Schematic Diagram: water

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Friday, November 14, 2014

Automatic Water Tap Faucet Valve Controller

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 6V DC powered smart faucet controller circuit.

Schematic of the Water Valve Controller Circuit

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.

Parts List

•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

Thursday, August 7, 2014

Pump Controller For Solar Hot Water System

This schema optimises the operation of a solar hot water system. When the water in the solar collector is hotter than the storage tank, the pump runs. The schema comprises two LM335Z temperature sensors, a comparator and Mosfet. Sensor 1 connects to the solar collector panel while Sensor 2 connects to the hot water panel. Each sensor includes a trimpot to allow adjustment of the output level. In practice, VR1 and VR2 are adjusted so that both Sensor 1 and Sensor 2 have the same output voltage when they are at the same temperature. The Sensor outputs are monitored using comparator IC1.

When Sensor 1 produces a higher voltage than Sensor 2, which means that sensor 1 is at a higher temperature, pin 1 of IC1 goes high and drives the gate of Mosfet Q1. This in turn drives the pump motor. IC1 includes hysteresis so that the output does not oscillate when both sensors are producing a similar voltage. Hysteresis comprises the 1MO feedback resistor between output pin 1 and non-inverting input pin 3 and the input 1kO resistor. This provides a nominal 12mV hysteresis so that voltage at Sensor 1 or Sensor 2 must differ by 12mV for changes in the comparator output to occur.

Circuit diagram:

Pump Controller For Solar Hot Water System

Since the outputs of Sensor 1 and Sensor 2 change by about 10mV/°C, we could say that there is a degree of hysteresis in the comparator. Note that IC1 is a dual comparator with the second unit unused. Its inputs are tied to ground and pin 2 of IC1 respectively. This sets the pin 7 output high. Since the output is an open collector, it will be at a high impedance. Mosfet Q1 is rated at 60A and 60V and is suitable for driving inductive loads due to its avalanche suppression capability. This clamps any inductively induced voltages exceeding the voltage rating of the Mosfet.

The sensors are adjusted initially with both measuring the same temperature. This can be done at room temperature; adjust the trimpots so that the voltage between ground and the positive terminal reads the same for both sensors. If you wish, the sensors can be set to 10mV/°C change with the output referred to the Kelvin scale which is 273K at 0°C. So at 25°C, the sensor output should be set to (273 + 25 = 298) x 10mV or 2.98V.

Note:

The sensors will produce incorrect outputs if their leads are exposed to moisture and they should be protected with some neutral cure silicone sealant. The sensors can be mounted by clamping them directly to the outside surface of the solar collector and on an uninsulated section of the storage tank. The thermostat housing is usually a good position on the storage tank.

Source by : Streampowers