Variable Speed ​​DC Motor Controller 12V

For more details can be seen from a series of Variable Speed ​​DC Motor Controller 12V follows.

Series Variable Speed ​​DC Motor Controller 12V This is one series that can be used to regulate speed DC12V motor with PWM technique. Series Variable Speed ​​DC Motor Controller 12V uses a 555 timer IC as a PWM pulse generator to regulate the motor speed DC12 Volt. DC motor speed control process performed by adjusting the potentiometer R1 lever which in principle is set High and Low pulse width of the PWM pulse.

Series Variable Speed ​​DC Motor Controller 12V above the power MOSFET drivers in the form of a IRFZ46N is directly associated with DC motors. Working voltage of this circuit can be adjusted according to needs-driven DC motor, this circuit can work from 3-18VDC.

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PIC16F873 Room temperature controller

On this page, I will introduce the room temperature controller with PIC. This equipment uses two temperature sensors, drives external equipment, and keeps the temperature of the room at preset temperature. The purpose of this equipment is for preventing room temperature going up with the heat of the computers. Electric cost will become high if an air-conditioner is always operated. Then, I made the equipment which adjusts the temperature of the room automatically using some ventilation fans. The function below preset temperature is a function attached moreover. I think that it can use for temperature control, such as a greenhouse.

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Reservoir Pump Controller

Reservoir Pump Controller Circuit Diagram. This schema operates an automotive windscreen washer pump to fill a 20-litre drum from a 205-litre water reservoir. The drum is suspended above a drip line, which irrigates a vegetable garden. Two stainless steel probes mounted in the drum act as sensors for the system. One probe is positioned at the high water mark, the other at about half-full. The pump power is switched by a 12V automotive relay (RLY1). Two op amps (IC1a & IC1b) connected as voltage comparators form the basis of the schema. 

Initially, assume a falling water level with the pump switched off. When the water level exposes the lower probe, the non-inverting input (pin 5) of IC1b rises to about 7.4V. With trimpot VR2 correctly adjusted, this will be higher than the voltage on pin 6. The output (pin 7) therefore swings high, biasing Q1 into conduction. This in turn causes Q4 to conduct, switching on the relay and starting the pump. 

In addition, when Q4 switches on it supplies base current to Q3 via a 6.8kO resistor. Initially, this current flows through the 47µF capacitor, but once its base-emitter voltage reaches about 0.6V, Q3 conducts. This action latches Q4 in the "on" state, as its base current can flow to ground via Q3 when Q1 stops conducting – which will occur when the rising water level reaches the low probe. When the water level reaches the high probe, the voltage on the non-inverting input (pin 2) of IC1a decreases markedly due to the conductivity of the water.

Reservoir Pump Controller Circuit Diagram

If trimpot VR1 is correctly adjusted, the output (pin 1) swings high, switching on Q2. This discharges the 47µF capacitor and robs Q3 of its base current, switching this transistor off. This in turn switches off Q4 and the relay. The zener diodes and 1kO series resistors at the probe inputs protect the op amp’s high impedance inputs from the effects of static discharge. The 47µF capacitor in parallel with the base-emitter junction of Q1 prevents the latching function from being activated when power is applied to the schema. The author’s setup is powered from an old car battery charged from a 12V solar panel.

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Unique Water Pump Controller

Unique Water Pump Controller Circuit diagram. Here is a simple solution for automatic pumping of water to the overhead tank. Unlike other water-level indicators,  it  does not use probes to detect the water level and hence there is no probe corrosion problem. It has no direct contact with water, so the chance of accidental leakage of electricity to the water tank is also eliminated. Two important advantages of the schema are that the water level never goes below a particular level and no modification in the water tank is required. 

Fig.1 Unique Water Pump Controller Circuit diagram

Fig. 1 shows the schema of the water-pump controller. The schema uses an LDR-white LEDs assembly to sense the water level. It forms a triggering switch to energise the relay for controlling the pump. The LDR-LEDs assembly (shown in Fig. 2) is fixed on the inner side of the cap  of  the  water tank without making contact with water. The light reflected from  the water tank is used to control the resistance of LDR1.

Fig 2 Sensor schema diagram

When the water level is high enough, light from the white LEDs (LED1 through LED3) reflects to fall on LDR1. This reduces the resistance of LDR1, increasing the voltage at the non-inverting input (pin 3)  of IC1. IC1  is used in the schema as a  voltage comparator. Resistors R4 and R5 form a potential divider to fix half of supply voltage to the inverting input of IC1. 

Normally, when the water tank is full, LDR1 gets more of reflected light because the distance between the water level and the face of LDR1 is minimal. When white light falls on LDR1, the voltage at the non-inverting input (pin 3) of IC1 increases and its output goes high. This high output makes pnp transistor T1 non-conducting and the relay remains de-energised. LED1 also remains ‘off.’ Since the water-pump power supply is connected to the normally-open (N/O)  contacts of  relay RL1, pumping is stopped.

When water level falls, the amount of  light reflected to LDR1 decreases and its resistance increases. This reduces the  voltage at pin 3 of IC1 and its output goes  low. This  low output from IC1 makes transistor T1 conduct. Relay RL1 energises to close the N/O  contacts and the motor  starts pumping water. LED1 glows to indicate the pumping of water. 

Fig.3 Sensor assembly

 

Assemble the schema on a general-purpose PCB and enclose in a suitable  cabinet. Solder the white LEDs-LDR1 assembly on a separate PCB and use a separate power supply for it. Mount LEDs behind the LDR. Otherwise, light from the LEDs will  affect the working of the schema. Connect LDR1 to the main schema board at ‘A’ and ‘B’ points. 

Fix the LEDs-LDR1 assembly on the inner side of the water-tank cap as shown in Fig.  3. Orient the LEDs and the LDR such that when the water tank is full, the light emitted from the LEDs and reflected  from the water surface falls directly on  LDR1.  The  distance between the upper level of water and the LEDs-LDR setup should be minimal, ensuring that water doesn’t touch  LDR1. Otherwise, the schema  will  not function properly. By using more white  LEDs, this  distance  can  be increased. Cover the LDR with a black tube to increase its sensitivity. 

You can fix the main unit at a convenient place and connect it to the LEDs-LDR  assembly through wire. Select the relay according to the horse-power (HP) of the water pump. After  arranging the setup (with  maximum water in the tank), adjust VR1 until LED1 stops glowing. In this state, the relay should de-energise. When the water level decreases, the relay automatically energises to connect mains to the motor and it starts pumping water.

Author :D.Mohan Kumar - Copyright: EFY

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