The power supply is just a 7812 voltage regulator followed by an op-amp set to 6V to create a half way supply voltage for the audio op-amp stages. A 12V regulator seems to be too high for a battery fed application. These 4 outputs are all followed by a op-amp set up as an integrator. and the R/C circuitry around these op-amps ensure a very soft transition to the next
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antenna element. A network of two resistors feeding the + inputs of the op-amps is used to bias the op-amps; the voltage on the + inputs is determining the output waveforms and therefore the resulting transition from one to the next antenna. This is quite important for normal operation; in existing designs very small input signals will not give a stable reading, and signals that are too big will clip in the last filter stages resulting in serious bearing deviations. Therefore, the automatic gain control in the PA8W Doppler is a valuable addition. That means that a constant audio signal exactly on frequency will hardly be affected by the capacitors that will already have been charged to the right voltage over some time. Only parts in the audio that deviate from average will be reduced extremely because the capacitors will have to be charged or discharged to the new value. All kinds of parameters, such as group delay in your receiver and phase shift in the RDF low pass filter stages will shift this point away from the truth, The output of the NAND poort should be connected via the 3M3 resistor to the base of the dimmer transistor to provide some schmitt-trigger action for a clean "freeze" of the last bearing. As soon as the AGC voltage is dropping below the "freezing point" the collector of the dimmer transistor will go up and the output of the NAND will go down, preventing the 40174 to be retriggered. A simple way to adjust...
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.....
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