It is a programable frequency multiplier, usually using digital logic integrated circuits. The synthesizer is aranged to multiply a reference frequency by a programable amount to achieve just about any frequency you want. If, for example you had a reference frequency of, say, 1KHz and a `programable multiplier` then you could program the multiplier to give you
Click here to download the full size of the above Circuit.
1KHz (X1), 3KHz (X3), 1. 025MHz (X1025), 98. 325MHz (X98325) or any other frequency you want. Sounds easy Actually, it is so easy, once you understand some of the basics. So let us start off by building a simple synthesizer that cover 3KHz to 4000KHz (4MHz). A Phase Locked Loop (PLL) consists of a Voltage Controlled Oscillator (VCO), the output frequency of which is monitored and controlled. An error voltage steers the VCO and brings it back onto the correct frequency. The error voltage is generated by a Phase Sensitive Detector (PSD) which compares the VCO frequency with a reference frequency. Consider the following block diagram: Here we have a 1KHz reference oscillator feeding the PSD Input-B, and a VCO feeding the PSD Input-A. The output of the PSD can be a square-wave and the difference between the positive pulse and the negative is averaged by the low-pass filter (LPF). This filtering results in a DC voltage that is fed back to the VCO to increase or decrease the frequency, as required. It is interesting to note that you can put a DC voltmeter on the DC control line and watch the DC vary. The voltage will vary if either the VCO centre-frequency changes or the reference frequency changes. This circuit alone can be built using a single CD4046, but without the reference oscillator. The reference osc input can then be an external connection to make a selection of usefull instruments, such as: The PSD signal input of 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: