Monday, March 29, 2010

Acceleration Meter For Cars

The circuit is drawn for measurement of acceleration from –1000 mg until + 1000 mg. It can be placed in kantra'n the car and be supplied from the sheath of electric lighter. The circuit includes one indicative LED and a screen LCD.

The connections for ADXL202.

The shematic diagram of the circuit.

The measurement of acceleration becomes with the use of IC from Analog Devices, the ADXL202. The particular element contains 2 autonomous vertical between them sensors, for the measurement in two axes. For the particular application becomes use of only it's one. Acceleration meter measures dynamic or static acceleration from –2g until 2g (where g is the acceleration of gravity) and when this is equal to zero, exit is a signal PWM, with Duty Cycle 50%. As long as the acceleration increases, increases also the Duty Cycle, with biggest response the 75% (in the 2g), while for acceleration –2g, the Duty Cycle is 25%. As conclusion from more, has that for change 1g, is altered also the Duty Cycle of exit at 12,5%.

The measurement of Duty Cycle of response of acceleration meter becomes with the help of Timer1 (16 bit). The period of signal of expense, has been fixed in the 1,12 msec. The frequency of oscillation of microcontroller is in the 3,6864 MHz and this means that it's each circle of access lasts 0,27 * 10 -6 sec. Using timer1, in frequency of measurement ck/1, the biggest feasible counted time is the 65536 * 0.27 * 10 -3 msec = 17.778 msec, which is bigger than period (1,12 msec). So, any price Duty Cycle it is possible to be measured.

Before the beginning of measurements, it precedes a process of accelerator’s initializing. At this process it is doing 16 measurements, and then is found their mean. In short time interval, it is considered that the acceleration was not altered also thus the result, us gives the point of null acceleration. In other words at this process becomes approach of value Duty Cycle, that corresponds in null acceleration. From now on, after each measurement, it will be removed from Duty Cycle, the null acceleration.

At the placement of appliance, the completed ADXL202 should be always parallel with the surface of ground and the pins 1 and 14 they see front part of car. The LCD is connected at the K2 connector and the ADXL202 is connected at the K1 connector (K3 is connected with K1).


With the shooting of switch of starter, the circuit is supplied. In the beginning, and as long as LED is power-off, becomes initializing of meter. Acceleration meter is will be always placed so as to it measures the acceleration at the address of movement of vehicle. As long as however well and it is placed this, will always exist a component vertical in the movement and with time to the centre of ground. This component is the acceleration of gravity and which is always removed from each measurement. As soon as the LED turns on (in minimal time), then the initializing it has become. From now on the meter measures the acceleration and him presents in the screen. When is presented the symbol "-", it means that it is deceleration.

In the above department of screen is presented the clue of total time interval, that your car is in operation. The operation of this clock is based on vibrations that come in the pin External Interrupt 0, from exterior circuit based in the timer LM555.

In the future it is is published new circuit, with the himself characteristically, that will use the second exit acceleration meter, for the measurement of centripetal acceleration, at the movement of car.

Download the source code, Hex file and schematic diagram of this circuit.

Download the manual of ADXL202.

Solar NiCad Charger

The MAX639 has its own current limiter build in, set for 200mA. Plenty! Make sure that the charging NiCads can handle the continuous current of 200mA, for example, NiCad battery packs of 1700+ mA used for R/C (Radio Control) cars and electric aircraft.

Parts List:
R1 = 820K, 1%
R2,R3 = 75K, 1%
R4 = 1M, 5%
D1,D2 = 1N5817, Schottky diode, or NTE585
L1 = 100uH, coil
U1 = MAX639, integrated circuit
C1 = 100uF/40V, Electrolytic capacitor
C2 = 47uF/40V, Electrolytic capacitor


