To test the boosted AA flasher concept I used the following methodology:
- Charge capacitor to around 1.5V
- Connect to a 3.3V boost circuit
- Load 3.3V output with a 68k resistor (simulates the 48uA average current draw of concept)
- Measure voltage at periodic intervals
- Calculate average current drawn
I had previously estimated the average current drawn from the AA battery as 140uA when boosting to 3v.
The results I obtained were quite consistent with this until the voltage dropped below 1V. The divergence after 48 minutes is likely to be the fixed assumption for efficiency. As the input voltage drops more current is required and the losses increase.
Still, not bad for a thumb suck.
The planned 4ua sleep versus brief 20mA flash may give a different result due to the boost circuits efficiency varying with load.
It appears this approach will deliver a flashing led with around 3 times the life of the discrete version I built. The next step is to build this prior to Christmas.
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