Showing posts with label LED-Lighting. Show all posts
Showing posts with label LED-Lighting. Show all posts

Tuesday, August 09, 2016

Binary ASK modem - Power line Modem

Want hlp in dsigning of a binary ASK modem or Power Line Modem.

Mail from AM UK

Study these links ....
Amplitude-shift keying (ASK)

Amplitude-shift keying (ASK) is a form of amplitude modulation that represents digital data as variations in the amplitude of a carrier wave. In an ASK system, the binary symbol 1 is represented by transmitting a fixed-amplitude carrier wave and fixed frequency for a bit duration of T seconds. If the signal value is 1 then the carrier signal will be transmitted; otherwise, a signal value of 0 will be transmitted.

OFDM-Based Power Line Communication Modem

"The MAX2990 power line communication (PLC) baseband modem delivers a cost-effective, reliable, half-duplex asynchronous data communication over AC or DC power lines at speeds up to 100kbps. The MAX2990 is a highly integrated system-on-chip (SoC) that combines the physical (PHY) and media access control (MAC) layers using Maxim's 16-bit MAXQ microcontroller core. The MAX2990 utilizes OFDM modulation techniques to enable robust data communication using the same electrical network that supplies power to all other devices on the network."

LEDs Allow New Remote-Controlled Lighting Applications

LEDs Allow New Remote-Controlled Lighting Applications

PLC technology allows communication over a long range. New OFDM-based PLC technology, including emerging standards such as G3-PLC™, is simplifying integration of lighting control applications by providing noise immunity and interoperability.


Tuesday, March 11, 2014

Lighting a LED String - Serial Drive

Hi there, my name is steve. I would like to ask you about the best way or the most efficient way to supply LEDs. there are 36 small LEDs or 72 small LEDs (5mm).

could I just put then in series the 36 LEDs and a diode, resistor and plug in to AC power line (110)

(An email i got some time back)

Answer - Lighting a LED String - Serial Drive

Remember that the LED for lighting or otherwise needs to be protected from over current on Forward Bias and High Voltage connection in Reverse Bias.

That means you could use a 3 A Diode like 1N5408 to prevent wrong polarity connection. Then all you need a constant current source with a voltage output a little above the product of the Number of LEDs and Forward Drop of a LED.

5 LEDs in Series with a forward drop of 3 each means 5 x 3 = 12. You need a 15 Volts Regulated Supply with a current limit of around 30mA or more. See the LED datasheet. Go beyond limits you lose your LEDs the same day or months later.

Use SMPS designs for smaller sizes and it has to be Robust to Mains Power Supply Variations. Use a Surge Protection Assembly from a Reputed and Quality Supplier. (this surge part spoils the reputation of your Lighting Product and affects the entire LED lighting Business)

Read these pages to learn more....

The Perfect LED Light -  by Garry Petrie

"The perfect LED light is designed for cavers who want an efficient, uniform and constant bright light for caving. This article contains some very specific technical information and it is assumed the reader has a basic understanding of electronics. To build the light, the reader also must have some experience soldering, drilling, wiring and cutting small objects."

The Perfect LED Light -  by Garry Petrie

A linear Constant Current LED Lamp Dimmer

"This simple Linear circuit provides continuously variable regulated current (~25-400mA) from a 4-6 Volt source.  I chose a linear design for simplicity, reliability, ease of repair, and to avoid switching EMI in my Cave Radios.  The circuit requires only 0.2V headroom above the parallel LED Array voltage to provide regulation at maximum current. "

A linear Constant Current LED Lamp Dimmer