I've spent the better part of this morning looking for the Panasonic transistor mentioned in the title for this project, and I found that it was discontinued in 2005. Unfortunately, I've already orded all the other parts. Does anyone know where I can this part or a suitable replacement?
''The MN1380 series are elements that monitor the power
supply voltage supplied to microcomputers and other LSI
systems and issue reset signals for initializing the system
after the power is first applied or for preventing runaway
operation when the supply voltage fluctuates.''
And so depending on the application needed it’s possible to replace it with other circuits, some examples: LTC1440/LTC1442, or LMP7300
In the schematics, MN13811 compare the supply voltage to an internal reference. The output low level signal will trigger the flash circuit.
There are some solutions to replace the circuit, see for example a possible replacement using LTC1440 or even some bipolar transistors...
As you can see, for a single NiMH cell **broken link removed**
The charging voltage is in the range of 1.4-1.6 V/cell. A fully charged cell measures 1.35-1.4 V (unloaded), and supplies a nominal average 1.2 V/cell during discharge, down to about 1.0-1.1 V/cell (further discharge may cause permanent damage).
For a 2V cutoff voltage yes, this is the right value. Anyway in my opinion a 2.1-2.2V it’s more suitable in the case you want to have enough power in the batteries to make this circuit work. So maybe a 3.9M resistor for Ra will do the trick…