Decided to quench my curiosity and see if a PICAXE-18X chip running at 4Mhz. was capable of this application. I also wanted to have a go at a project from the ground up. Designing the circuit, drawing up the printed circuit board artwork, etching the circuit board, programming the PICAXE in BASIC and hooking up the circuit board to a couple of surplus VHF radios as a repeater. Being that I am only one of
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four amateur radio operators in a 300 mile radius that uses our NHRC-4 controlled 2 meter repeater here in the outback in North West Australia, it`s possible that I will never use this circuit. So I encourage anyone to make improvements to any part of this project. The audio section of this project is not my design but was found on another Amateur Radio Operators web site elsewhere on the net. Thanks K5LXP. Also, I think it was a featured article in the magazine "QST" about 10 years ago. So it seems to be the standard OpAmp audio circuit for a simple PIC approach to controlling a Amateur radio repeater. This project uses a MC145436 DTMF chip for remote control and remote program changes. This basic controller features standard features in many others repeater controllers. Adjustable Time Out Timer, adjustable ID Timer, Morse Code Id`er with 11 available spaces for the call, i. e. DE_XX#XXX/R, adjustable Hang Timer delay, 3 programmable Roger Beeps, 3 digit password, all programmed in decimal. not HEX! All programmable via DTMF tones once the "BASIC" program has been downloaded into the PICAXE chip with the program and defaults settings. It also ID`s to a small speaker if required. I found the Speaker Output handy while programming. There are 3 power MOSFETs as switches, 2 used and 1 spare. There are 9 status LED`s for such things as 5 volts OK, COR active, Morse ID, DTMF Tones OK, Mute DTMF Tones, Repeater Muted, PTT...
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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