Wireless Water Level Indicator Without MCU

By Pranav Rameshji Rokde


A wired water-level indicator uses many wires, whose resistance increases as their length increases. A wireless water level indicator using microcontroller (MCU) is costly and not very easy to program. Presented here is a low-cost wireless water level indicator without an MCU.

This circuit has transmitter and receiver units. The transmitter unit is placed near the water tank, whereas the receiver unit is placed inside the house for monitoring four different levels: low, middle, full and overflow.

Wireless water level indicator circuit

Circuit diagram of the transmitter unit is shown in Fig. 1. It consists of 433MHz RFtransmitter module TX1, an encoder HT12E (IC2), a 5V regulator 7805 (IC1), DIP switch DIP1, npn transistors BC547 (T1-T4), connector CON2 for connecting the sensors in the overhead tank and a few other components.

wireless water level indicator circuit: transmitter unit
Fig. 1: Circuit diagram of transmitter unit of the wireless water-level indicator
wireless water level indicator circuit: receiver unit
Fig. 2: Circuit diagram of receiver unit of the wireless water-level indicator

Bases of T1 through T4 are connected with resistors R7 through test points72R10. Each water-level sensor is connected to the circuit through R7 through R10. Water levels are marked as low (L), middle (M), full (F) and overflow (O) in the circuit. The common terminal is marked as C on CON2.


When parts list72water level increases, the transistors conduct and the output signal at their collector changes. Output of each transistor is fed to IC2. Encoded data from IC2 is transmitted through TX1.

Circuit diagram of the receiver unit is shown in Fig. 2. It consists of 433MHz RF receiver module RX1, a decoder HT12D (IC4), 5V regulator 7805 (IC3), DIP2 switch, LEDs (LED4 through LED7) and a few other components.

Data is received by RX1 and decoded by IC4. Different water levels are indicated by the glowing of LED4 through LED7. Resistors R14 through R17 are pullups connected to IC4.

General-purpose 9V batteries are used to power both the circuits. LED1 and LED2 are power indicators and LED3 is used to indicate a valid transmission status.

Construction and testing

An actual-size, single-side PCB for the transmitter unit is shown in Fig. 3 and its component layout in Fig. 4. An actual-size, single-side PCB for the receiver unit is shown in Fig. 5 and its component layout in Fig. 6. After assembling the circuits on their PCBs, enclose these in separate plastic boxes.

Fig. 3: Actual-size PCB pattern of the transmitter unit
Fig. 4: Component layout of the PCB shown in Fig. 3
Fig. 5: Actual-size PCB pattern of the receiver unit

You can use 9V regulated power supplies instead of batteries to power the circuits. For troubleshooting, check voltages at various points mentioned in the test point table.

Fig. 6: Component layout of the PCB shown in Fig. 5
Fig. 7: Sensors in the overhead tank

Make a separate PCB for the LED indication (shown by the dotted lines on the right side of Fig. 6). Use different LED colours for different levels.

Use a waterproof box for the transmitter unit to protect it from rain water.

When both the circuits are switched on and LED3 glows, it indicates that the transmitter unit and the receiver unit are connected successfully. If the addresses of the units are different, LED3 will not glow.

Use DIP switches (DIP1 and DIP2) to set the addresses. Switch on pins 1, 2 and 7 of both the DIP switches to make a secure connection.

Fig. 8: Author’s prototype of the transmitter unit

This will prevent interference from nearby RF transmitters. Connect the sensors in the tank as shown in fig .7.

Fig. 9: Author’s prototype of the receiver unit with LED display

Author’s prototypes of the transmitter and receiver units are shown in Figs 8 and 9, respectively.

Download PCB and Component Layout PDFs: click here

Pranav Rameshji Rokde is a Electronics enthusiast from Nagpur, Maharashtra



  1. pl suggest / recommend a low cost water level sensor. the metallic contact type arrangement fails. what is the life of normal 9V battery in the above circuit

    • Hello sir,
      You can use float sensor which is easily available in near by electronics market.
      Normal 9V battery life is near about one to two week but you can use rechargeable batteries .

    • hello sir,
      you can soldered at metallic contact which can increased that contact life or you can use float sensors which easily available near by electronics market at low cost.you can also refer datasheet of float sensors.

  2. You not mention anything about sender send all the time and battery will soon be die !
    – and I missing info why HT12E encoder osc. is 1 mohm while HT12D decoder osc. is 47Kohm !? – don’t they need to be same ?

    Regards Erik

    • Hellow sir, While designing and testing these values are sutiable…and you can also use rechargable batteries insted of regular batteries

    • Hellow sir, While designing and testing these values are sutiable…and you can also use rechargable batteries insted of regular batteries

    • You can change the dip switch sequence for each instillation so different sequence for all. Both the sequence need to match up at receiver and transmitter side.

    • Hello sir, yes RF interference occurred but by changeing dip switch code your wireless water level indicator dose not interference with your neighbors…..

  3. i triple checked my circuit and replace decoder ic twice.At my receiver unit all led are glow continuously,either transmitter unit is ON or OFF transmission LED always HIGH, and i checked the test points and all voltages are as mentioned…..plz…plz help me…..thanks in advance for your help..

    • Sir, kindly check your transmitter section, there may be linked problem or also their may be problem with your RF Modules..

    • Yes you can directly connect sensors to CON2. Stainless steel rods for use as water level sensors are available in the market.

    • The range depends on the type of RF modules and the antenna used. You can easily get RF modules ranging from 30 meters to 90 meters.

  4. Please go through the text again especially Circuit and working section. Make sure that the address lines A0-A7 of HT12E and HT12D should be same.

  5. friend i need to make the project
    i need full component of the project can you sent the component to the UAE with full drawing and should be pirnted circuit board with mension

  6. on what software the wireless water level control will compile
    please sir help me it was given as final project
    thank you.

    • Yes, but without DIP switch you won’t change address line according to you and it is difficult to connect wires in this PCB layout in place of DIP switch. If you leave all the address line pin floating then it is chance for decoder IC may receive garbage value.

  7. Hi EFY,
    The great things are always beautiful ,such as the diy projects of EFY.
    here I am thanking you in advance for the better job.
    can I add a relay circuit with this to control the single phase 1hp motor?
    if so please sent me the circuit with description through my email.

  8. hi every one,
    i am an engineering final year student, as apart my final project i am looking for a water level sensing element which must have wireless technique. i had the complete signal conditioning and processing circuit, but i need a sensor to detect water level(NON CONTACT TO WATER). Actually, i tried a lot around the internet but i didn’t succeed. could any one help me.

  9. Hello EFY, your project are too good….i want to add in this wireless water level indicator for overflow led replace by buzzer. So,can i connect buzzer in place of led 4. I tried to register on your website but the password is not coming on my mail. Please help me about this….

  10. hi,
    i want to know complete details about TX1(433 MHz transmitter module) and RX1(433MHz receiver Module) datasheets and where i can purchase these two


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