Thursday, November 13, 2014
LM339 based Grand Prix Starting Lights circuit
This circuit reproduces the starting light sequence currently used by FISA for Formula One racing. It could be used with slot car sets (such as HO scale AFX/Life Like/Tyco sets) or radio controlled cars. IC1, a 555 timer IC, is used as a clock pulse generator. Its output is fed via NAND gates IC2a and IC2c to IC3, a 4024 binary counter. IC2b inverts the O4 output of 4024 binary counter IC3. Initially, IC3 is reset and all its outputs are low, including O4, which causes IC2b to present a logical high to the pin 8 input of IC2c which then passes pulses from the 555 clock circuit to the clock input of the 4024. IC3 then begins counting. After the count has reached binary 1111, the next pulse sends the O4 output of IC3 high, which disables IC2c and IC3 stops counting. The four used outputs of IC3 are connected to a resistor ‘ladder’ which acts as a simple digital to analog convert-er (DAC). As the count increases so does the voltage produced at the top of the ladder and this is connected to the inverting inputs of four comparators inside IC4 (an LM339) and to IC5, which is a 741 op amp also connected as a comparator.
The positive inputs of the comparators are connected to the taps of a voltage divider, with the tapping voltages set using VR1, a 100kO trimpot. As IC3 counts, the rising stepped voltage from the DAC ladder switches the comparators on in sequence, starting with IC4d and working up to IC5. As each comparator is turned on, its pair of LEDs is lit; first LEDs 1 & 2, then LEDs 3 & 4 and so on. When all five pairs of LEDs are lit, the next pulse from IC1 moves the binary count of IC3 to 10000, so the DAC voltage drops back to zero and all LEDs are extinguished. At the same time, counting also stops, because the high on O4 causes IC2c to block further gate pulses. The circuit then remains inactive until the counter is reset by pressing pushbutton switch S1. This allows a new sequence to begin.
Author: David Richards – Copyright: Silicon Chip Electronics
Source:http://www.extremecircuits.net/2010/06/grand-prix-starting-lights_12.html
Tuesday, November 11, 2014
TDA1151 based Motor Speed Controller circuit with explanation
This motor speed controller uses a TDA1151 monolithic integrated circuit , designed by ST Microelectronics . TDA1151 motor speed controller circuit is designed in a SOT-32 plastic package and can be used for small applications where the space inside is very critical .
Also this circuit diagram can be used as speed regulator for DC motors of record players, tape and cassette recorders, movie cameras, toys or other low cost applications.
This speed controller circuit can provide a high output current up to 800 mA without any additional components and has a low quiescent current of 1.7mA .
The TDA1151 require a low reference voltage ( around 1.2 volts ) and it has a excellent parameters stability versus temperature .
The maximum voltage that can be applied to the TDA1151 is around 20 volts .
As you can see in the circuit diagram the TDA1151 require just few common external components and is very easy to design .
Source: electroniq.net
Sunday, September 21, 2014
The evolution of Google TV based on Android completely L
We already knew Google TV, the company system to reach televisions and decoders of our homes. However, the system never made it to be very successful, mainly due to her lack of interest from developers who did not take many applications to this platform. Now, Google announced at its Google I / O 2014 the evolution of the system and now called Android TV.
Unlike Google TV, Android TV would be complemented based on pure Android code L, the new version of the mobile operating system of the company. This would allow developers to easily modify their applications to work directly on this platform, like Android-L (cell phone and tablet) and Android Wear, and not having the need of having to create an entirely new application for this new TV platform.
Currently, a number of applications found on Android and work on the big Lcd TV featuring Android, such as music, games, movies, and more. It is precisely in the area where Android TV game also differs from its predecessor Google TV. Android TV also has a focus on video games, allowing a system is not only television, but also functions as a mini console.
Android TV can be controlled through an Android phone or tablet with L, like a television remote control or video games. In fact, manufacturers are the ones who decide how to offer it in the beginning, is control video game control specially designed for Android TV or regular monitoring of television and users can can choose to use their phones or tablets at any time.
Overall, Android TV interface is very graphical and easy. It works very smoothly and shows you on the home Lcd content recommendations can like, given your history seen or used content, like video games and apps.
Each application has a similar structure where you find a hidden phenomenon on the left side and the other on the right information. The start menu displayed when you open the application and then closes when you enter the information tine each of those categories or play any kind of content.
It has been said that unlike Android mobile phones, Google would control interface and thus offer TV Android experience to users. Thus, manufacturers may not make major changes to the design of Android TV, but if you can add your own content. From now on, the SDK is enabled for developers begin to experience the new Google TV platform and modify or create their applications to be compatible with Android TV.
Saturday, September 6, 2014
1 2Watt Mini Audio Amplifier Circuit based KA2214
This mini audio amplifier schema is based on power IC KA series. This mini amplifier delivers dual audio output (stereo) at 1.2W on each channel.
The KA2214 is a monolithic integrated dual audio power amplifier in a 14-pin plastic dual in line package. It is designed portable audio sets.
Download the KA2214 datasheet for detail features and specifications.
Tuesday, August 12, 2014
PC based Frequency Meter
Here is a simple technique for measuring frequencies over quite a wide frequency range and with acceptable accuracy limits using a PC. It follows the basic technique of measuring low frequencies, i.e. at low frequency, period is measured for a complete wave and frequency is calculated from the measured time-period.
Cascaded binary counters are used for converting the high-frequency signals into low-frequency signals. The parallel port of a computer is used for data input from binary counters. This data is used for measuring time and calculating the frequency of the signal. The block diagram shows the basic connections of the counters and parallel port pin numbers on 25-pin ‘D’ connector of a PC (control register 379 Hex is used for input). External hardware is used only for converting the higher frequency signals into low frequency signals. Thus, the major role in frequency-measurement is played by the software. The PC generates a time-interrupt at a frequency of 18.21 Hz, i.e. after every 54.92 millisecond. Software uses this time-interrupt as a time-reference. The control register of the PC’s parallel port is read and the data is stored continuously in an array for approximately 54.9 ms using a loop. This stored data is then analysed bit-wise. Initially, the higher-order bit (MSB or the seventh-bit) of every array element is scanned for the presence of a complete square wave. If it is found, its time period is measured and if not then the second-highest order bit (sixth bit) is scanned. This operation is performed till the third bit and if no full square wave is still found, an error message is generated which indicates that either there is an error in reading or the frequency signal is lower than 19 Hz. Lower three bits of the control register are not used. When a wave is found, along with its time-period and frequency components, its measurement precision in percentage is also calculated and displayed. Number of data taken in 54.9 ms is also displayed. As stated above, the lower starting range is about 19 Hz. Data is read for approximately 54.9 ms. Thus, the lowest possible frequency that can be measured is 1/.0549 Hz. Lower range depends only on the sampling time and is practically fixed at 19 Hz (18.2 Hz, to be precise). Upper range depends on factors such as value of the MOD counter used and the operating frequency range of the counter IC. If MOD-N counter is used (where N is an integer), upper limit (UL) of frequency is given by UL=19xN5 Hz. Thus for MOD 16 counters UL@20 MHz, and for MOD 10 counters UL@1.9 MHz. Care should be taken to ensure that this upper limit is within the operating frequency range of counter IC used. Precision of measurement is a machine-dependent parameter. High-speed machines will have better precision compared to others. Basically, precision depends directly upon the number of data read in a standard time. Precision of measurement varies inversely as the value of MOD counter used. Precision is high when MOD 10 counters are used in place of MOD 16 counters, but this will restrict the upper limit of frequency measurement and vice-versa.
Monday, August 11, 2014
10W Audio Amplifier circuit based on TDA1910
Simple and cheap, thats the advantage of this schema. Although the output power is not high but audio quality is good, because TDA1910 has a very low noise feature. This schema suitable for use as a student project.
About TDA1910:
The TDA1910 is a monolithic integrated schema in MULTIWATT® package, intended for use in Hi-Fi audio power applications, as high quality TV sets.
The TDA 1910 meets the DIN 45500 (d = 0.5%) guaranteed output power of 10W when used at 24V/4W. At 24V/8W the output power is 7W min.
TDA1910 Features:
- muting facility
- protection against chip over temperature
- very low noise
- high supply voltage rejection
- low “switch-on” noise.
Download TDA1910 Datasheet for complete TDA1910 reference
