Circuit Diagram
How to Build It
- Place two LM358 op-amps (or one dual LM358, using both comparators) on the breadboard.
- Build a resistor voltage divider connected to the battery under test, with different thresholds tapped from different points.
- Connect each threshold to a comparator's non-inverting input.
- Connect a fixed reference voltage (from another point on the divider) to each comparator's inverting input.
- Connect each comparator's output to an LED, with a limiting resistor.
- Test with a fully charged battery, then a partially drained one — the number of lit LEDs should decrease.
Bill of Materials
| Product | Code | Qty |
|---|---|---|
| Integrated circuit | — | 1 |
| Integrated circuit | #N/A | 1 |
| LED component | LTL1CHTBK4 | 1 |
| LED (3/5/10mm, SMD, power) | l-934ID-12V | 1 |
| Resistor | DR47K-8/9 | 3 |