After some time of no building activity, the dark afternoons and less busy week-ends has come finally. Perfect time of the season to build a new rig. See what is being done on my bench. I like this way of start, because of easy modelling a components layout. Say, that`s enough experiments with NE612. The heart of the receiver is popular Motorola c
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hip MC 3362. Not much Ham applications are available. That`s my pleasure to go. This is very convenient and gives opportunity to select best circuit, best value and best component. I have changed IF frequency as well as VFO frequency triple times. Finally remained on 8MHz RF and corresponding VFO, which seems to be very stable. I don`t have final schematic because there are so many ways to develope. My favourite "universal breadboard" has changed into protoboard, but I am trying to develope future printing circuit based on above "training". Every component is carefuly selected and placed. Schematic diagram is corrected in parallel. The biggest problem was the VFO stability. I had to recall experience of many Hams and myself to find a solution for drifting parameters of coil, capacitors and IC`s internal varactor diode. Compensation wasn`t easy but finally I used poly cap, T50-6 ( yellow core works better than red) and ceramic trimmer capacitor. The overall drift is very low. 170 Hz within first 5 minutes and less than 50Hz in following hours. I tried varactor tuned four crystal ladder filter for the first time. Works fine The Contest ended with satisfactory score - 312 QSOs, 34(!)zones and 82 countries only. This counts for 95k points. Just after the contest I decided to eventually finish prototyping and commence PC board project for future kit. Below you can see working prototype-clean. I worked OK1DSS today (11th of...
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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