency converter with the XR 4151 is one answer. Voltage to Frequency converter circuit with the XR 4151 is the idea of time in college, when there are projects to create a tool to hatch chicken eggs. It will be my neighbor also write articles incubators chicken egg-based microcontroller AT89C2051. Maybe there are friends who still remember to this project. Back to the topic of voltage to frequency converter circuit with the XR 4151. IC XR 4151 is a major component of voltage to frequency converter (Voltage to Frequency Converter). From voltage to frequency converter circuit with XR 4151 on the input signal circuit is a DC voltage level. IC XR4151 on voltage to frequency converter circuit serves to convert the voltage level coming into form in the development of the frequency change, where the output frequency range of voltage to frequency converter...

Overview of IC LM2917 as Frequency to Voltage Converter IC LM2917 IC chip is designed specifically as a Frequency to Voltage Converter or Frequency to Voltage converter. In its use to applications Frequency to Voltage Converter IC LM2917 requires few external components. There are several examples of applications of Frequency to Voltage Converter IC LM2917 is supplied in the LM2917 IC datahseet. In this article series Frequency to Voltage Converter IC also taken from the LM2917 datasheet. The advantages of single chip LM2917 Frequency to Voltage Converter is able to provide instantaneous volt output o at time of frequency change 0 Hz. Very easy to apply in measuring the output frequency with the formulation of single-chip Frequency to Voltage Converter VOUT = FIN x VCC x R1 x C1. Then the single-chip LM2917 Frequency to Voltage Converter This configuration requires only the RC only in frequncy doublings. And has an internal zener regulator to aimlessly accuracy and stability in frequen...

How to Make a Frequency Generator . On cloud busters Fredbuster created a wonder tutorial for getting started and building your own Zapper. Fredbusters Tutorial in PDF-Based off his design here is how I made my frequency generator. Frequency Generator Circuit Diagram Parts Needed 1 Project box with PC board included, 1 Compositor 1 micro farad, C2, I like the un-polarized because it allows you not to worry about positive an negative sides. If you do get one with a longer leg that's the positive, see schematic for proper placement. 1 Compositor .01 micro farad, C1 1 LED 1-3 volt, small red ones. Remember the longer leg is the positive, connect properly, 1 Resistor 3.3k ohm, R1, It will say it on the upper part figuring out the colors is a pain. See photo below for product ID. 1 Resistor 3.9k ohm R4 1 Resistor 4.7k ohm R5 1 Resistor 1k ohm R3 for creating a body zapper with pennies, 1 resistor for R2 see Fredbuster's PDF file for specific resistor for frequency. I use variabl...

AUDIO FREQUENCY LIGHT MODULATOR ELECTRONIC DIAGRAM Light has function to replace cable from audio source to speaker. Transformer X2 is utilized to lock the audio signal. VR1 works as the amplitudo modulator from the T1 signal output. Parts list :     Resistor R1:  47k ohm     Resistor R2 : 22k ohm     Resistor R3 : 220 ohm     Diode D1-D7 : 1N4001     VR1 : 1k ohm     Polar capacitor C1 : 470 uF/25V     Polar capacitor C2 : 1 uF     Capacitor C3 : 0.1 uF     Transistor T1-T2 : BC148     Transformer X1 : 220 V AC/0-12V AC     X2 : AF output     Transistor SCR1-SCR2 : BA654

Description This frequency doubler uses one CMOS quad, two input NAND gate package type 4011. The frequency doubler proper consists of an inverter IC1B, two differentiating networks R1/C1, R2/C2 and NAND gate IC1A, IC1C and IC1D function as input and output buffers. In Fig.2 exist the pulses in different points of circuit. Circuit diagrams Source  http://users.otenet.gr/~athsam/frequency_doubler_with_4011.htm

Transformer – Coupled Amplifier The main drawback of RC coupled amplifier is low voltage and power gains and poor impedance matching. This is because of the decrease in effective load R AC of each stage. If the effective load resistance of each stage could be increased, the voltage and power gain could be increased. This van be achieved by transformer coupling. Transformer coupling is generally employed when the load is small. It is mostly used for power amplification. Transformer Coupled Amplifier  The above fig shows the two stage transformer coupled amplifier in this circuit the primary of transformer is placed instead of R C . The secondary of transformer replaces a wire between the voltage divider network and base of second stage. The resistors R 1 , R 2 , and R E forms the voltage divider bias and stabilization resistors. The capacitor C E bypass the resistor R E . Operation: The input signal is applied to the base of the first transistor through the capacitor. The amplifie...