This National Radio Institute radio kit covers the AM broadcast band from 550 to 1700 KHz. The set was designed to be constructed as part of a radio course taught through NRI. In contrast with some other correspondence course kits such as a later NRI chassis, it uses a safe transformer power supply. Tubes are a 6BA6 RF amp, 6BE6 converter, 6BA6 IF amp, 12AU7 detector and first audio, 6AQ5
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audio out and 5Y3 rectifier. NRI was well-known as a correspondence school for electronic technician training. NRI also produced a line of kits such as test equipment and a simple Novice ham radio transmitter/ receiver under the NRI and Conar labels. I first thought the cabinet was an excellent home-brew job. After removing the chassis, I noticed a rubber stamp on the inside bottom of the cabinet. This was indeed an NRI-supplied cabinet which I am told was available at extra cost. The chassis has IF transformers of two different sizes, several large over-sized resistors, a 12AU7 (dual triode) in place of the usual 6AV6 for detector and audio preamp, a choke in the power supply as a partial PI filter, a negative power source for audio output tube bias, three 1000 ohm resistors in parallel to develop that bias, and some other unusual features. I was wondering if someone had substituted components or simply miswired a couple of items such as the power choke. It turns out that ALL of the unusual features were designed into the set. I obtained a paper copy from George K. of the 68 page NRI lesson set 7E1 for this radio titled "Practical Demonstrations of Radio-TV Fundamentals; Instructions for Experiments 61 to 70". The unusual parts were either recycled from previous experiments or were included for a series of tests conducted in the process of building the radio. The tests and experiments include a simulated series of induced...
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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