A cheap laser pointer shining into an LED can create small voltages, the photovoltaic effect. Wardy uses it to power an ultra low power ATTiny5 microcontroller:
I may have raised an eyebrow slightly to see 2.50V appear on the screen. Hmmmmmm. I had been expecting something like 0.25V or something in that region, based on experiments with LED sensors a few weeks ago.
An idea occurred!
I’ve got an ATTiny5 microcontroller on my bench… can I have it running a USEFUL program while being powered only by the incident light striking a cheap LED?
Oh now that sparks some ideas, and I will surely test the effect tonight… Had an idea of something that needs power several yards from the house, who wants to use batteries when you can use lasers to power your electronics….
Where’s this from? Link?
Sorry, fixed:
http://wardyprojects.blogspot.com/2012/08/using-laser-to-power-attiny5.html
surprised it had enough power as well…thought the ATTiny microcontrollers used more power than the PIC ones…
Hey, thanks for featuring my article guys :D I hope people find it entertaining and useful in their own projects.
Cheers,
Wardy.
I used to run the Xilinx CPLD applications team. We got a lot of mileage out of running XPLA3 CPLDs with grapefruits wired in series. Tiny, tiny currents. When we released CoolRunner-II, we had to outdo ourselves, so we ran one of those off of about three tiny cumquats (citrus about the size of grapes). Our field applications team always looked for fun ways to power low energy circuits and one of the most novel was with multiple glasses of Molsen gold beer. I think the original grapefruit battery was in the ‘Handbook for Boys’ from either the Cub or Boy Scouts. I just wanted to add a little ‘chemistry’ to Wardy’s comments about physics!
That’s brilliant. Also it’s nice to see a hardcore EE company with a sense of humour. Incidentally I’ve just started to learn about FPGAs and I’m using a Papilio One dev kit (with a Xilinx Spartan 3E 500K). Exciting stuff!
This technique (usually with small silicon photovoltaics, but LEDs should work fine) has been used for extreme high voltage isolation such as in a particle accelerator. If your circuit operates floating at the top of a 1 megavolt acceleration potential, ordinary isolation transformers won’t do you any good.
I seem to recall a similar project presented back on April first.
Here in the UK, we celebrate Fool’s Day in August.
The laser thing works though.
Hey,
Thanks for the video. I am looking for something close to this.
I am presently working on a sensor which utilizes laser of 473 nm, 600 nm and 800 nm, which will be switched on, one at a time. The light should go through sample, fall on photodiode which converts this intensity to voltage. Now, I store these voltage values in micro-controller and do the calculations.
I will be using AVR Atmega 16/32 Mc.
How will I interface my diode with micro-controller?
Could you suggest any method?
Sounds like you wouldn’t be powering the ATMega using the laser, but you’d use a normal power source like a battery or mains adaptor as usual. What you’d need to do is hook up the photodiode or LED to one of the ADC channels and then write code that performs the AD conversion on the ATMega. This will return a value in the range 0 to 1023, where 0 maps to 0 volts and 1024 maps to the voltage you’re providing to the ATMega’s “AREF” pin. This AREF voltage will need to be something you can calibrate (probably with a potentiometer).
The sampling process would go something like this…
– Insert sample into the measurement aparatus.
– Take an ADC reading with no light to give you a calibrated 0V value.
– Turn each light on in turn and use the ADC to measure the voltage each time.
– Compensate each of the 3 readings with your 0v reading.
– Then do some maths on the values that is specific to your application.
– Export the values to whatever system needs to know them. Maybe a PC or another device of some kind depending on what you doing.
For my laser and LED setup I would have used an AREF value of 2.5 volts because that was the maximum voltage I could produce by firing the laser into the LED at point blank range with no attenuation.
Hope this helps you :)