With this dry running protection system, you can prevent your water cooler’s motor from dry running and activate it for about one-third of the time only. This will reduce the wear and tear of the motor and save electricity too. Coolers are used in many homes, offices, schools, and industries, especially in summer.
So this device will come in handy to stop the cooler pump automatically when the cooler’s tank has no water.
DIY Dry Running Protection System for Pump is shown in Fig. 1 and its circuit diagram is shown in Fig. 2.
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| Components Required for Building Dry Running Protection System | |
| Semiconductors: | |
| IC1 | -LM7805, 5V voltage regulator |
| IC2 | -NE555 timer |
| IC3 | -4017 decade counter |
| BR1 | -1A bridge rectifier |
| LED1, LED2 | -5mm LED |
| D1 | –1N4007 rectifier diode |
| D2-D5 | -1N4148 signal diode |
| T1 | -2N2219 NPN transistor |
| Resistors (all 1/4-watt, ±5% carbon): | |
| R1, R6 | -1-kilo-ohm |
| R2 | -470-kilo-ohm |
| R3 | -47-kilo-ohm |
| R4 | -10-kilo-ohm |
| R5 | -680-ohm |
| Capacitors: | |
| C1 | -1000μF, 35V electrolytic |
| C2 | -100μF, 16V electrolytic |
| C3 | -10nF ceramic disk |
| Miscellaneous: | |
| CON1-CON4 | -2-pin connector |
| S1 | -Water sensor probes made of steel (2) |
| RL1 | -5V, 1C/O relay |
| X1 | -230V AC primary to 9V, 500mA secondary transformer |
| -Cooler pump | |
DIY Dry Running Protection System – Circuit Diagram
The circuit comprises step-down transformer X1, bridge rectifier BR1, 5V voltage regulator LM7805 (IC1), decade counter 4017 (IC2), rectifier diode 1N4007 (D1), signal diode 1N4148 (D2-D5), NPN transistor 2N2219 (T1), 5V single changeover relay, and a few other components.
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