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

Wednesday, June 01, 2016

LM3914 meter for 25 V DC

"I wish to assemble a bargraph display to indicate approximately 25volts dc.How many LM3914 I should cascade? How to calculate resistor value which is grounded from the junction of Pin 6 & 7 (Rhi &Ref.out)? Assuming i need to cascade 3 LM3914s,what is the method to cascade these ics? The display need not be precise or very bright. I hope you can help me out."

Mains Voltage monitor using LM3914

"I shall be very grateful. Can we do it in such a way that the first LM3914 displays 1-10 v & second 11-20v & the third 21-30v?"

Thank you again - Mail from AD

Reply from delabs

Have a look at the TI application note which has many examples. Understanding this will help you make your own solution.

LM3914 - Dot/Bar Display Driver

20-Segment Meter with Mode Switch

20-Segment Meter with Mode Switch

Analog and 3-1/2 digital display

Cascading is required if you want more resolution. Example for measuring 20V, you want to show in 1V per LED steps. It can withstand +/- 35 Volts input upper limit.

The inbuilt reference is 1.2V use it as shown in the Typical Application. This also helps in setting the brightness of LED display. You may need to use external attenuators, buffers or precision  rectifiers to measure AC voltages or High Level DC voltages.

Monday, May 02, 2016

Piezo Power Shoes with LEDs

Walking is a Source of Energy that can be Harvested to Power LEDs or Wearables. It may one day Recharge your Smartphone or tablet. Just start running when the Battery goes low on your Phone. -

A question in the G+ Community lead to a study of resources in the web for this college project.

Here is the first page that will interest you - Parasitic Power Shoes Project

Energy Harvesting in Shoes for Small Devices

"environmental energy sources can begin to replace batteries in certain wearable subsystems. In this spirit, this effort has examined devices that can be built into a shoe, (where excess energy is readily harvested) and used for generating electrical power "parasitically" while walking."

Goal: To develop a rugged piezoelectric shoe insert and complementary conditioning electronics for unobtrusive, parasitic harvesting of the compression energy normally lost while walking

See also Energy Scavenging with Shoe-mounted Piezoelectrics

"Abstract of pdf below — Much energy harvesting research has been conducted with ceramic based piezoelectric transducers on account of their relatively large electrical response to mechanical excitation. However, notwithstanding their comparatively low piezoelectric coefficients, piezoelectric polymers too hold promise as energy harvesting materials due to their flexibility and strength which make them ideal candidates for use in more diverse applications. "

Piezoelectric Energy Scavenging In Shoes

"The energy harvester devices are capable of capturing environmental energy and supplanting the battery in a stand-alone module, or working along with the battery to extend substantially its life. Vibration is considered one of the most high power and efficient among other ambient energy sources, such as a solar energy and temperature difference."

Development Of Energy Harvesting Source From Piezoelectric Shoe

Piezoelectric materials (PZT) can be used as mechanisms to transfer ambient vibrations into electrical energy that can be stored and used to power other devices. With the recent surge of micro scale devices, PZT power generation can provide a conventional alternative to traditional power sources used to operate certain types of sensors/actuators, telemetry, and MEMS devices.

Power Walking - STAB Resources

"i started by looking at the self-powered shoe from Responsive Environments group and wanted to acquire a large piece of piezo film that could be embedded in the sole of a shoe. After consulting with Mark Feldmeier, I learned that the piezo elements large enough to generate enough power for the shoe would be too expensive to use if I wanted to make more than just a single prototype."

Piezo-Powered Self-Lighting Circuit

Monday, April 06, 2015

Using LEDs with Battery Power

What are LEDs ? How can we use them for Long Battery Life

Mail from AD

If LED flashes at 5-10 K Hz at even 50% Duty Cycle. It may save some power and improve life. So it is just an idea, it may not solve the problem. The idea was to improve battery life and give uniform light for annunciators. It may not be good for flashlights.

Light-emitting diode - Wiki

Light-emitting diode - Wiki

LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching.

The LED Museum

The LED (and Laser) Museum. A site devoted to testing & reviews of LEDs & LED flashlights in all common chemistries.

LEDs and OLEDs
Small lights with big potential: light emitting diodes & organic light emitting diodes.

Light Sources in Electronics
Light can be produced and/or controlled electronically in a number of ways. In light emitting diodes (LEDs), light is produced by a solid state process called electroluminescence.

Using LEDs with Battery Power


Wednesday, November 19, 2014

Electronic Fifteen LED Roulette

The following was submitted on July 11th, 2007 at 12:47AM (PDT). Message: I want to combine Ne555 with 74154 IC.The indication of the outputs must be shown with LED's but up to so far it need 15 outputs ,is it possible the way i did? if not i will need your assistance

Mail from CY

LED running lights are used to decorate Christmas Trees, Festival Surroundings and even  Buildings. A Clock and a counter are basically required. Many LEDs can be used in parallel with driver transistors. Upto 15 count is is good enough. Many colors can be used and with a PWM or VCO you can make it Audio or Music effects lights like strobe lights.

Electronique RĂ©alisations - Roulette

Multi-Colored LEDs and drivers and even PIC microelectronics with Visual Effects in the form of ROM tables can make Alphabets and Numbers appear in LED arrays. Some have made Mini Ocillosocpes and Toy Spectrum Analyzers too in LED DOT Matrix Arrays.

LED Sequencer Circuit

Electronic LED Roulette

See these circuits you will get an idea, Using CD4514 is also possible.

555 and CD4017 Running Lights