The LED phototransistor light gate should be mounted about 1 to 2cm apart, in some kind of rigid housing. We mounted it on a piece of brass attached to the circuit board. The housing also needs to be able to fit the compass inside, and also not obscure the view of the needle, as you will need to be able to watch the compass while you are setting i
Click here to download the full size of the above Circuit.
t up. The coil we have suggested is actually two coils and we used them set up in parallel to work with each other (the diagonally opposite legs should be connected together), which is why there are two in the diagram. In the circuit we used (and the diagram above) the collector of the phototransistor was connected to the zero rail, and the emitter was connected to pin 2 of the op-amp. If your circuit does not work, try switching the legs over. When the circuit is built and double checked, then test the output of it (pin 6), it should be around (plus or minus) 10 volts or higher when there is nothing blocking the light, but drop to near zero volts when the path is blocked. Now you are ready for a test. Align the coil and the compass, so that the needle will block the light gate when it pointing East-West. The coil should be about half a centimetre from the end of the needle to start with. Now switch on the circuit, and the compass should swing round towards the coil a little. If this does not happen the chances are that the coil`s magnetic field is parallel to that of the compass, to rectify this you can turn the coil around, or switch the terminals of the coil, or turn the whole detector around. Once the coil is making the needle rotate a little way you need to insert the soft iron into the coil, very slowly. The needle should come further round until it is in the beam, where it should sit. If you do this too fast the...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
characters left: