The 7th overtone of 18mhz (17m) is 144mhz (2m) smack dab in the CW region. Icarus a HAB project run on advertising revenue that seems successful and has launched many balloons with some awesome photos. Robert Harrison knows his stuff! Lessons in Electric Circuits A very good (free) textbook. Anyone starting to learn about electronics should start by skimming
Click here to download the full size of the above Circuit.
over relevant chapters of this text! 1W CW transmitter kit Although I don`t own one, I appreciate the kit and love the schematic. This guy uses a buffer chip (a 74HC04n, similar to a 74HC240 often used in QRP too) to act as an oscillator and small amplifier. The output is then further amplified by a 2n3866 transistor. 30M Solar QRSS transmitter such an inspiring project! This guy uses a buffer chip (74hc245) to amplify the output of CKOUT of a microcontroller clocked at the transmit frequency. The thing is solar powered, and has a unique temperature compensation mechanism which uses the chip`s built-in thermosensor to adjust its offset. I haven`t seen this technique used anywhere else in a QRP transmitter! Everything this man does is impressive! His QRSS section is wonderful, and I won`t detract from it by trying to describe it here. He also has a simple QRSS receiver circuit based upon a SA602, something I replicated (tuned front-end not shown) to operate my W4DFU QRSS Grabber at the University of Florida. MOSFET Switched Mode Amplifiers a wonderful document, read it multiple times! Transistors are traditionally used in many QRP circuits as amplifiers, but MOSFETs have some unique qualities which in many ways makes them easier to work with in simple circuits. I found this guide EXTREMELY helpful!
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.....
characters left: