ECE engineering projects LM3915 / LM3914 IC

Soil Moisture level detector using LM3915 IC

Hello Engineers. Sometimes, we need to check the level of moisture or dryness of Soil or even Sometimes washed clothes in winters in order to check the moisture or dryness level. I have discussed, a simple and compact digital soil moisture level detector circuit to check whether the soil is dry or wet. It can also be used to check the dryness or wetness of cotton, woolen, etc. So, let’s discuss further.

I have used IC LM3915 in this circuit which is a monolithic Integrated Circuit that senses the analog signal voltage levels and accordingly drives 10 LEDs Bar or dot Matrix display. To understand ICs in-depth working

In this circuit, the number of LEDs glowing represents the dryness level or Low/(or no moisture in case of D9 or D10 glowing) level of moisture.

If only one LED, D1(connected to PIN 1) is Glowing, that means fully wet or a very higher level of moisture. Initially, when you turn the circuit is turned ON, all the LEDs are glowing which shows the max dryness level.

The higher number of LEDs glowing shows the level of dryness. The lower the number of LED glowing means higher the moisture and lower dryness.

Materials and Components

  • LM3915
  • R1 4K7
  • R3 2.2K
  • R2 12K
  • R4 1.2K (1K2)
  • D1-D12- LED Red
  • D11 – 3.3V Zener
  • VR1 – Pot 10K
  • C1 – 100uf
  • B1 9v-12V
  • Switch
  • Metallic Probes

Soil Moisture level Detector Circuit

soil moisture level detector display

The circuit is very simple and useful. You can check the moisture/ dryness level that can be displayed by the LEDs display.

The circuit can be powered by 9V to 12V supply input at Pin 3 (Vcc). When the circuit is turned ON, usually all the LEDs are turned on, showing the ultimate dryness level or no moisture at all.

The circuit’s Probes can be of alluminium or copper. Multimeter Probes head are also good.

If there is some moisture the number of LEDs glowing will eventually fall according to the increase in wetness (or fall in dryness level)of soil/ cloth.

More number of LEDs, means more amount of dryness. To understand the IC LM3915 working in detail, you can visit here.

If you guys liked it, or have any questions please do comment here. Thank You. Keep supporting.

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Aabhishek Sharma is a Computer Science Engineer and a Digital Marketing Trainer and Consultant. Aabhishek Sharma also loves working on Electronics Projects and working with microcontrollers and Designing Home automation Gadgets.

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