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| Sources for 3 Vdc |
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| fixit7:
I have a laser beam alarm circuit. The detector and piezo speaker uses less than 100 ma. It will be going outside on my porch. It currently runs from 2 aa batteries. I could run a line from outside to supply the voltage but would prefer a battery source. What are my options for the battery source. I would them to last around a year. I already have some 18650s. I would put the detector and laser in some kind of waterproof enclosure. Thanks. |
| sokoloff:
The very first thing I'd do is try them with two D-cell alkaline batteries... |
| DDunfield:
How much less than 100ma? What is the actual idle (or better yet average) current draw of the device? 100ma is a LOT of current to draw from a battery over a year. Very basic calculation with no account for internal leakage, fall-off, self-discharage etc: Year = 365.25 x 24 hours = 8766 hours 8766 x 100ma = 876600 mah (milliamp hours) A good alkaline D cell might have 15000 mah. Which means it would run a device drawing 100ma for about 150 hours, or just over 6 days. Dave |
| fixit7:
I want to make sure I don't ruin my circuit. To find the exact current, do I measure it by putting my meter in between the positive lead and the switch? |
| garethw:
Put the multimeter in a position so that all of the current passes through it. Right at the battery or in-line with V+ or V-. |
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