Schematic of the Water Valve Controller Circuit

Presented here is a simple electronic circuit which can control the valve operation by sensing valid-movements with the help of a Passive Infrared (PIR) motion sensing module. In practice, automatic taps are presence sensors and not motion sensors. They employ “Active Infrared” technology which senses “presence” and not “movement” of objects. However, here an unorthodox “Passive Infrared” technology is used to realize the 6VDC powered smart faucet controller circuit!

Schematic of the Water Valve Controller Circuit

555 datasheet

Smart Valve Controller is a combination of four key components:

• motion sensor with control electronics
• solenoid valve
• power source
• and the faucet

As stated, at the heart of the circuit is a Passive Infrared (PIR) module. PIR sensor is a pyroelectric device that detects motion by measuring changes in the infrared levels emitted by surrounding objects. Pyroelectric devices, such as the PIR sensor, have elements made of a crystalline material that generates an electric charge when exposed to infrared radiation. The changes in the amount of infrared striking the element change the voltages generated, which are measured by an onboard amplifier.

The device contains a special filter called a Fresnel lens, which focuses the infrared signals onto the element. The PIR Sensor requires a ‘warmup’ time in order to function properly. This is due to the settling time involved in ‘learning’ its environment. this could be anywhere from 10 to 60 seconds. During this time there should be as little motion as possible in the sensors field of view. There is a variable resistor (P1) on the PIR sensor module to control the ‘ON’ delay time for the sensor. Turning this variable resistor clockwise will give longer ‘ON’ delay time while turning anticlockwise will reduce the ‘ON’ delay time. The PIR sensor has distance range of approximately 3 to 7 meters. It is possible to adjust distance of detection with the help of the second variable resistor (P2) on the PIR sensor module.

Likewise, there is a 2-position jumper point (JP) is included in the PIR sensor module. The sensor is active HIGH (LOW in idle state) when jumper is in either position. In “retrigger” (H) position, output remains HIGH when sensor is triggered repeatedly. In “normal” (L) position, output goes HIGH then LOW when triggered. Continuous motion results in repeated HIGH/LOW pulses.

The motion sensor with control electronics circuitry is very simple and self-explanatory. Output of the PIR sensor module (SEN1) is here connected to a ‘traditional’ monostable multivibrator (MMV) wired around the ubiquitous timer chip NE555 (IC1) . Output of IC1 controls the solenoid valve through a 6V electromagnetic relay attached to J1.
Two LEDs (LED 1 & LED2) are added as system status indicators. SPDT switch S1 is the “Auto/Manual” Mode Selector. “Push – to – On” switch S2 can be used for manual operation of the faucet. Prototype tested with four 1.5V AA cells (1.5Vx4 = 6V).
Note:
Remember to set delay time & detection range of the system as low as possible by adjusting the preset pots P1 & P2 of the PIR sensor module. Removing the fresnel lens, collimation and screening by means of a piece of a suitable electrical conduit with a length of 2 to 3 cm is not a bad idea to reduce the field of view of the PIR sensor module. Place the jumper (JP) in “Normal” mode!
Why a PIR sensor based design? PIR sensor is small, inexpensive, low power, rugged,is easy to interface with, and is easy to use. When motion is detected the PIR sensor outputs a high signal on its output pin, which can either be read by an MCU or drive a transistor to switch a higher current load.
Their best feature is that they don’t wear out!
Parts:
SEN 1: PIR sensor module
T1: BC547
LED1: 5mm Green
LED2: 5mm Red
D1: 1N4007
IC1: NE555
R1, R2: 1K
R3: 100K
R4: 470R
C1,C2: 100nF
C3: 100uF/16V
S1: SPST On/Off
S2: Push -To – On
J1: 2-Pin male header
Relay: 6VDC /SPST Electromagnetic Relay

Schematic of the receiver circuit

A small, simple AM receiver project with only 3 transistors. This circuit can pick up medium wave stations in your area.
Description:

It can use general purpose transistors, and in this example there are 3 BC109C transistors. The schematic and BOM show a 200µH inductor and a trimmer capacitor 150-500pF, though these parts can be salvaged from an old AM radio, to preserve the directional nature of a tuning coil, and an adjustment knob (plate capacitor) that work well for radio reception.
The 120k resistor is for regenerative feedback between the Q2 NPN transistor and the input to the tank circuit. The value of this resistor is important to the performance of the entire AM receiver. In fact, it may be better to replace the fixed value with a variable resistor paired with a fixed resistor to adjust the oscillation and sensitivity. All the connections should be short to minimize interference.
Performance will vary depending on stray capacitance in your layout, the inductor winding/core/length, etc. Changing values of some of the capacitors, or adding them, as well as a potentiometer in the feedback loop can help with the performance of the receiver. With such a small circuit that is affected so much by its construction and its environment, a lot of hand tuning and experimentation will be fun, instructive, and possibly necessary to make it work best.

Click here for Parts List

Schematic of the receiver circuit

Robot voice circuit circuit diagram

Robot voice circuit circuit diagram

Some flexibility in the playback mode allows individual messages to be linked together; each recorded message is terminated by an EOM (End Of Message) flag when it is stored in the chip. Instead of storing complete phrases like ‘obstacle ahead’ for example it is more efficient to store ‘obstacle’ then ‘ahead’, ‘to the right’, ‘to the left’ and ‘behind’ and likewise for numbers ‘one’, ‘two’, ‘hundred’ ‘point’ etc allows voicing of the complete range of numbers from these basic elements.
The minimum playback circuit shown in uses the A0, PD, /CE and /EOM signals interfaced to the robot microcontroller. For playback PD is reset to ‘0’ and to play the first message a low pulse is given on /CE. With A0 at ‘0’ playback occurs at normal speed but with A0 at ‘1’ the chip enters ‘fast forward’ mode where it advances through the message at 800 times its normal playback speed. When the third message needs to follow the first for example, the processor sets A0 to ‘1’ and pulses /CE low to fast-forward through the second message, waiting for the /EOM flag to go low. Once this occurs A0 is reset to ‘0’ and a low pulse on /CE plays back the third message.
The /EOM output pulse can be less than 10 ms wide so it is better to use it to interrupt the processor rather than just poll its status.