18W Car Stereo Amplifier Rise

This automobile stereo amplifier project is a class AB audio power amplifier using the Hitachi HA13118 module. It not only can be used in automobile application but also in any transportable or home amplifier process. It is simple to construct & has a maximum of outside parts. The module has a high power output from a low voltage supply using the bridge tied load system, & a high gain of 55dB.

This project will be useful in applications where the input signal is a low level, without requiring the use of a separate pre-amplifier. This IC module has a built in surge protection circuit, thermal shutdown circuit, ground fault protection circuit & power supply fault protection circuit making it reliable.

The Specifications of this project 
D.C. Input : 8 – 18V at 1-2 A

Power output : 18W maximum, 4 ohm load, 18V DC supply

S/N ratio : > 70 dB

THD : < 0.2% @ 1W

Freq. Response : ~ 30 Hz to 30 kHz, –3 dB

Input level : < 25 mV, for full output (G > 50dB)

Input Impedance : ~ 30 k ohm

The supply voltage necessary for this project is 8 -18V DC, at least one to two Amps. Maximum output power will only be obtained with a power supply of 18V at greater than two A, using a four ohm speaker. The power supply ought to be well filtered to reduce mains hum, a regulated supply will reduce noise even further. Additional filtering is unnecessary if operating from a battery supply.

Circuit Diagram Description

Most of the circuitry is contained within the amplifier module. C10 is the input coupling capacitor and blocks DC from the input. C11 bypasses any RF which may be present at the input. C1 & C2 provide an AC ground for the inverting inputs of the IC. R1/C7 and R2/C8 provide a high frequency load for stability with difficult speakers. C five & C six provide bootstrap feedback for the IC. C9 & C12 provide power supply filtering.

An externally mounted logarithmic potentiometer of between 10k ohm and 50k ohm, is used depending on the desired input impedance. The impedance ought to be keep as high as feasible for a guitar amp, unless using a separate pre-amp. Make sure-that the heat sink is mounted to the module.

Read More..

High Power Car Battary Eliminator

To operate car audio (or video) system from household 230V AC mains supply, you need a DC adaptor. DC adaptors available in the market are generally costly and supply an unregulated DC. To overcome these problems, an economical and reliable circuit of a high-power, regulated DC adaptor using reasonably low number of components is presented here.  Transformer X1 steps down 230V AC mains supply to around 30V AC, which is then rectified by a bridge rectifier comprising 5406 rectifier diodes D1 through D4. The rectified pulsating DC is smoothed by two 4700μF filter capacitors C1 and C2. The next part of the circuit is a seriestransistor regulator circuit realised using high-power transistor 2N3773 (T1).

 

Fixed-base reference for the transistor is taken from the output pin of 3-pin regulator IC1 (LM 7806). The normal output of IC1 is raised to about 13.8 volts by suitably biasing its common terminal by components ZD1 and LED1. This simple arrangement provides good, stable voltcuit age reference at a low cost. LED1 also works as an output indicator.Finally, a crowbar-type protection circuit is added. If the output voltage exceeds 15V due to some reason such as component failure, the SCR fires because of the breakdown of zener ZD2. Once SCR fires, it presents a short-circuit across the unregulated DC supply, resulting in the blowing of fuse F1 instantly. This offers guaranteed protection to the equipment connected and to the circuit itself.

 

This circuit can be assembled using a small general-purpose PCB. A goodquality heat-sink is required for transistor T1. Enclose the complete circuit in a readymade big adaptor cabinet as shown in the figure.

Source:  http://www.ecircuitslab.com/2011/09/high-power-car-battary-eliminator.html

Read More..

Simple But Reliable Car Battery Tester

This circuit uses the popular and easy to find LM3914 IC. This IC is very simple to drive, needs no voltage regulators (it has a built in voltage regulator) and can be powered from almost every source. This circuit is very easy to explain: When the test button is pressed, the Car battery voltage is feed into a high impedance voltage divider. His purpose is to divide 12V to 1,25V (or lower values to lower values).

This solution is better than letting the internal voltage regulator set the 12V sample voltage to be feed into the internal voltage divider simply because it cannot regulate 12V when the voltage drops lower (linear regulators only step down). Simply wiring with no adjust, the regulator provides stable 1,25V which is fed into the precision internal resistor cascade to generate sample voltages for the internal comparators. Anyway the default setting let you to measure voltages between 8 and 12V but you can measure even from 0V to 12V setting the offset trimmer to 0 (but i think that under 9 volt your car would not start).

 Car Battery Tester  Circuit diagram:

There is a smoothing capacitor (4700uF 16V) it is used to adsorb EMF noise produced from the ignition coil if you are measuring the battery during the engine working. Diesel engines would not need it, but Im not sure. If you like more a point graph rather than a bar graph simply disconnect pin 9 on the IC (MODE) from power. The calculations are simple (default)
For the first comparator the voltage is : 0,833 V corresponding to 8 V
* * * * * voltage is : 0,875 V corresponding to 8,4 V
for the last comparator the voltage is : 1,25 V corresponding to 12 V
Have fun, learn and dont let you car battery discharge... ;-)

author: Jonathan Filippi
e-mail: jonathan.filippi@virgilio.it

Read More..

