This is a project that I always wanted to do, but managed to put off for a long time. It has been over a year in the doing. Partly because there are so many good phono preamps in existence and I was slightly concerned that it was beyond my design skills. It took over a year to get it up to my satisfaction. There were several iterations and lots of
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frustration along the way. My goal was to make a preamp that would not embarrass the builder with inferior performance. I used a number of commercial products for comparison. My thought was why bother to design and build something that was already available for a lower cost. As it turns out, it was not as inexpensive nor un-complicated as I first hoped. I wanted response within 0. 5 dBV of the RIAA curve, low distortion, and a signal to noise of about -90 dBV. The first two were easy, the signal to noise was not. I did a lot of research on the RIAA curve and the various problems that are inherent in phono preamps. I tried active, passive and a combination of active and passive equalizations. All work and all have positive features and all have negative features. I tried several configurations and tube types. The final design uses things I am familiar with. The input stage is a symmetrical SRPP. It feeds the passive equalization network. The second stage is nearly identical with the first and is direct coupled to the third stage which is a cathode follower. I eventually used Gold Pin JJ ECC83S in both of the SRPP stages and half of a ECC81 (12AT7) for the cathode follower. Gain is sufficient at 45 dB for me to use a high output MC cartridge (I use a Dynavector 10X5 with an alternate of a Denon DL-110) to drive a passive volume control to feed a pair of Oddblocks. The initial design tried using other tubes but none had...
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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