1 Watt LEDs are widely used in Emergency lights and LED lights. Most of the circuits use 4 volt battery having 0.5 to 4 Ah capacity. The 1 watt LED is rated 3.6 volts maximum so we need the correct value resistor for LED to get maximum brightness. Let us see how the LED resistor value is determined.
Continue reading “How to select resistor for 1 watt LED”
Solar Garden Light
Make a lighting path in the garden using this simple Solar LED light. It automatically turns on in the evening and gives light in the garden. LED light turns off in the morning. You can select any colour LED like Green, White or Yellow as per the choice.
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One Damaged Mosquito Swatter was in my home with full of dust. So, decided to salvage its parts to reuse for other purposes. Just to avoid e –waste and to do some kind of Recycling. Well, it has a good 2.4V Rechargeable Battery and a circuit board. The problem is in its circuit board that generates high volt AC to burn the Mosquito. But the charger is still working. So decided to use the charger part to make a High power Rechargeable LED Flash light. The Mosquito Swatter generates a high voltage between 400- 1000 volts from the 2.4 V battery. For this, there is an oscillator circuit and an Inverter transformer. The Inverter transformer converts the 2.4 V DC from the battery to around 200V AC. The oscillator circuit makes the AC waveform. The 200 V AC thus produced is then boosted by a Voltage Multiplier comprising some high volt capacitors and diodes. This boosted AC appears in a High volt Capacitor which then passes it to the Nets of the Swatter. The middle net of the Swatter is Positive while the outside nets are Negative. When we press the switch, the High volt capacitor discharges high volt AC to the nets. When the Mosquito passes through the net, it explodes due to high voltage. Even though the AC voltage is very high around 1KV, Current is negligible. Let us see how that Swatter turned into a Rechargeable Flash light.
Continue reading “Hacking Mosquito Swatter. Start Up Project 28”
Probably, this may be the smallest 1 Watt LED Torch working on a Watch battery. It is the “Micro Joule Thief circuit” that is made as compact as possible. It rests on a heat sink of the 1 watt LED and powered by a 1.5V Button Cell. We can make different types of Joule Thief circuits and this experimentation is to make it as small as possible. Try it.
Continue reading “Button Torch. Start Up Project 12”
Harvest energy from the USB port of your Laptop or PC to light an LED lamp. It is useful as an Emergency lamp in the event of a power failure or it can help you to use the Key pad in night without disturbing the sleep of others. It is too simple and easy to make it. The USB.2 .0 port available in all laptops and PC gives 5 Volt DC and 200-300 milli ampere current. It is enough to light a High power 1 watt LED. Just plug the light in the USB port and enjoy its light. Cool! it is good enough to read a book also. In the market its costs Rs. 300 and you can make it for just Rs.10.
Continue reading “USB Light. Home Utility Circuit 30”
Ohms law is a must in circuit design to calculate, Current, Resistance and Voltage in the different sections of a circuit. Ohms law simply represents the relationship between voltage, current and resistance. Let us see how Ohms law is applied to select the current limiting resistor for LED.
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High current White LED requires constant current for giving maximum brightness. Connecting 1 Watt LED to the DC source using a current limiting resistor gives poor performance and the LED will be either too bright or too dim. More over, the low value resistor (10 Ohm or less) will heat up since the LED consumes around 200 to 350 milli ampere current . So here is a simple LED driver chip AMC 7135 that gives constant current (CC) to LED to give maximum brightness. It also increases the life of LED. It is too simple and enjoy the project.
Continue reading “LED Driver CC Chip .Design Note 40”