Flashing Lights for Planes and Helicopters

There are two sorts of lights on aircraft: red or white flashing lights, which are called ‘anti-collision lights’, and steady lights, red on the tip of the left wing, green on the tip of the right wing, and white at the tail, called ‘position lights’, which enable an observer to see if the aircraft is approaching or going away. On the tip of each wing, in addition to the steady lights, there may also be flashing white strobe lights. The position light simulator given here takes a few liberties with the real position lights, making them flash (it’s more fun!) and using a little trick to simulate the strobe effect.


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Flashing Lights for Planes and Helicopters

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Rev Counter for Mopeds

Older mopeds are not usually fitted with a rev counter, which is a bit of a shortcoming. The making or finding of a suitable indicator instrument or display is often the greatest obstacle for the hobbyist. The author of this circuit has devised a practical solution to this problem in the shape of a (cheap) bicycle computer. Such bicycle computer is easily attached to the handle-bars and it usually has a large and very readable display.
The moped engine’s generator is used to detect the rev speed. The generator is connected directly to the engine drive shaft and generates an AC voltage for the on-board electrical system. The frequency of this voltage corresponds with the rev speed of the engine. This frequency, however, is too high to be used directly by the bicycle computer. The solution for this is to divide the frequency of the signal by 16, using a binary counter of the type 7493, before connecting it to the cycle computer.

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Rev Counter for Mopeds

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The generator signal is first rectified by D1, R1 and D2 and then limited to 2.5 V. Transistor T1 turns it into a usable logic signal. Counter IC1 contains four flip-flips, one after the other, which divides the signal by 16. This signal drives, via T2, the white LED D3. LDR R6 reacts to the blinking LED and is connected to the cycle computer in place of the supplied wheel sensor.  The generator signal also sup-plies the power for the circuit. D4/C1 provide rectification and filtering, after which the voltage is regulated to 5 V byT3 and D4.
For a correct read-out (calibrated rev counter), the bicycle computer needs to be adjusted for a wheel circumference of 889 mm or 89 cm (wheel diameter 28 inch).  Make sure that when building the circuit it is suitably protected against vibration and moisture. Mount the LED and LDR directly opposite each other and keep in mind that they need to be well shielded from ambient light.

LM1812 Ultrasonic-Transceiver

The LM1812 is a complete ultrasonic transceiver on a chip designed for use in a variety of pulse-echo ranging applications. The chip operates by transmitting a burst of oscillations with a transducer, then using the same transducer to listen for a return echo. Ifan echo of sufficient amplitude is received, the LM1812 detector puts out a pulse of approximately the same width as the original burst. The closer the reflecting object, the earlier the return echo.

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LM1812 Ultrasonic-Transceiver

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Echos could be received immediately after the initial burst was transmitted, except for the fact that the transducer rings. When transmitting, the transducer is excited with several hundred volts peak to peak, and it operates in a loudspeaker mode. Then, when the LM1812 stops transmitting and begins to receive, the transducer continues to vibrate or ring, even though excitation has stopped. The transducer acts as a microphone and produces an ac signal initially the same amplitude as the transmit pulse. This signal dies away as is governed by the transducer"s damping factor, but as long as detectable ringing remains, the LM1812"s detector will be held on, masking any return echos.

Low Cost Garage Stop Light

A novel use of solar cells makes positioning your car in the garage rather easier than old tyres, a mirror, or a chalk mark.The six solar cells in figure 1 serve as power supply and as proximity sensor. They are commercially available at relative low cost. The voltage developed across potentiometer Pi is mainly dependent on the intensity of the light falling onto the cells. The circuit is only actuated when the main beam of one of the car's headlights shines direct onto the cells from a distance of about 200 mm (8 inches). The distance can be varied somewhat with P.


