Showing posts with label LEDs. Show all posts
Showing posts with label LEDs. Show all posts
WEARIFY

Mobile phone Circuits to Get Even smaller

Transceivers, appliances such as mobile phones that can send and receive messages, have become smaller and smaller over the last few years, but users are about to experience a new meaning in miniaturisation.

Research at The Hong Kong University of Science & Technology (HKUST) has successfully combined a unique system architecture and new circuit design techniques to reduce them in size like never before.
Principal Investigator Dr Howard Luong said the handset of a typical mobile phone today may contain between 150 and 300 separate electrical components.

His research group proposed and demonstrated circuit techniques that make it possible to combine many of these components to a single chip and therefore to significantly reduce the size of circuitry (see example in graphic). A US patent has been granted for one of the circuit techniques.

The transformation applies to the CMOS (Complimentary Metal-Oxide Semiconductor) manufacturing process, which can produce integrated circuits and systems with the highest integration level at the lowest cost. Applying new techniques to the CMOS process, Dr Luong’s research enables many “off-chip” components to be combined to realize a system-on-chip. “But,” he said, “this integration created great challenges in circuit implementation.” Part of the research was to solve the problems by new circuit design techniques.

“The system architecture and circuitry go hand in hand, he added. “They must both work, or neither will be useful.”
The resulting design gives the highest component integration in the smallest chip area ever reported, said Dr Luong.
In his design, all off-chip components are fitted into a central chip measuring 36 mm with packaging, and 8mm without being packaged.
Dr Luong’s miniaturisation method means appliances will soon be made for even lower cost and lower power consumption in addition to being much smaller in size and lighter in weight.
“With the lowering of cost, size and power, many new and interesting applications will become possible and practical,” he said.
Low-power wireless transceivers, for example, could be integrated into implanted devices such as heart pacemakers to wirelessly transmit and receive information between patients and doctors or monitoring systems.
Wearable mobile phones as small as wrist watches at an affordable price could also become a reality.
Read More
WEARIFY

MT8870 DTMF Telephone Dial Tone Decoder Circuit Diagram

Build a MT8870 DTMF Telephone Dial Tone Decoder Circuit Diagram. This is a  simple MT8870 DTMF Telephone Dial Tone Decoder Circuit Diagram. In this circuit one common DTMF receiver IC is the Motorola MT8870 that is widely used in electronic communications circuits. The MT8870 isan 18-pin IC. It is used in telephones and a variety of other applications. When a proper output is not obtained in projects using this IC, engineers or technicians need to test this IC separately. 

A quick testing of this IC could save a lot of time in research labs and manufacturing industries of communication instruments. Here’s a small and handy tester circuit for the DTMF IC. It can be assembled on a multipurpose PCB with an 18-pin IC base. One can also test the IC on a simple breadboard. For optimum working of telephone equipment, the DTMF receiver must be designed to recognize a valid tone pair greater than 40 ms in duration and to accept successive digit tone-pairs that are greater than 40 ms apart. 

 MT8870 DTMF Telephone Dial Tone Decoder Circuit Diagram

MT8870 DTMF Telephone Dial Tone Decoder Circuit Diagram

Read More
WEARIFY

Petrol/Diesel Level Sensor

This sensor is particularly suitable for use in small spaces, such as the petrol tank of a  motorbike. It has the advantage of not having any moving parts, unlike a conventional sensor with a float and float arm that make it difficult to fit in a tank.

The sensor circuit is made from standard, inexpensive components and can be put together for little money.

Petrol/Diesel Level Sensor Circuit diagram:

Petrol/Diesel Level Sensor

The operating principle is  based on  measuring  the forward volt-ages of two identical diodes (check this  first by measuring  them).  The forward voltage of a diode decreases with increasing junction temperature. lf a resistor is placed close to one of the two diodes, it will be heated slightly if it extends above the surface of the  petrol. For best results,the other diode (used for reference) should be located at the same level. lf the diodes are covered by the petrol in the tank, the heating resistor will not have any effect because it will be cooled by the petrol. An opamp compares the voltage across the two diodes, with a slightly smaller current passing through the reference diode.

When the petrol level drops, the output of the opamp goes high and the output transistor switches on. This causes a sense resistor to be connected in parallel with the sensor output. Several sensor circuits can be used together, each with its own switched sense resistor connected in parallel with the output, and the resulting output  signal can be used to drive a meter or the like.

Using this approach, the author built a petrol tank' sensors trip' tank consisting of five PCBs, each fitted with two sensor circuits. With this sensor strip installed at an angle in the tank, a resolution of approximately 1.5 litre per sensor is possible. Many tanks have an electrical fitting near the bottom for connection to a lamp on the instrument panel that indicates the reserve level. The sensor strip can be used in its place. You will have to experiment a bit with the values of the sense resistors, but do not use values lower than around'100 O. It is also important to fit the diodes and heater resistor in a little tube with a small opening at the bottom so that splashing petrol does not cool the heater resistor, since this would result in false readings.

