The unit is based on a PHILIPS FM880 link transceiver which was originally supplied to a Telecom Australia specification for telephone applications in remote areas of Australia. The FM880 in turn is part of the family of equipment including the PHILIPS FM828/FM814 series of fixed and mobile transceivers. The main receiver and transmitter exciter b
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oards are identical in most cases and are surrounded with specialized boards and circuitry for the particular application. The VK6WIA modifications are therefore simply another variant of the versatile PHILIPS design, although a fundamental change has been made in that the system of modulation has been changed to direct FM of the exciter reference crystal oscillator. The inbuilt phase modulator on the original FM880 exciter board is unused. Other audio, power supply and control facilities have been added to provide the WIA Broadcast Officer with a transceiver designed to provide the regular news broadcast service. Extracts from the FM880 handbook, detailing receiver and transmitter circuit description, alignment instructions, circuit diagrams and board layouts are attached at Appendix I. 4. 1. Apply 13. 8 Volts to rear connector, connect antenna and attach microphone. Set all controls to max anticlockwise and toqqle switches to OFF (up). The DTMF / HL / Tone Switch should be on "HL". 4. 3. Advance Receiver AF gain by a small amount. Rotate Receiver SQL control until noise is heard. Set AF gain for a convenient level and adjust SQL for muting threshold. 4. 5. Advance the MIC gain and speak into the microphone without activating the PTT or TRANSMIT key. The microphone audio level should indicate on the VU meter. Set the MIC gain so that at the speaking level and distance to be used the VU meter on frequent peaks deflects to...
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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