The AT90S1200 RISC Microprocessor (AVR family) is a very neat component to program a PLL synthesizer or for doing other rather trivial tasks in a radio circuit. It is reasonably cheap, easy to program and a nice integrated development environment is available for free from the manufacturer ATMEL. And the best thing about it: It has an internal RC
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clock generator so it does not need a crystal, in fact it does not need any additional components at all. The internal oscillators frequency is somewhat temperature dependent, but for most applications it doesn`t really matter how fast exactly the processor works. The only problem is that it is not possible to activate this internal oscillator with one of the (homemade or cheap-to-buy) serial in-circuit programmers. (The fusebits are only accessible in the parallel programming mode. ) Atmel sells a variant called AT90S1200A that has the internal oscillator activated by default. Unfortunately it seems to be impossible to get this variant here in Germany and from folks in the US I have learned that it is available but more expensive in the US. The circuit published here is able to activate the so called RCEN (RC oscillator ENable) fuse bit which is non-volatile and will be set forever unless you put it in the circuits with another firmware to deactivate it. It uses another AT90S1200 (oh boy I love this smallest part of the AVR family) as a master that sends all the necessary signals to the slave (the one that has the RCEN bit set). The hardest part was actually to extract all the necessary signal sequences from the datasheet. (It took me a full weekend to really understand everything and build the circuit. ) The master has a crystal attached so it works in no special mode or such. The master socket can also be used to plug in...
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....
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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....
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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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