In this project the robot, is controlled by a mobile phone that makes call to the mobile phone attached to the robot in the course of the call, if any button is pressed control
corresponding to the button pressed is heard at the other end of the call. This tone is called dual tone multi frequency tome (DTMF) robot receives this DTMF tone with
the help of phone stacked in the robot The received tone is processed by the

atmega16 or atemega32 microcontroller with the help of DTMF decoder MT8870 the decoder decodes the
DTMF tone in to its equivalent binary digit and this binary number is send to the microcontroller, the microcontroller is preprogrammed to take a decision for any give input
and outputs its decision to motor drivers in order to drive the motors for forward or backward motion or a turn. The mobile that makes a call to the mobile phone stacked
in the robot acts as a remote. So this simple robotic project does not require the construction ofreceiver and transmitter units. DTMF signaling is used for telephone
signaling over the line in the voice frequency band to the call switching center. The version of DTMF used for telephone dialing is known as touch tone. DTMF assigns a
specific frequency (consisting of two separate tones) to each key s that it can easily be identified by the electronic circuit. The signal generated by the DTMF encoder is
the direct al-gebric submission, in real time of the amplitudes of two sine(cosine) waves of different frequencies, i.e. ,pressing 5 will send a tone made by adding 1336hz
and 770hz to the other end of the mobile. The tones and assignments in a dtmf system shown below

Click on the image to Enlarge

Click on the image to Enlarge


Friday, March 26, 2010

Introduction H-Bridge

For car makers the first robot tip of the spear is a robot car that drives the movement of a robot car.
If the car was a robot can walk and do not have logic or pemrogramman hit here and there, directly exhibited to temen-temen others while dashing waist, felt the professor.
(sometimes need to let the spirit of continued learning and other friens interested in learning).

In this section you should be serious because the DC motor driver is a major, often corrupt, and often damage other electronic systems. If you can not make a DC motor driver good and stable so jgn make more complex robots.
Usually complex robot dizzy on programming algorithm compared to electronic circuits.

Serious intention of need patience, a lot of searching for information, understand the concept of the circuit, in the event of damage to create a new lgs jgn but find the cause of the damage and analysis.

DC motor election up to you but I recommend a large torque and enough speed requires adequate supply (12 VDC or 24 VDC.)

The design of H-Bridge DC motor driver can be done in 4 ways:
1. Using Relay DC.
2. Using the transistor.
3. Relay and transistor combination.
4. Using the IC.

Of the four ways above each have advantages and disadvantages and designers should be able to choose and use the appropriate one based on the design.
I will explain the basic principle of the H-Bridge.

Suppose we make the H-Bridge uses 4 common fruits such as toggle switches 1 and setting the image of On-Off switch manually. In order for a DC motor can be spun so one must be given SUPPLY terminals and other terminals GND or in other words there should be 2 switches are ON and the other 2 switches must be OFF. The flow of currents and voltages look like in figure 1.
If you want a DC motor is rotated to the RIGHT terminal 1 and 4 whereas ON OFF 2 and 3, on the other hand if a DC motor to be played to the LEFT the terminals 1 and 4 whereas OFF ON 2 and 3.

Different from Figure 2 that only uses 2 switches but the principle is the same.
If you want to stop the motor switch 1 and switch condition A 2 condition C or condition of the switch 1 switch 2 B and D conditions (the two motor terminals have no potential difference).
If the motor to spin kekanan switch 1 and switch condition A 2 condition D. If the motor wants to turn left switch 1 and switch condition B 2 C. The conditions

From this picture the H-Bridge is only set to be given polarity on a DC motor to spin 2-way (return).

For certain applications such as motor control that have current and large voltage,
so as not to damage the controller circuit, DC motor circuit and the controller must be separated
(supply and ground separately) to use such components Optoisolator or relay.

Oh yeah almost forgot the H-Bridge can be used to control motor Bipolar STEPPER
but I do not discuss further.

H-Bridge Transistor & Relay

Relay form of mechanical switches can be passed large current and voltage but it can not use PWM and the transistor can use PWM but the current and voltage limited. For some reason or particular needs (I also do not really know what reason) then the combination of relay and transistor can be done to make the H-Bridge.

Figure 1 is a combination circuit and transistor relays in H-Bridge, the left side consists of PNP and NPN transistor, while the right side of the fruit relay 1. Schematiknya circuits, the use of type and type of transistor in accordance with specifications based on the needs of a DC motor that will be controlled. Control relay with enough logic 0 or 1 and the transistor can be applied to PWM with a frequency maximum PWM frequency transistors.

In this series should use the 3 pins on the microcontroller port 1 for NPN transistors, PNP transistors to 1, and 1 for the relay. In contrast to earlier can be simplified to just 2 pins only. PWM applied to the transistor PNP or NPN transistor while the relay berlogika 1 or 0 by default conditions (NC) should contact the Ground.

H-Bridge IC

Makes H-Bridge using IC often applied to the robot cars because the small size, easy to use, compatible with the microcontroller ports, and can be implemented using a PWM with a high frequency.
In fruit IC 1 has been able to control the DC motor 2 so that the fruit is more appropriate IC for use in automobile applications robots that I will describe later.
I will only discuss H-Bridge using IC L293 and L298.

IC L293

There are 2 types of IC L293 that I know of L293 and L293D, the difference is
a. L293 maximum current is 1 A L293D whereas the maximum current of 600 mA
b. L293 does not have an internal diode while the L293D has an internal diode.

From the data above, if you control the flow of a DC motor with less than 600 mA for L293D then use have an internal diode which means no need to add additional diode circuit. But if the current over 600 mA and then use L293 external diode should be added that will protect the IC from damage.
I will only discuss the IC L293 because the same principle but the current L293D greater.

Schematik circuit in Figure 1 is a series of half of the control L293 IC 1 fruit with a series DC motor H-Bridge. Setting the direction of DC motor with the mengimplemetasikan logic IC pins as shown in the table L293 image 1.

Schematik circuit in Figure 2 is a circuit controlling a DC motor 2 pieces of M1 and M2. Implementation of the motor as shown in table 2 images.
Do not forget to vote diode specifications must have the Recovery time is faster than the time switching IC. L293 IC time for the transition (Transition Time, Low to high output and high level to low level of output) is 300 ns so Fast Recovery Diode trr <= 300 ns. I use a 1N4942 type diode recovery time to 150 ns.

IC L298

Schematik circuit in Figure 3 is a series of half of the control L298 IC 1 fruit with a series DC motor H-Bridge. Setting the direction of DC motor with the mengimplemetasikan logic IC pins as shown in the table L298 picture 3. DC motor motion settings will be discussed at ---------- ROBOT.

If you notice on the L298 datasheet there is a sense resistor (RS) which are placed before ground. This resistor serves to "touch" (sense) current flows in the H-Bridge as feedback controllers, and therefore this resistor (RS) are optional that may not be installed.
If you install RS it is the resistor value can not reduce the current flowing in the H-Bridge to the current in DC motor reduced resulting in reduced speed DC motors, DC motors and even not moving at all.
I do not put hospitals because they do not require feedback.

Do not forget to vote diode specifications must have the Recovery time is faster than the time switching IC. L298 IC time for the transition (Transition Time, Low to high output and high level to low level of output) is 200 ns so Fast Recovery Diode trr <= 200 ns. I use a 1N4942 type diode recovery time to 150 ns.

Wednesday, November 4, 2009

Making Read More on Blogger

Simply go to blogger and go with an account you own, clik the link and then go to Layout Edit HTML

To be Ngedit overall template, you must check / mark / switch Expand Widget Templates

This code search } ]]></b:skin> atau ]]></b:skin> to enable basic use your browser's menu to find how to press the keyboard keys Ctrl + F and copy the code in below under the code that the search was.

<b:if cond='data:blog.pageType == "item"'>
span.fullpost {display:inline;}
span.fullpost {display:none;}

Further arranged for the posting cut, look for the code <p><data:post.body/></p> or <data:post.body/> in your template and add the code below right below it:

<b:if cond='data:blog.pageType != "item"'>
<a expr:href='data:post.url'> Read More..</a>

Before you do post copy code below in the menu Setting - Formatting continue to search the bottom of Post Template and copy the following code into it and Save

<span class="fullpost">


and the way posts are: who will be in place tampilakan post above code <span class="fullpost"> and the rest under the code <span class="fullpost"> and in the end with code </span>



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