Car Mobile Phone Charger Circuit

Cellphone battery charging process when were done traveling is a big problem. Because when traveling source of power supply is generally difficult to find. If you turn on your phone then the battery continuously over time will run out within a period of five to six hours and eventually mobile phones unusable. Here is described a series of simple charger that will increase battery life two to three hours.

In principle, the charger uses a series of Limited Voltage Current Source. Generally requires cellphone battery voltage 3.6 - 6 volts DC and currents 180-200 mA to perform the charging process. Cellphone battery usually consists of three NiCd battery cells, and each cell has a voltage of 1.2 volts potential. At the speed - average low flows required to charge mobile phone battery about - about 100mA.

In this series there is a 12V voltage source consists of 8 regular battery cells (each cell 1.5 Volt) able to supply current at 1.8 A which is connected with output terminals.

The circuit is also able to monitor the battery voltage level which is in charge. And will automatically cut off the charging process when the output terminal detects a certain battery voltage level predetermined. Timer IC NE555 is used to charge and monitor the voltage level in the battery, Pin 5 (IC1) as the control voltage using a reference voltage zener voltage 5.6Volt. Voltage at Pin 6 as the threshold set by VR1 and the voltage at Pin 2 as the trigger is set by VR2.

When the cellphone battery is connected in series (the Charging Process) applied voltage on PIN2 (IC1) as a trigger would be below the value 1 / 3 Vcc and will cause the Flip-Flop in IC1 will ON and on Pin 3 (IC1) will be high (Cause transistor T1 saturation.). When the battery is full (Full Charge) then the voltage will rise and the voltage on the PIN2 (IC1) will be above the level of trigger point threshold. This will cause the Flip Flop OFF and the output will be low (transistor T1 causes the cutoff) and indirectly also the charging process will stop.

Pin 6 (Threshold IC1) is set at 2 / 3 Vcc by using VR1, transistors T1 which is used to increase the charging current. R3 value is very important to provide the charging current, by setting the value of R3 to 39 ohms then the charging current supplied approximately 180mA. This circuit can be built on any type of PCB (General Purpose PCB) for the calibration process using the DC voltage level cutoff Variable Power Supply. Connect the output terminal circuit with Variable DC Power Supply and set on 7 volts. Adjust VR1 in middle position and slowly adjust VR2 until LED1 OFF, this indicates Low Output. LED1 should turn on when the DC Variable Power Supply voltage is reduced below 5V. LED1 Status flame shown in the table below. Closed circuit with plastic casing and use a suitable connector for connecting to the Battery for Mobile.

Read More..

Car Battery 12v Charger

The usual chargers of battery automotive, are simple and cheap appliances that charge continuously the battery, with a rythm of few amperes, for the time where the appliance is ON. If the holder do not close in time the charger, the battery will overcharge and her electrolytic faculty are lost with evaporation or likely exists destruction of her elements. The charger of circuit exceeds these faults. It checks electronic the situation of charge of battery and it has circuit of control with retroaction, that forces the battery charge with biggest rythm until charge completely. 

 

Circuit diagram:

Car Battery 12v Charger Circuit Diaram

When charge completely, it turns on one RED led (LD2). The charger has been drawn in order to charge batteries of 12V, ONLY. What should watch it from what it manufactures the circuit, they are the cables that connect the transformer with the circuit and in the continuity the battery, should they are big cross-section, so that heat when it passes from in them the current of charge and also they do not cause fall of voltage at the way of current through them.

Adjustment

After assembling of the circuit, adjust TR1 to null value, power-up and make the following adjustments :-

1. Without connecting the battery check that the 2 LED?s are turned on.
2. Connect a car battery to the circuit and check that LD2 is OFF and a current (normally 2A to 4A) is flowing to the battery.
3. Adjust TR1 until LD2 turns ON and the charge current is cut.
4. Adjust TR1 to null value and charge the battery using the hydrometer technique (if you do not have or do not know how to use a hydrometer, then use a good condition battery and charge).

Carefully adjust TR1 so that LD2 begins to turn ON and the charge current falls to a few hundred milliamps (mA). If TR1 is set correctly then in the next round of charging you will noticed LD2 begin to flicker as the battery is being charged. When battery is completely charged, LD2 turns ON completely.TR1 does not need further adjustment anymore. Q1 is connected in line with the battery and is fired by R3, R4 and LD2. The R2, C1, TR1 and D2 sense the voltage of the battery terminal and activate Q2 when the voltage of the battery terminal exceeds the value predetermined by TR1.

When an uncharged battery is connected, the terminal voltage is low. Under this circumstance, Q2 is turned OFF and Q1 is fired in each half cycle by R3, R4 and LD2. The Q1 functions as a simple rectifier and charges the battery. If the battery terminal voltage is increased above the level that had been fixed by TR1, then Q2 shifts the control of Q1 gate. This deactivates Q1 and cuts off the current supply to the battery and turns LD2 ON indicating that the charge has been completed. Q1 and bridge rectifier GR1 should be mounted on heatsinks to prevent overheating. M1 is a 5A DC ammeter to measure the charge current.

