Hello good day to you all - ive been thinking about building a 7 year joule thief but i wanted to do some modifications
in order for it to work better for what im attempting - attatched are links to sites for you to better explaining what im trying to do
- i was thinking of adding a 1 watt or 3 watt led and also a photocell to turn it off in the day - i would like to know what i need to change to add these components to the circuit please

 

You are not going get significant light out of a 1W or 3W LED for seven years from an AA battery.

A joule thief will dimly light an LED from a battery that is nearly dead. It is a curiosity.

Bob

 

A couple of things here: The amount of light you get is largely a function of the current, and is for the most part independent of die size, so you will get about the same light out with a 5mm LED or a 3W LED mounted on a metal core board.

The circuit shown with the particular components used in the demonstration only draw 45 microwatts from a fresh battery, so as BobTPH indicated, you are not going to be able to get much light. Reduce the 2 Meg resistor and you can increase light at the expense of battery life.

You could use a phototransistor to short the output side of the 2 meg resistor to ground during daylight hours. The rising sun may cause the phototransistor to turn off so slowly that the circuit will not oscillate, in which case one solution is to use several cmos Schmitt triggers in series between the phototransistor and the LED circuit, but watch out, you might end up eating more than 45 microwatts in the control circuitry that is supposed to extend battery life.

 

In 2 years that battery will be a dead corroded mess

 

Consider an LM3909 IC. They are obsolete but available on eBay.