The solar panels are operating at optimal parameters when they are at the perfect right angle to the sun. Unfortunately this is accomplished only if solar panels are rotated by the sun. This is the purpose of this diy solar tracker system. The solar tracker circuit uses a window comparator to maintain the motor in a idle state as long as the two LDRs are under the same illumination level. In this case, half the voltage is applied to the noninverting input of A1 and to the inverting input of A1. solar tracking components T1, T3 = BD239, BD139 T2, T4 = BD240, BD140 A1, A2 = 1/2 of LM324 Diodes = 1N4001 When the sun position is changing so does the illumination level on the LDRs and the input voltage for the window comparator is no longer half of the supply voltage thereby the output of the comparator generates informations for the motor that rotates the panels for tracking the sun. P1 and P2 are adjusted in such way that the motor stands still when the LDRs get the same amount of solar light. If less light reaches LDR2 than LDR1, the voltage in point A increases to more than half of the power supply voltage. As a result the output of A1 is HIGH and T1 and T4 transistors conduct. In this situation the motor is starting. If the angle of the solar light is changing again and the voltage in point A decreases at less than power supply voltage, the output of A2 goes HIGH and T3 and T2 transistors conduct. As a result the motor is rotating in opposite direction. For solar panels control is best to use small motors with a suitable voltage and a maximum working current of 300 mA. This solar tracker system is used for tracking the sun only in one plane, the horizontal one. If you want to track the solar light in the vertical plane you need to build a separate sun tracker circuit. This is a simple and practical analog solar panel tracker circuit. Using four LDR (light dependent resistor) as a sensor in detecting the light source arranged as illustrated. When the light hit the LDR in a certain position, it will activate the circuit and trigger the relay to turn the slewing motor in the right direction until the sensor is fully shaded under its cover stopping the motor to its rest condition.

Hard water has a high concentration of minerals, and of these calcium salts are the most troublesome. But there is a solution coming in form of a cheap diy water softener system built with the well-known 555 IC. Actually the price of this diy system is so low that even if this doesnt work you wont be upset. The working principle of the water softener is based on a theory from 1930 which states that an electromagnetic or electric field causes small crystals of calcium carbonate in the water to join together to form larger crystals. One of the methods to obtain a strong magnetic field is to put a powerful magnet (2.5 gauss) near the water pipe. The second method is the electronic one. Studying a water filter purchased from stores we found that it produces a frequency of about 15 kHz at an amplitude of 15V. The values of the coils are not known, but my guess is L1 has 9 turns and L2 has 7 turns. Actually you should consider this circuit as a theoretical one. Therefore this water softener system uses one 555 IC to obtain a rectangular signal that is applied to the water pipe by wrapping two coils with one open ending around it. The coils must have good isolation. Make sure to power the water softener from a isolated power supply because in some areas the water pipes are connected to ground.

If the 78XX regulator and T1 are mounted on the same heat sink then the transistor is thermally protected. The output voltage is dependent only on the type of the voltage regulator used in the circuit. With the components presented in the schematic the maximum output current is 2 A. T1 is BD242 but for different values of the output current you need to replace some components (download the table at the end). If higher values are necessary, some components must be changed according to the table presented in the excel file. For currents above 7 A then T1 must be replaced with 2 transistors (T1 and T1*) connected in parallel, each of them having a resistor in emitter, R1 and R1* respectively. Also the bridge rectifier is different.

RC Servos basically come in three different sizes (micro, standard, and giant) to accommodate the type of RC models they are being used in. All RC servos have a three wire connector. One wire supplies positive DC voltage (usually 5 V) . The second wire is for voltage ground (0V), and the third wire is the signal (control) wire. The servo motor can be moved to a desired angular position by sending PWM (pulse width modulated) signals on the signal (control) wire.Usually, a pulse of width varying from 1 millisecond to 2 milliseconds in a repeated time frame is sent to the servo for around 50 times in a second. The width of the pulse determines the angular position. For example, a pulse of 1 millisecond moves the servo towards 0, while a 2 milliseconds wide pulse would take it to 180. The pulse width for in between angular positions can be interpolated accordingly. Thus a pulse of width 1.5 milliseconds will shift the servo to 90. It must be noted that these values are only the estimations. The practical range of pulse width is 0.2ms to 2.5ms, and frequency is 20Hz to 60Hz. Notes Prototype was tested with a Tower Pro Micro Servo. Servo test socket J1 in the circuit is a standard 3-pin male header. In case of any difficulty, you can use 3 flying leads with alligator clips as test probes S1 is a Push-To-On switch works as a Test Switch LED 1 is added to indicate the output status of the tester Try to use a precision 4K7 trimpot as P1 Note that, here the control pulses have a maximum voltage near-equal to the input voltage (5V) of the tester circuit. This can be a problem if your servo expects a 3V control signal It is good to add a 100F/16V capacitor, as a buffer, across the 5V DC supply (VCC & Ground) Change the values of R1, P1, R3 and C2 if necessary/when demanded by the RC Servo under test. Before testing an RC servo, carefully refer its technical datasheet

Described here is a simple, inexpensive and useful circuit for electronics hobbyists. The circuit is nothing but a PCB drill speed controller, which can be used to control the speed of any 12VDC small pcb drilling units. Such portable units are now widely available, and even a hobbyist can make it without too much difficulty. In this circuit, the renowned timer chip LM555 (IC1) is used as a PWM circuit. The whole circuit can be powered from a standard 12VDC supply, capable of sourcing ample current to the PCB drill motor. As you may noted, power supply for the PWM circuit is down-converted and regulated with the help of a 3-pin fixed regulator chip LM7805 (IC2). This will improve the circuit stability. Precision 50K trimpot P1 is the variable drill speed controller. Finally, a logic-level power Mosfet IRL 530N (T1) is used as the output drive element. This IRL530N mosfet (available in TO-220 package) can handle current upto 27A! Fast switching and Low on-resistance RDS (on) are other attracting features. IRL 530N is universally preferred for all commercial-industrial applications at power dissipation levels to approximately 50 watts. Drill Speed Controller Notes PWM (Pulse Width Modulation) is an efficient way to vary the speed and power of electric DC motors. The described circuit can be used to vary the speed of small electric PCB drill.The circuits can quite easily be built on a standard prototyping board. The power component (IRL510N) must be connected to the power rails and the drill motor with quite thick wires and cables.As used here, a Power MOSFET motor driver is better than the traditional driver because it is working at a higher switch frequency, and this also avoids the unnecessary voltage drop and power loss Electrically a DC motor can be viewed as a series RL network with a voltage generator. The generator represents the back electromotive force (BEMF) generated by the motors rotation and which opposes the electromotive force of the supply. Diode D3 (1N4007) is added to protect the electronics from BEMF. Diode MBR 1645 is a better alternative STP22NE10L (100V/