4 Transistor 500mW FM Transmitter Circuit Diagram

4 Transistor 500mW FM Transmitter Circuit Diagram

As shown, the audio ascribe is a microphone, which uses 2 x 2N3904 as the microphone audio preamplifier. The audio/mic ascribe akin is adjustable by agency of a 5k preset / potentiometer.

The ambit uses a Colpitts oscillator for abundance generation, which is chargeless active and operates at the axiological abundance i.e. no circuitous abundance multiplication or control. The abundance affability basic of the ambit consists of 2 5pF (picoFarad) capacitors and a distinct 10uH (micro-Henry) inductor. These apparatus can be adapted if a change in abundance is appropriate - conceivably alike replaced with capricious capacitors (if youre up to the challenge).

An achievement RF amplifier takes the abundance produced by the Colpitts oscillator and amplifier to about about the 500mW (0.5 Watt) ambit - so this is the almost achievement ability of this FM transmitter. You are brash that back this transmitter operates at the axiological frequency, and because there is no achievement filter, there is acceptable to be some abundance alluvion and harmonics/spurious emissions.

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Class B audio amplifier based on TDA1553

Here is the circuit of a Class B audio amplifier based on TDA1553. TDA1553 is a monolithic audio amplifier class B, containing 2 x 22 watt amplifier in bridge configuration load attached. The amplifier operates from 12V DC and develops intentionaly for car audio applications. The IC also has a lot of good features such as short circuit protection, protection of the load dump, reverse polarity protection, speaker protection, etc.

In the circuit, C5 and C4 are decoupling capacitors C3 input, while setting the delay for speaker protection. C1 and C2 are filter capacitors of the offer.

Notes :

• Assemble the circuit on a good quality PCB.
• Use 12V DC for powering the circuit.
• The circuit can deliver 22W per channel into 4 ohm speakers.
• Fit the IC with a proper heat sink.

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Auto Sound Systems are Becoming Entertainment Systems

If youve been shopping lately for an auto sound system then I am fairly certain that youve come across several full entertainment systems among those in the running for your audio and entertainment dollars. Vehicles today offer everything from DVD players, individual speakers, headphones (also individually adjustable), and even dual players that will allow one different audio to be played in one section of the vehicle than another. In addition to all of these wonderful and nifty devices are many more devices that are meant to tempt, sway, and convince you to spend even more money on the auto sound system of your dreams. Some of these even offer MP3 players that connect directly to the audio system of your car, truck, or SUV.

The jury is still out for many people about the safety and sense of having a DVD player in your automobile. While this is the case, people will continue purchasing DVD players are part and parcel of their sound and entertainment systems and manufacturers will continue putting together attractive packages that offer these devices to consumers while offering incredible bargains on installation. I know that many feel that this is an unnecessary distraction to drivers. Im one of the rare people that feels that in a day of laptops, cell phones, talk radio, fast food, Starbucks coffee, and multitasking, a DVD in the back might be one of the best features that can be added to the car in an effort to minimize distractions coming from the direction of disgruntled passengers in the rear.

I will confess that many people wonder what this has to do with an auto sound system and I can understand that question so please bare with me. One of the features that sound system manufacturers are offering is a feature that allows individual headphones for passengers in the back along with LCD monitors that rest in the back of the head rests so that passengers in the back can both see and hear the DVDs being played without causing a distraction for the driver (either by noise or by means of flashing lights).

The truth of the matter is that having the noise from a DVD player in the back is no worse of a distraction than having disgruntled children competing for your attention from the backseat or listening to audio books as you drive along. I must admit that audio books are one of my current and readily admitted addictions. The problem with those is that on occasion some of the books simply arent meant for young ears. I try to keep my books limited to popular stories that are suitable for children whenever my children are riding along and save the sometimes steamy and often hilarious tales of Stephanie Plum for when Im riding alone. Another great reason to make sure you have an auto sound system that at the very least reads and understands MP3s.

The technology exists for this and I expect to see even more innovations technologically speaking in the way of auto sound systems and entertainment systems in the near and not so near future. We live in a world where technology is constantly evolving and we should see many new and wonderful features that will make our lives much more enjoyable for our daily commute.

Whether you are new to the technology of today, fighting it mightily, or happily embracing it-it isnt showing any signs of stopping or slowing down. This means that you will eventually have to face the fact that the old ways of buying an auto sound system will soon be obsolete. I often joke that we are rapidly becoming a society that is catching up with the "Jetsons" vision for the future. I also loudly lament my lack of a Rosie. At any rate, I am glad to see that the new technologies in auto sound systems are offering less of a one size fits all image and offering much more individual systems, even for passengers within a vehicle.

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Smart Tracker track anything from your child to shoes

The EPE Minder consists of two type- approved transmitter units and a receiver. If either transmitter becomes separated from the receiver, a buzzer in the latter part will sound.
The receiver is fitted with a switch to allow the use of only one transmitter if required.

MIND HOW YOU GO

This system was originally designed as a two-channel child alarm (to protect either a single child or two children at the same time) but many other applications spring to mind. For example, one transmitter could be placed inside a briefcase and another in a coat pocket. If the user forgot to pick up either of these items and walked away, the buzzer would sound in the receiver. The receiver must be carried on the per- son in a way that would make it practically impossible to lose it. This could be done using a belt clip, for example. Note that it will not be possible to use this system if either the transmitter or receiver were placed inside metal containers or if there were substantial metallic “screening” objects between them.

OPERATING RANGE
The operating range may be adjusted according to the intended purpose. However, it does depend on conditions. Adjustment is carried out by means of “aerial link wires” on the circuit panels. With all these in place, the range of the prototype exceeds 12 metres in open air. It will also work throughout several rooms indoors if required. If the battery voltage in either transmit- ter or receiver falls below a certain value, or if a transmitter is switched off, a buzzer will sound. The specified batteries in the transmitters should provide several hun- dred hours of operation. Those in the receiver should provide around 100 hours.

PERSONAL CODE
The EPE Minder uses a system of digitally encoded low-power radio signals,
which pass from the transmitters to the receiver. The code is different for each transmitter so that the receiver is able to distinguish one from the other. Type-approved, pre-aligned transmitter and receiver modules that operate at 433MHz. are used. No traditional “radio” skills are needed and no licence is needed for their use in the UK.

TRANSMITTER CIRCUIT
The circuit diagram for a single trans- mitter unit is shown in Fig.1. Current is
supplied to the circuit from a 3V “coin” cell, B1, via on-off switch S2 and diode D1. The diode provides reverse-polarity protection. It is best to use the specified Schottky device which introduces a smaller forward voltage drop, and therefore less loss, than a conventional silicon diode (0·2V rather than 0·7V approximately). Capacitor C2 provides a small reserve of energy and pre- vents the supply voltage from fluctuating. This stabilises operation. A low power 7555 timer, IC1, is set up in a standard astable (pulse generator) con- figuration. While switched on, this produces a continuous train of on-off pulses at its output, pin 3.The choice of resistors R1, R2 and capacitor C1 provide one pulse per second for one of the transmitters (Unit A) and one pulse every 1·2 seconds for the other one (Unit B). In fact, the timings are slightly longer but it helps to consider them as above. Also, the on times are much longer than the off ones in each case. The purpose of this will be explained presently.




RECEIVER CIRCUIT

Receiver module, IC1, requires a supply of between 4·5V and 5·5V. The 6V nomi-
nal battery pack, B1, is brought within range by the forward drop of diode D5
(0·7V approx.) This diode also provides reverse-polarity protection. Capacitor C4 charges up and provides a small reserve of energy. This will be useful when the battery is nearing the end of its operating life. When the supply voltage falls below some 4V, the receiver stops working and the buzzer will sound. Below around 3V, the buzzer itself will not operate so it is important to check operation each time the units are used. Receiver IC1 should be of the a.m. (amplitude modulation) type as specified in the components list. As such, it will respond to the on-off pulses provided by the transmitter. The inexpensive super regenerative (rather than superhet) variety will be perfectly adequate. The low-power variants of these receivers have not been tested. Although for battery operation they would appear to be ideal, the standard type is more readily available.

The receiver may be considered as hav- ing separate r.f. (radio frequency) and a.f. (audio frequency) sections. These have individual supply inputs (pins 1, 10, 12 and 15 with some being duplicated). These are all connected together and decoupled using capacitor C1.

TESTING

Having completed the Receiver board, we can now commence testing all three
boards. It helps to minimise the Receiver “hold-off” time by adjusting preset VR1 fully anti-clockwise (as viewed from the left-hand side of the p.c.b.) and preset VR2 fully clockwise (as viewed from the right- hand side of the p.c.b.). Check that the Test link has been left unconnected to prevent IC4b signal from passing to transistor TR1’s base. Switch on Single Channel switch S3 so that Channel A is enabled. With On-Off switch S4 off, insert the batteries. Switch on. After a short delay, the buzzer WD1 should sound. Now place Transmitter A approximately
three metres away from the Receiver, insert the battery and switch on. The buzzer should begin to bleep every second. The same procedure is now repeated for Transmitter B. To do this, switch S3 off to disable Channel A and firmly twist together the ends of the Test link wires. It is not advisable to solder this connection unless the i.c.s are removed first. The buzzer should bleep at a slightly slower rate than for Transmitter A. It is unlikely that the time periods of the two transmitters will be the same (due to overlapping component tolerances).
However, if they are, one of them will need to be changed. Choose slightly higher values for resistors R1 and R2 to slow it down and vice versa. Remove the i.c.s before making any modifications.

