bogdan

what i want is to use a receiver and emitter..... i can't find those transcievers around here.

my mainboard has a IR/CIR connector on it, so i want to connect an emitter receiver to it. the pinout on the connector is: for IR: VCC5 key IR-RX GND IRTX VCC and for the CIR: VCC5 stand by x CIR-RX GND x x i assume that x means not connected. if anybody can help, i need to make an IR interface for my cell-phone.

well, keep looking for that schematic.... i really want to try it... also, you know anything about generating power from a pletier moddule by heating it with a candle?

Hearse, the first circuit is missing the current limiting resistor for the led. the second has a bit of a problem... for the second, i would increase the 220 ohm resistors...maybe to 560 .... i find the LM3909 unsiutable and expensive for this application. it is good for places where you want to power a led from 1.5V(a single battery) for this application a 555 is best, or probably a 556 if you want them to flash with 2 different rates. you could also add some transistors and make put together more red leds and more green leds.

Siddhu, this is what i have seen on tv some time ago, yet i didn't catch too much. do you know any website?

when a quartz cristal is swueezed it produces some electricity. has anyone thought to use this for charging something? or maybe use this electricity to power something? these kind of things are used in lighters and other stuff. has anyone actually built this???

the schematic with only the zenner and without the transistor can not suply you too much current. a 1.3W zenner cand suply a few miliamps(sorry, no time to do the numbers). if you want 5V, you might consider using a 5.1V zenner in place of the 4.7V one.

since you are using 4 diodes, this forms a full bridge rectifier. so you need to power your circuit from 0 and 12V. you could use 0 as ground and use 2 diodes, one from each 12V connection and you get a full wave rectifier also. here is what i mean... the 2 circuits show the 2 ways you cand do the rectifying. from the cap you connect the regulator and other components.

well, i have seen something like this. you produce an ultrasound and modulate it in such a way that the human ear will hear as the sounds were at the correct frequency. since you can make the ultrasound unidirectional, i think that this is the sollution. still, making the sound perfectly directional is not possible since it is transmitted trough the air, so the nearby air vibrates along with the sound column and so the sound is transmitted in various directions, with lower intensity of course.

well, i meant to say that the circuit should work for 2 to 5V, and produce enough voltage for the led to light up in the same way, no matter the input voltage. so any suggestions?

well, do you know any common driver, because here components are quite hard to find, so i need something common. maybe some other suggestions?

i found this simple PWM for motor control. it is something usefull, and i was thinking to build it and wanted to know what others think. maybe some of you know a similar circuit, i mean, simple, but maybe more performant? here is the circuit: http://www.geocities.com/tjacodesign/motor/motor.html

anyone cand suggest a led driver chip? one that requires few external components? it should be able to drive 1-2 white leds from a suply voltage like 2-5V....any ideas?

one thing i have thought of would be to use a super cap and some rechargable batteries, and a led driver. this way you could charge the cap, adn also the batteries. the batteries will last longer than the cap. you oculd also add a solar cell to charge it from light. an interesting idea would be to create a rechargable flashlight that can get energy from various forms...like shaking, light, heat(?! maybe it would be possible?) and some other stuff.....so it would be some sort of universal powert flashlight.... i have thought of this, but i don't have the time now to try and experiment some ideas. one way would be to make something really small and light to be very portable....

now, you are now allowed to use a regulator chip.... but what about using a switching chip, with some extra components????? or building a switching with descrete components? if you can use a simple circuit with a zenner and a transistor. mixos, if you look at the second circuit you have posted at a connection called 'sense' you will see that all the resistors connected at the bottom right of the schematic are actually shorted....so.....why are they there?