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- The example resistors in the adjustable section are R1 always 3K
- and R2, varies. You can double R1 and double R2 and get the
- same output voltage.
- So I will use an R1 of 6.8K
- with a base resistor, and an adjustable of
- base
- (would be for 13.5-13.8 according to powerstream sla page) volts)
- so let's do the math
- for 13.65 float voltage.
- 6k( /(13.65/1.23) - 1 )
-
-
- 13.65 / 1.23 - 1 == 10.09756
-
- 6k / 10.09756 == 594.31
-
- There is a 590 resistor in e24 or something. Let's do that.
-
- That is base.
-
- For lowest voltage of 1.2volts (single nicad charged by sun)
- though nicads probably have memory issues, but they are cheap
- so who cares... (I think nimh might be better?)
-
- 1.2 = 1.23( 6k/??? + 1)
-
- So solve for R2 which is unknown
-
- However my earlier math is wrong, since I need a 5900 resistor
-
-
-
-
- 13.65 / 1.23 - 1 == 10.09756
-
- 5900 / 10.09756 == 584.29
-
- So still a 590 resistor... Close as we can get. Well,
- there is a 583 on my chart, so
-
- 5900
- 583
-
-
- Base is 583, 5900 is R1
-
- Now what is the adjustable.
-
- Solve for R2, and remember you need the difference
- And can't go below reference...
- R2 == 5900 / (1.3/1.23 - 1)
- 1.3/1.23 - 1 == 0.0569
- 5900 / 0.0569 == 103690
-
- Quite a difference. We need to jump from 100K to 583.
- So I would add a 100K and that should get me close to 1.4 volts.
- Hopefully close enough. Done.
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