HOLD-OFF TIME
When both transmitters have been test- ed, switch S3 on to enable both channels. presets VR1 and VR2 should now be adjusted to approximately mid-track posi- tion. This should provide a sufficient “hold off” time plus a small margin. The buzzer should now remain off and only sound when one of the transmitters is switched off or moved out of range. Leave them operating for several minutes. If the occasional spurious bleep is heard, increase the settings of VR1/VR2 to pre- vent this happening.

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NE555 IC Timer

The 555 Timer is an integrated circuit (chip) implementing a variety of timer and multivibrator applications. The IC was designed and invented by Hans R. Camenzind. It was designed in 1970 and introduced in 1971 by Signetics (later acquired by Philips). The original name was the SE555/NE555 and was called "The IC Time Machine".

The 555 gets its name from the three 5-k Ohm resistors used in typical early implementations. It is still in wide use, thanks to its ease of use, low price and good stability. As of 2003[update], 1 billion units are manufactured every year.

The 555 timer is one of the most popular and versatile integrated circuits ever produced. It includes 23 transistors, 2 diodes and 16 resistors on a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8).

The 555 has three operating modes:

* Monostable mode: in this mode, the 555 functions as a "one-shot". Applications include timers, missing pulse detection, bouncefree switches, touch switches, Frequency Divider,Capacitance Measurement, Pulse Width Modulation (PWM) etc

* Astable - Free Running mode: the 555 can operate as an oscillator. Uses include LED and lamp flashers, pulse generation, logic clocks, tone generation, security alarms, pulse position modulation, etc.

* Bistable mode or Schmitt trigger: the 555 can operate as a flip-flop, if the DIS pin is not connected and no capacitor is used. Uses include bouncefree latched switches, etc.

The connection of the pins is as follows:

Nr. Name Purpose

1 GND Ground, low level (0V)

2 TR A short pulse high → low on the trigger starts the timer

3 Q During a timing interval, the output stays at +VCC

4 R A timing interval can be interrupted by applying a reset pulse to low (0V)

5 CV Control voltage allows access to the internal voltage divider (2/3 VCC)

6 THR The threshold at which the interval ends (it ends if U.thr → 2/3 VCC)

7 DIS Connected to a capacitor whose discharge time will influence the timing interval

8 V+, VCC The positive supply voltage which must be between 3 and 15 V

In the astable mode, the high time from each pulse is given by

high = 0.693.(R1 + R2).C

and the low time from each pulse is given by

low = 0.693.R2.C

where R1 and R2 are the values of the resistors in ohms and C is the value of the capacitor in farads.

Specifications

These specifications apply to the NE555. Other 555 timers can have better specifications depending on the grade (military, medical, etc).

* Supply voltage (VCC) 4.5 to 15 V

* Supply current (VCC = +5 V) 3 to 6 mA

* Supply current (VCC = +15 V) 10 to 15 mA

* Output current (maximum) 200 mA

* Power dissipation 600 mW

* Operating temperature 0 to 70 °C

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AT89C2051 microcontroller circuit

Real time controller AT89C2051

Real time controller is a device used to exercise control over household device continuously ongoing and scheduled. The series of Real Time Controllers with microcontroller AT89C2051 which dituls in this article is a tool that can do that serve targeted. The series of Real Time Controller with Microcontroller AT89C2051 Atmel AT89C2051 uses a data processor and controller as device installed. 

In the application directly devices requires a separate interface from a wide range of Real Time Controllers with this AT89C2051 microcontroller. When will connect the device with the AC power source to use interface optocoupler (MOC) or solid state relay. Devices that can be connected with the series of Real Time Controller with Microcontroller AT89C2051 include lights, water machines, fans, electronic gate. The series of Real Time Controllers with this AT89C2051 microcontroller to control a height of water level, controlling the flame lights the scheduled SCARA and censored.

Specifications Series Real Time Controller with AT89C2051 Microcontroller

The series of Real Time Controller with Microcontroller AT89C2051 uses a computer to perform serial communication settings via computer. The series of Real Time Controller with Microcontroller AT89C2051 has 6 units of output channels that can be independently controlled depending on the program induced in the tool. Output in the series of Real Time Controller with AT89C2051 microcontroller requires an interface to deal with equipment that will be in control.

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Toggle switch with Infra Red IR

Toggle switch in this article is a series of toggle switches that are controlled by infrared light. The series toggle switch is made from a combination of data flip-flop CD4013 2 units. Receiver circuit of the infrared light signals arranged with infrared receiver as found on television remote receiver. Infrared signal from remote is used as clock signals and data to the data flip-flop first. then the second flip-flop data set as a toggle flip-flop toggle the output signal is used to drive the relay. for more details can be seen in thethe following image .

Series Toggle Switch With Infra Red (IR) that is required to supply voltage range of 12VDC and the output of Toggle Switch With Infra Red (IR) is dapt used to turn on the lights or other electronic devices with DC or AC voltage source. Series Toggle Switch With Infra Red (IR) was isolated from the load that is placed for use as the final relay.

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