I want to make an lantern (Candle Light) with one flickering led that i want to power with battery. My goal is to made this as small as possible with good battery time.
I have tried an Attiny85 with one flickering led and total power consumption is 7mA. I can't use an larger resistor on the led because i need as mutch light as i get from that one led.
I have seen cheap lantern in Norwegian stores that costs ariund 1,- dollar (10,- NOK) and the maker og the lantern writes that the led lasts up to 1000 hours. 3v led with C cell battery.
Is there any way i can light up an led (3V) and at the same time use less than 7mA?
How much of your 7mA is being consumed by the led and how much by the attiny? If most is the attiny, there will be ways to reduce that in your sketch. If most is the led, your only option may be to find a more efficient led, if you can.
Have you tried other LEDs to see if they are brighter than your current led? Not all LEDs are created equal. Over the past 20-30 years they have become much more efficient, but old, less efficient designs are still being sold. Look for LEDs claiming high brightness, with clear lenses. But beware LEDs with brightness simply because they have a narrow beam. You need a wide beam for your lantern. Compare the brightness in millicandels (mcd) for LEDs with a similar wide beam. If the LEDs are rated for a total brightness in lumens, that is a better figure to compare, but many do not show that. Words like "high brightness" and "ultra bright" are meaningless. Look for numbers: intensity and beam width.
PaulRB:
How much of your 7mA is being consumed by the led and how much by the attiny? If most is the attiny, there will be ways to reduce that in your sketch. If most is the led, your only option may be to find a more efficient led, if you can.
Have you tried other LEDs to see if they are brighter than your current led? Not all LEDs are created equal. Over the past 20-30 years they have become much more efficient, but old, less efficient designs are still being sold. Look for LEDs claiming high brightness, with clear lenses. But beware LEDs with brightness simply because they have a narrow beam. You need a wide beam for your lantern. Compare the brightness in millicandels (mcd) for LEDs with a similar wide beam. If the LEDs are rated for a total brightness in lumens, that is a better figure to compare, but many do not show that. Words like "high brightness" and "ultra bright" are meaningless. Look for numbers: intensity and beam width.
My Attiny85 consumes around 3mA, and my led consumes 4-5mA.
I have tried varies of leds and i think i have found leds that are good. I'm going to use warm white led, because orange led does not light up enough.
You can reduce the current consuming of the ATTiny near zero* (running from the internal WDT 128kHz oscillator). You cannot do anything with the LED other than using a more efficient one. If you have tried several different LEDs it is unlikely you will find a miraculous one.
Bjerknez:
I have seen cheap lantern in Norwegian stores that costs ariund 1,- dollar (10,- NOK) and the maker og the lantern writes that the led lasts up to 1000 hours. 3v led with C cell battery.
Is there any way i can light up an led (3V) and at the same time use less than 7mA?
Google LM3909
This will possibly be the chip they are using, if not then a derivative of it.
Tom..
How can a capacitor increase the voltage from 1.5V?
Switching, if you read the data sheet or ask google how does a LM3909 work
you may get an explanation.
It will make the LED blink, but not flicker.
Google flickering candle LED
Tom...
Google is your friend...
I know. I have search google alot, but never seen LM3909. I have also search flickering led, but i only see people that use Arduino, 555-timer, Attiny etc.
General purpose ICs running from single alkaline cell (coin, AA(A), C, D) are rare. They are common for single purpose ICs like in watch, clock or such LED toys so it is possible to make such low voltage circuits, and with micropower consumption. Yet they are (nearly) unavailable as a general purpose MCU. Don't know why.
So it is possible to make a low power circuit but not over powered by a single alkaline cell.
