I have this cell phone we dont use anymore, but I want to keep it because it has the picture of a love one as wallpaper on the little screen. So I wanted to do this: use a photo- resistor as a light-dark sensor and with some other components, have the phone screen turn on at dark so that the picture will glow in the dark and then put a picture frame or something on my night table. Now, the issue was this: the phone does not have the battery or the power cord (and I dont want to get them). So what I thought in doing was to power the phone with a LM317 and set it to
4.5 V which is what the old battery used to give. First I tried using regular 1.5 V batteries (3 of them = 4.5V) to see how it works, and it works fine; but when I use the LM317 the phone does not turn on at all. As soon as the circuit turns the phone on, the voltage drops to about 1.9V (at the LM317 output), but why?????
Can some one tell me whats wrong? What am I missing? Is it something about the current that needs to go to the phone?
(the phone draws about 200 to 400 mA, the transformer gives about 7.5V output; power on the LM317 would be ~ 1.2W).
Thanks.
4.5 V which is what the old battery used to give. First I tried using regular 1.5 V batteries (3 of them = 4.5V) to see how it works, and it works fine; but when I use the LM317 the phone does not turn on at all. As soon as the circuit turns the phone on, the voltage drops to about 1.9V (at the LM317 output), but why?????
Can some one tell me whats wrong? What am I missing? Is it something about the current that needs to go to the phone?
(the phone draws about 200 to 400 mA, the transformer gives about 7.5V output; power on the LM317 would be ~ 1.2W).
Thanks.
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