lazerlover
Newly Enlightened
- Joined
- Jul 6, 2007
- Messages
- 35
Was wondering if any of you guys knew of a compact LED that could be powered by 0.5V, and 600mA.
Many Thanks
Many Thanks
I received some 1000-1500 MCD 5mm Red LED Emitters from DX yesterday and they would not light up with a 1.5V button cell.so if you want a low voltage LED you might be able to find LEDs that glow red for somwehere between 1.2V-1.6V
I received some 1000-1500 MCD 5mm Red LED Emitters from DX yesterday and they would not light up with a 1.5V button cell.
I had to use a 3V CR2016 to get them to light up, so those ones won't meet the original posters needs (if he wanted red LEDs).
Silicon transistor-based Joule Thief will work down to 0.5v, but only barely. Germanium transistor usage will take that down to 0.25v pretty easily.Was wondering if any of you guys knew of a compact LED that could be powered by 0.5V, and 600mA. Many Thanks
The forward voltage of a red LED is around 1.7 - 1.8 volts, so of course it will not light on 1.5 volts.
If you have a ten foot wall and you have a pole vaulter that can pole vault nine foot walls, he will not be able to pole vault over the ten foot wall. It's not like he will be able to pole vault over the wall only nine-tenths of the time, or maybe only nine-tenths of him goes over the wall. No, he smacks into the wall every single time, and doesn't get across.
Toshi
Yes, but the forward voltage of an LED is not exactly a 'wall' with a specific height which you either clear or don't. At least not one that's specified in the data sheet or discussed in the community.
As you reduce the current in an LED well below the rated current, the voltage drops well below the rated voltage. It definitely doesn't head toward zero, or even closer to zero than to the rated voltage. I have seen in an array of white LEDs operating at very low current that some are emitting and others are not. It has to be pretty dark to tell the difference. This definitely suggests a 'wall' you need to clear to get light, but its height varies between supposedly identical LEDs, and is much lower than the rated voltage of the LEDs. Also, the light intensity at this operating point is normally so low that it's not even useful.
So with a ten foot (LED) wall and a nine foot vaulter, you actually ARE likely to score some points, though you aren't going to win a medal.