schematic knowledge

Showing posts with label frequency. Show all posts

Friday, April 12, 2013

Mains Frequency Monitor

Here is a simple frequency counter designed to monitor the 240VAC primarys provide. It as a frequency range of 0-999Hz, so it may be used with 400Hz equipment. Standard TTL/CMOS common sense is employed for the counters and display drivers, whereas an ELM446 (IC1) generates accurate 1Hz pulses for gating. This instrument make the most ofs a 3.579545MHz crystal for its timebase, as usually found in TV and video circuits and even on previous PC motherboards.

Circuit diagram:
$\"mains-frequency-monitor-circuit$

Mains Frequency Monitor Circuit Diagram

Saturday, April 6, 2013

Frequency to Voltage 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 frequency-to-voltage conversion process.

Frequency to Voltage Converter

Feature-owned single-chip LM2917 Frequency to Voltage Converter

Reference to ground directly with variable reluctance
Op Amp / Comparator with transistor output
50 mA maximum output currents for application directly to the load
Frequency doubling untul low ripel
Buid in zener
Linear output ± 0.3%

Application single chip LM2917 Frequency to Voltage Converter

Frequency to Voltage Converter
Rotation speed sensor applications
Speedometer
Tachometer
Cruise Control
Cluth Control

And other application associated with the measurement of rotation speed or frequency measurements.

Thursday, March 28, 2013

Frequency Doubler

If you are working at frequencies of the order of 850MHz to 4GHz and ﬁnd that a frequency multiplier is required, the HMC 187, HMC 188 and HMC 189 (see table) frequency doubler may be just the solution you are looking for. The isolation performance of these devices ensures that the input frequency (fin) and its harmonics 3fin and 4fin are attenuated by 35dB relative to the wanted output frequency 2fin. This excellent isolation specification reduces the need for additional output filtering and is also an advantage where several doublers are connected in series to produce four or eight times the input frequency.

Frequency Doubler Circuit Diagram

The tiny outline of the HMC18x- series device occupies a board area of 3mm by 4.8mm and measures just 1.07 mm high. Internally the device contains balanced to unbalanced transformers (baluns) to match the doubler circuit with the output and input. The doubler circuit itself is passive and comprises a full wave Schottky diode bridge rectifier. The monolithic baluns which are integrated on-chip give the device a relatively high low-frequency roll-off at 850MHz.

Table of Frequency Doubler Circuit Diagram

Lower frequencies can also be multiplied but the conversion loss factor (given as typically 15 dB) will increase. The input and output are matched for 50 Ohm operation and the input signal level should be of the order of +15dBm which will give a output level of approximately 0dBm. The main characteristics of the three versions of this device are summarized in the table above.

Monday, March 25, 2013

Remote Control Circuit Through Radio Frequency Without Microcontroller

Description

This is a simple type remote control by using RF communication without microcontroller. In this project a remote has been designed for various home appliances like television, fan, lights, etc. It gives lot of comfort to the user since we can operate it by staying at one place. We can control any of the appliances by using this remote within the range of 400 foots. In this project consist of two sections, transmitter (remote) and receiver section. Whenever we are pressing any key in the remote it generates the corresponding RF signals, and these signals are received by the receiver unit. ASK transmitter and receiver is used as transmitter and receiver. HT12E, HT12D encoders and decoders are used in this electronic circuit. The block digram of the whole circuit is given below.

Appliance Control Block Diagram

Remote Section

In remote section consist of an encoder (HT 12E) and a ASK transmitter. The encoder generates 8 bit address and 4bit data. We can set the address by using the DIP switch connected in A0 to A7 (pin 1 to 8 ) encoder. If we set an address in the remote section, the same address will be required in the receiver section. So always set same address in transmitter and receiver. Whenever we press any key in the remote the encoder generates corresponding 4bit data and send this data with 8bit address by using ASK transmitter. The transmitting frequency is 433MHz. The transmitter output is up to 8mW at 433.92MHz with a range of approximately 400 foot (open area) outdoors. Indoors, the range is approximately 200 foot.

Remote or Transmitter Circuit

Receiver Section

At the receiver section ASK receiver is present. The receiver also operates at 433.92MHz, and has a sensitivity of 3uV. The ASK receiver operates from 4.5 to 5.5 volts-DC, and has both linear and digital outputs. It receives the datas from the transmitter. Then the decoder (HT 12D) decodes the date and it will enable the corresponding output pin (pin 10,11,12,13). Each output pins are connected to separate flip flops. The output of encoder will change the state of the flip flop. So its output goes to set (high) from reset (low) state. This change makes a high signal in the output of the flip flop. This output signal is not capable to drive a relay directly. So we are using current driver, SL100 transistor act as the current driver. The appliance is connected to 230V AC through the relay and the appliance will start. The relay will be re-energized when the same switch is pressed in the remote. This is because we are pressing the same switch in the remote control. The output of the decoder again goes to high so this signal will again change the state of the flip flop. So, the relay gets re-energized and the appliance goes to OFF state.

Remote Control Receiver Circuit

Components Used


IC	HT 12D	1
	CD 4017	4
	LM 7805	2
TRANSISTOR	BC 558	4
	SL 100	4
RESISTOR	180 K	4
	1 K	4
	560 E	4
	39K	1
	1M	1
CAPACITOR	100nF	4
	100MFD/16V	4
LED	RED	4
DIP SWITCH		2
PUSH TO ON SWITCH		4
ASK TRANSMITER	433MHZ	1
ASK RECEIVER	433MHZ	1