The circuit should be powered from a regulated supply voltage of 5 to 6 V to prevent the heating resistors from becoming too hot. After testing everything to be sure that it works properly, it's a good idea to coat the circuit board with epoxy glue to provide better protection against the petrol.

Tip: you can use the well-known 1M3914 to build a LED display with ten LEDs, which can serve as a level indicator. Several examples of suitable circuits can be found in back issues of Elektor.

Note: this sensor circuit is not suitable for use in conductive liquids.
Read More
WEARIFY

Layman’s RGB LED Module Project

Layman’s RGB LED module is an ultra-simple project realized without any microcontrollers. An RGB LED can be driven with a cmos presettable up/down counter. This is accomplished by connecting the three source outputs (Q1 to Q3) from a CD4029 cmos chip and configuring the device as a presettable counter. The solution presented here is intended to drive red, green, and blue LEDs in a common anode configuration. Color pattern (and intensity balance) is then controlled with the help of an external clock signal generator circuitry.


Layman’s RGB LED Module Project

The CD4029 IC

CD4029 IC consists of a four-stage binary or BCD-decade up/ down counter with provisions for lookahead carry in both counting modes. The inputs consist of a single CLOCK, CARRY-IN (CLOCK ENABLE), BINARY/DECADE, UP/DOWN, PRESET ENABLE, and four individual JAM signals. Q1, Q2, Q3, Q4 and a CARRY OUT signal are provided as outputs. Binary counting is accomplished when the BINARY/DECADE input is high; the counter counts in the decade mode when the BINARY/DECADE input is low. The counter counts up when the UP/DOWN input is high, and down when the UP/DOWN input is low.


Layman’s RGB LED Module Project

The RGB LED

With an RGB (Red-Green-Blue) LED, literally you will be able to produce any color. At first glance, a 5mm RGB LED looks just like the regular 5mm LEDs, however, inside the standard package, there are actually three LEDs; one red, one green and yes, one blue. By controlling the brightness of each of the individual LEDs you can mix pretty much any color you want. A common anode RGB LED is the most popular type, and it is nothing more complicated than three one colour LEDs (one red, one green, and one blue) housed in a single package. However, rather than having 6 leads (cathode and anode for each LEDs) it has only 4 leads; one cathode for each colour (RGB), and the common anode (CA). Usually, the common anode of the LED package is the second pin from the flat side of the LED package. It is also the longest of the four leads. This lead will be treated as the “common” pin of the RGB LED.



Layman’s RGB LED Module Project


The RGB LED Module

As said, the circuit is built around CD 4029 IC and a few other external components. The finished module can be powered from any “clean” 5-Volt dc supply source for driving the RGB LED connected at the output of the circuit. In addition, the module calls for a suitable clock pulse at its input which can be supplied from a suitable clock generator wired around discrete components, or from a microcontroller based circuitry. Needless to say, this inputted clock signal determines the color pattern and intensity balance of the RGB LED’s aesthetic visual output. Refer the following application circuit:


Layman’s RGB LED Module Project


RGB LEDs have differing forward voltages (VF) for the red, green, and blue LEDs. When drived by a 20mA per LED current, the red LED element of the RGB LED used here has a forward voltage of about 2V. The green and blue LEDs have forward voltage levels of about 2.4V and 3.6V respectively. Note that the forward voltage drop for each LED within the RGB LED need to be well-equalized in order to match LED performance over the operating range. These ballast resistors are used in the prototype; RR = 150R , RG = 120R, RB = 68R.



The Clock (CLK) Signal

Since the CARRY-IN (CI/pin 5) and PRE-SET ENABLE (PE/pin1) inputs of IC1 (CD4029BE) are held at low level, the counter is advanced one count at the positive transition of clock signal fed through the clock input (CLK/pin 15). Advancement is inhibited when PRESET ENABLE input (pin1) is pulled to a high-level (here by Q4 output of IC1). Based on this, we can feed a suitable clock signal to the module (through J1) for driving the onboard RGB LED as per our requirement. For testing your finished circuit, just try out an external clock pulse generator centered around the single most useful integrated circuit in history, the 555 timer chip. Refer the following sample application circuit:



Layman’s RGB LED Module Project


Here, when wipers of P1 and P2 are bolted at their mid-travel (ie. 5K value), output from NE555 is about 0.952 Hertz (frequency) @ 67 % (duty cycle). However, adding a 1N4148 diode between pins 7 and 6 of NE555 ( its anode to pin 7 & cathode to pin 6), this will changes to near 1.429 Hertz @ 50 %.

Hooked to CD4029?

Recently we published an “Improved Impulse detector” circuit based on the same chip CD4029. At that time CD4029 was wired as an upward counting decade counter. But now the same CD4029 works as a binary counter whose outputs continuously count in a binary progression between 1 to 7. These outputs drive the 2N3904 transistors (T1, T2 and T3) which, in turn, control each of the three colours of the RGB LED. Now it’s your turn; refer the CD4029 datasheet, and carefully walk through both circuits to find out the typical configuraton tricks used by us!

Sourced By : W3circuits
Read More