Showing posts with label based. Show all posts
Showing posts with label based. Show all posts
Monday, November 17, 2014
LM3914 IC based on Simple Battery Tester
This LM3914 IC based on Simple Battery Tester is very simple to explain:
Once the test switch is pushed, the Car battery voltage is supply into a high impedance voltage divider. His function is to divide 12V to 1, 25V (or lower values to reduced values). This solution is much better than enabling the internal voltage regulator set the 12V sample voltage to be feed into the internal voltage divider simply because it cannot regulate 12V if the voltage falls lower (linear regulators only step down). Simply wiring with no change, the regulator provides secure 1, 25V which can be fed into the precision internal resistor cascade to create sample voltages to the internal comparators.
In any case the default establishing let you to determine voltages between 8 and 12V however you can measure even from 0V to 12V setting the offset trimmer to 0 (but i believe that below 9 volt your vehicle would not start). There is a smoothing capacitor (4700uF 16V) it is used to adsorb EMF noises produced from the ignition coil if youre testing the battery during the engine working. Diesel engines would not need it, but i am not sure. If you want more a level graph rather than a bar graph simply disconnect pin 9 on the IC (MODE) from power. The calculations are usually simple (default).
Saturday, October 18, 2014
Atmel based Sony Unilink
Atmel based Sony Unilink
The Sony Unilink protocol is usually meant to control the CD-player of an automobile and can also perform other various tasks. The Sony Unilink protocol can be used to connect other auxiliary devices to your car stereo (these devices vary from CD shuttles to iPods).
This project is an AVR Sony Unilink interface based on the Atmel ATmega8 microcontroller. The MCU runs at 7,3728MHz and the communication with the Unilink bus is made through Serial Peripheral Interface (SPI) and the software supports RS232 input and output.
Wednesday, October 15, 2014
Build a 10 LED Bar Dot VU Meter Circuit based LM3915
Build a 10 LED Bar Dot VU meter circuit based LM3915. It differs in many respects from other applications on the same chip. The circuit is intended for those who want a VU meter that is connected directly to the output of an power amplifier.
10 LED Bar Dot VU Meter Circuit based LM3915 Circuit Diagram
It’s possible to adjust the sensitivity to work with amplifiers that have different output power, you just need to change the value of R1 according to Table 1. In case you did’n find the exact resistor value, then choose the next standard value (for example if you cannot find 33K ohm, then find the 36K ohm), or if you want maximum accuracy you need to put resistors in series or in parallel to achieve the correct value.
You can use various types of LEDs (round or square) to get the visual and aesthetic result you want. The switch S1 will allow you to choose whether VU meter will work as a bar or one by one (dot). In position ON [closed switch], the LED operation is Bar, while in position OFF [open switch], the LED operate in Dot. In Bar mode, the power consumption rises because all of the LED will be work and can reach up to 150mA.
For amplifier with two channels is obvious that we should build two identical circuits, one for each channel. The operating voltage of the circuit is +12 V. Taking this trend should be done by the tendency of the amp. Usually amps work with voltages which higher than +12 Volts for the circuit. For this reason, we must added a component which can decrease, regulate and stabilize the +Vp voltage at +12 Volts. The component we are used is IC2 (LM317) which is an adjustable voltage regulator and stabilizer.
Using a small brushing is necessary because the differences in the potential entry; output is large so that we develop high levels of temperature. The use of R5 helps in voltage drop to descend the voltage at the input of IC2 at lower levels. The calculation of this resistance is more empirically using Ohm’s law. The voltage at the input of IC2 must be higher than +16 Volts. For example, if the voltage of the amplifier is +50 Volts, we should have a voltage drop 50-16 = 34 Volts on the resistance R5. For the electric current, 50mA average is needed by the circuit [may be up to 150mA], the value of R5 = V / I = 34/0.05 = 680 ohms 2W. You may need to increase or decrease this value by trials. Because the resistor is going to heat up, then it will be better to put some distance from the PCB.
It will be better to set up and measure the output vltage of the IC2 by adjusting TR1 first, you need yo remove IC1 to secure the IC1. If you are able to supply the stabilized +12 V from somewhere in the amplifier circuit, then you’ll need to remove the R5, the IC2 and materials inside the dotted line.
PCB layout design:
Friday, September 12, 2014
Audio power amplifier circuit based on TDA4920 TDA4925 TDA4930
Specification :
This is stereo amplifier , based on IC TDA4920 , TDA4925 , TDA4930 . Minimum voltage require 9 volts and maximum voltage 13 volts . Maximum power output 2 x 15 Watts with 4 Ohms impedance. Quiescent current 30 mA. See audio circuit scheematic below :
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