| T O P I C R E V I E W |
| jules |
Posted - May 16 2007 : 4:23:34 PM
Hi, I have made a simple solar cell charger to charge a 12V sealed lead acid 7Ah battery. The battery is used to drive a 12V cooling fan. In low light levels, the fan is still on and discharges the battery below a safe 11.8V. I need a simple switch to disconnect the load when the battery is too low, but to auto-connect when the battery has charged back to a safe level (13,8V), so some hysteresis is needed. I think a power MOSFET would control the power to the fan, and this would be switched by an opamp? Am I on the right track? If so, has anyone got a link to a simple schematic? Thanks. |
| 1 L A T E S T R E P L I E S (Newest First) |
| Aaron Cake |
Posted - May 17 2007 : 09:30:07 AM
You basically hit the nail right on the head. A simple comparator circuit based around a low power op-amp with a transistor/MOSFET/whatever to switch the fan is the solution. If you Google "comparator" you should find some examples. |
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