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Low Cost Garage Stop Light

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Under those conditions, the voltage developed across C1 is about 3 V, which is sufficient to trigger relaxation oscillator Ni. The BC547B is then switched on via buffer N2 so that D3 begins to lfash. Diodes Di and D2 provide an additional in-crease in the threshold of the circuit. The total voltage drop of 1.2 V across them ensures that the potential at pin I of the 4093 is always 1.2 V below the voltage developed by the solar cells. As the trip level of Ni lies at about 50 per cent of the supply voltage, the oscillator will only start when the supply voltage is higher than 2.4 V.
The circuit, including the solar cells, is best constructed on a small veroboard as shown in figure 3, and then fitted in a translucent or transparent manmade fibre case. The case is fitted onto the garage wall in a position where one of the car's headlights shines direct onto it. The LED is fitted onto the same wall, but a little higher so that it is in easy view of the driver of the car. When you drive into the garage, you must, of course, remember to switch on the main beam of your headlights!

Automatic Wiper Control

A continuously working wiper is a big problem when it is raining slightly.The wiper control given here makes the wiper to sweep at rates from 1S to 10 S.
The circuit is build around an astable multivibrator using NE 555.Here the output at pin 3 remains high for a time period set by R2 ,and low for a time period set by R3.The low output pulse drives the transistor pair to drive the wiper motor to make one sweeping cycle and waits for next low pulse to arrive for next sweep.The high going pulse at pin 3 determines how many time should wiper should sweep in a given period of time.

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Automatic Wiper Control

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Notes:

• Connect the circuit to 12V line from Vehicle and connect the wiper motor and wiper switch as shown in figure.
• For setting the device first find out how much time it is required for the wiper to complete one sweep cycle.Now adjust
• R3 such that wiper makes correct one sweep cycle.Fix R2 some where on the dash board.And now the system is ready to use.
• You can adjust the sweep rate of the wiper using R2 according to the intensity of rain.

Electronic Car Horn Circuit Diagram

An LM556 dual oscillator/timer, U1, configured as a two-tone oscillator drives U2, a dual 4-watt amplifier. One of the oscillators, pins 1 to 6, contained in U1 produces the upper frequency signal of about 200 Hz, while the second oscillator, pins 8 to 13, provides the lower frequency signal of about 140Hz.

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Electronic Car Horn Circuit Diagram

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Increase or decrease the frequencies by changing the values of C2 and C3. U1's outputs, pins 9 and 5, are connected to separate potentiometers to provide control over volume and balance. Each half of U2 produces 4W of audio that is delivered to two 8 ohms loudspeakers via capacitors C7 and C8.

Automatic Water Tank Filler Circuit Diagram

 

This circuit has been very useful in filling a header tank for a reticulated water supply on a farm. Eight troughs are supplied in different paddocks where a lack of water would have serious consequences for the stock. In the past, the tank had been filled daily by a time clock which was not successful. During hot weather, the stock would empty the tank on a regular basis and then be without water for several hours or the tank would overflow and flood the area if the weather was wet and the cattle did not drink much.

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Automatic Water Tank Filler Circuit Diagram

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 The circuit described has been used to maintain the level of water in the header tank within prescribed limits. It controls a 3HP submersible bore pump which has a high starting current, necessitating a solid-state relay sufficient to take the starting load. Two Darlington transistors, Q1 & Q3, in conjunction with Q2 & Q4, are connected to the upper and lower water sensors in the tank. Q2 & Q4 have a common 5.6kO load resistor and function as a NOR gate. The output of the NOR gate drives Q5 which activates relay RLY1.

Initially, when the water level is low, both sensors will be open-circuit, the NOR gate output will be high and the relay will be turned on. This causes the normally closed (NC) contacts of the relay to open and disconnect the lower sensor. However, the upper sensor will still be open circuit and the NOR gate output will be high, keeping the relay closed. The normally open (NO) contact of the relay will be closed to operate the solid-state relay RLY2 to run the pump.

This state continues until the water reaches the top sensor which will then drop the output from the NOR gate to 0V. The disables relay RLY1 and the pump is stopped. In practice the upper level sensor is just below the overflow from the tank and the lower sensor about half way up the tank. The sensor contacts are simply two stainless steel screws about 25mm apart and screwed through the poly tank walls. The wiring junctions on the side of the tank are protected by neutral-cure silicone sealant.