Battery Level Indicator Circuit with C945 / C828 Transistor – No IC Needed [Sekhohub.online]
✅ Introduction
This project shows how to build a battery level indicator circuit using only C945 or C828 NPN transistors, LEDs, and resistors—no IC or microcontroller required.
It’s a simple and cost-effective way to visually monitor battery voltage levels, perfect for beginners and DIY electronics hobbyists.
Materials for the Project
1- 5x LEDs
2- 5x DIODES (1N4007 OR 1N4148 )
3-5X TRANSISTORS (C945 OR C828
4- 1X 11V ZENER DIODE
5- 5X 10K RESISTORS
6- 5X 1k RESISTORS
7- 1x PIECE of VERO BOARD
8- SOME JUMPER WIRES
Download Circuit Diagram
C828 Transistor Pinout (Almost identical to C945)
| Pin Number | Name | Description |
|---|---|---|
| 1 | Emitter | Connect to Ground |
| 2 | Collector | Output to load (LED side) |
| 3 | Base | Input control via resistor |
⚙️ Working Principle
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The base of each transistor is connected through a voltage divider.
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Each transistor switches ON at a different battery voltage level.
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When the base voltage exceeds ~0.7V (Vbe), the transistor conducts, and the corresponding LED turns ON.
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This way, you can see how many LEDs are ON, giving a rough idea of battery level.
Advantages
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No IC, no programming
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Works with commonly available C945/C828 NPN transistors
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Expandable for more voltage levels
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Good for 6V, 9V, or 12V batteries