Source :users.otenet.gr

Read More..

SW Converter for Digital AM Car Radio

This circuit is purposely offered with many bathroomse ends (not actually, of course) to stimulate experimenting with RF circuitry at a small outlay. Looking at the circuit diagram you could additionally recognize a modified model of the SW Converter for AM Radios described in different situations in that issue. The changes had been necessary to make the circuit compatible with a digital quite than analogue AM car radio. The main distinction between digital AM radios and their all-analogue predecessors is that tuning is in 9 kHz (some-times 4.5 kHz steps) in compliance with the international frequency allocation for the band. Obviously, that exact step dimension, fascinating as it can be on MW, is a stumbling block if you want to use a digital AM receiver together with a frequency step-up converter for SW, where chaos reigns and there isn't any fastened step dimension. The first try was once to make the crystal oscillator variable through about 5 kHz each and every approach.

 

Circuit diagram :

SW Converter for Digital AM Car Radio Circuit Diagram

 

Unfortunately, regardless of serious efforts, the crystal could not be pulled more than 1 or 2 kHz so some different resolution had to be found. After finding out the NE/SA602/612 informationsheet, it was once found that a variable LC based totally oscillator was once one of the best different. The circuit labored after winding a resonant LC circuit and including a zero.1 µF sequence capacitor to dam the DC element on pin 6 of the NE602 (612). When the tuning used to be found to be a bit sharp with the original capacitor, a simple bandspread (or advantageous tuning) characteristic used to be added via shunting the LC resonant circuit with a lightly loaded 365 pF tuning capacitor (C10) which, like the principle tuning counterpart, C8, was once ratted from an outdated transistor radio. The tuning coil, L1, consists of 8 to 10 turns of 0.6-0.8mm dia. enamelled copper wire (ECW) on a 6-8 mm dia. former with out a core. With this coil, frequency protection shall be from about 4 MHz to 12 MHz or so. Details on Tr1 may be discovered in the referring article.

 

Note that no tuning capacitor is used on the secondary — the input stray capacitance of the NE602 (612) does the trick. A BFO (beat frequency oscillator) was once delivered to let SSB (single sideband) signals to be received. The BFO built round T1 is inconspicuous, has a heap of output and that is steady enough to automobilery an SSB signal for a few minutes with out adjustment. The BFO frequency is tuned with C3. Tr2 is a ready-made four55 kHz IF transformer whose inner capacitor was once first crushed after which eliminated with pliers. When S2 is closed the BFO output sign is solely superimposed on the NE602 (612) IF output to the MW radio. The converter will have to be built into a steel box for shielding. If you in finding that the BFO provides too much output, disconnect it as steered in the circuit diagram and let stray coupling do the work. Sensitivity, even on a 1-metre size of automotive radio aerial, is quite superb. Bearing in mind that many of the main international SW broadcasting stations like Radio NHK Japan, Moscow, BBC and many others.) generate enough power to ensure that you are going to hear them, it's nonetheless kind of thrilling to pay attention to such signals for the first time in your automobile radio. 

http://www.ecircuitslab.com/2012/02/sw-converter-for-digital-am-car-radio.html

Read More..

Car Reversing Horn with Flasher

Here is a simple circuit that starts playing the car horn whenever your car is in reverse gear. The circuit (refer Fig. 1) employs dual timer NE556 to generate the sound. One of the timers is wired as an astable multivibrator to generate the tone and the other is wired as a monostable multivibrator.

Circuit diagram :
 

Fig. 1: Car reverse horn Circuit Diagram

Working of the circuit is simple. When the car is in reverse gear, reverse-gear switch S1 of the car gets shorted and the monostable timer triggers to give a high output. As a result, the junction of diodes D1 and D2 goes high for a few seconds depending on the time period developed through resistor R4 and capacitor C4. At this point, the astable multivibrator is enabled to start oscillating. The output of the astable multivibrator is fed to the speaker through capacitor C6. The speaker, in turn, produces sound until the output of the monostable is high.

When the junction of diodes D1 and D2 is low, the astable multivibrator is disabled to stop oscillating. The output of the astable multivibrator is fed to the speaker through capacitor C6. The speaker, in turn, does not produce sound.

Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. Connect the circuit to the car reverse switch through two wires such that S1 shorts when the car gear is reversed and is open otherwise. To power the circuit, use the car battery.

The flasher circuit (shown in Fig. 2) is built around timer NE555, which is wired as an astable multivibrator that outputs square wave at its pin 3. A 10W auto bulb is used for flasher. The flashing rate of the bulb is decided by preset VR1.

Fig. 2: Flasher Circuit Diagram

Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. The flasher bulb can be mounted at the cars rear side in a reflector or a narrow painted suitable enclosure.

EFY note. A higher-wattage bulb may reduce the intensity of the headlight. You can enclose both the car-reversing horn and flasher circuits together or separately in a cabinet in your car.

Source :  http://www.ecircuitslab.com/2011/06/car-reversing-horn-with-flasher.html

Read More..