After some years i started using the NMS8280 again for HAM radio purpose. When sending a signal in the air, radio amateurs should always identify by giving their callsign, this is also the case for sending a video signal. I wrote a program using the WBASS assembler which shows a scrolltext, this can be downloaded here. Unfortunately the incoming
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video signal is first converted to RGB, and converted back later after superimposing. The PAL decoder in this MSX is not very good, the encoder to convert RGB to CVBS is quite okay. At first sight the picture improved by placing a capacitor over the filter just before the PAL decoder, this filter separates the colour (c) (4. 43MHz) signal from the luminance (y) signal. For the y path, the video signal is passed through a lowpass filter which starts attenuating around 3MHz. This gives loss in sharpness. I tried to improve this filter, but it`s not easy to keep the delay of the y and c path equal, and too high frequencies will give aliasing while digitizing. Another work around is to simply switch between the unconverted inputsignal and the signal coming from the MSX video processor after the PAL encoder. This can be done by a 4053 for example. Normally the internal PAL encoder from the MSX will switch between the RGB signal of the MSX and the RGB version of the incoming video signal. The MSX video processor (VDP) determines when to display the internal or external signal. When this signal is used to switch the CVBS signals with the 4053, we are done for 80%. The select signal from the VDP is related to the RGB output of the VDP, after converting to CVBS the signal will be delayed for about 200ns. A 74HC74 is used to delay this digital select signal 2 clock cycles of the DHCLK of the VDP, otherwise the 4053 would switch too...
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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