Project

# Title Team Members TA Documents Sponsor
1 Vacuum Tube Amplifier
Bingqian Ye
Qichen Jin
Zhen Qin other
proposal
Team members:
Qichen Jin, NetID: qjin4 (qjin4@illinois.edu)
Bingqian Ye, NetID: bye3 (bye3@illinois.edu)

Introduction and motive
Our goal is to mainly tackle on the amplifier portion of audio system. There are basically two types of amplifiers, solid state amplifier and vacuum amplifier. Since this project will only be three or four mouths, the design of solid state amplifier would involve with too much details on the Operational Amplifiers and dozens of feedback loops in high order, we decide to build vacuum tube amplifier, it is less complicated and more achievable in the short deadline. From the market perspective, there is no budget vacuum amplifier available in the US market. Besides, there is some low cost solid state amplifier available and some of them do their job really well (I.E. Onkyo M-5010). In order to test the performance of our amplifier, we would use a pair of cheap speakers for testing. We bought a pair of full range bookshelves drivers for testing. Since this is our first time dealing with vacuum tube circuit, we will mainly choose classical style circuit design. If we have more time, we would study more complicated vacuum tube circuits such as push-pull, and/or class-AB amplifiers. The details of plans for the vacuum tube amplifier is listed below:

Specification:
Class: Class-A amplifier. Reason: This kind of amplifier is the most simplest form. Though it consumes more power and output less power compare to class-B and class-AB, it might have a lower THD, as well as more friendly for us to design and build. Our designated speakers are bookshelves speakers, so high power is not needed here. We can also avoid any complication for using the cut-off region.
Implementation: Single-end. Reason: Technically a class-A amplifier can be implemented by either single-end or push-pull, but for the usual case and design simplicity, as well as limited bugged, we will use single-end as our system.
Choice of tubes: 6J1*2 as preamp, 6P1*2 as power amp. Reason: 6J1 and 6P1 are pretty cheap tubes that are widely available in Russia and China, and we found this kind of tubes have a typical I-V curve, and manageable voltage requirements (~250V anode, ~6.3V filament). In addition, there are also many successful commercial designs that use 6J1 and 6P1 as part of the amplification circuit.
Wattage: 5 - 10 W per channel for the 4 Ohms speakers, 100 - 300 mW per channel for ~300 Ohms headphones. Depending on the actual quality of the tubes, feedback loops factor, and avoid self-excitement (unstable system), we might adjust the power.

Primary Goals:
Frequency response: 60-18 kHz minimum.
Signal to noise ratio (SNR): ≥ 70 dB, the background noise should be neglectable compared to the sound.
Total harmonic distortion (THD): ≤ 3% @ 1 kHz.
Stereo isolation: ≥ 50 dB @ 1 kHz. The left and right channels need to visualize people about the sound coming from different distance as well as angles rather than just two speakers.
Good clarity and separation of frequencies of sound, for symphony, as least three different instruments can be heard at the exact time.

Other parameters:
Speaker sensitivity: 87 ± 3 dB.
Speaker impedance: 4 Ohms.
Speaker wattage: 15 W maximum.
Speaker frequency response: 50 - 20 kHz.
Headphone sensitivity: 90 dB.
Headphone impedance: 300 ohms.
Headphone wattage: 100 mW.
Headphone frequency response: 50 - 20 kHz.

S.I.P. (Smart Irrigation Project)

Jackson Lenz, James McMahon

S.I.P. (Smart Irrigation Project)

Featured Project

Jackson Lenz

James McMahon

Our project is to be a reliable, robust, and intelligent irrigation controller for use in areas where reliable weather prediction, water supply, and power supply are not found.

Upon completion of the project, our device will be able to determine the moisture level of the soil, the water level in a water tank, and the temperature, humidity, insolation, and barometric pressure of the environment. It will perform some processing on the observed environmental factors to determine if rain can be expected soon, Comparing this knowledge to the dampness of the soil and the amount of water in reserves will either trigger a command to begin irrigation or maintain a command to not irrigate the fields. This device will allow farmers to make much more efficient use of precious water and also avoid dehydrating crops to death.

In developing nations, power is also of concern because it is not as readily available as power here in the United States. For that reason, our device will incorporate several amp-hours of energy storage in the form of rechargeable, maintenance-free, lead acid batteries. These batteries will charge while power is available from the grid and discharge when power is no longer available. This will allow for uninterrupted control of irrigation. When power is available from the grid, our device will be powered by the grid. At other times, the batteries will supply the required power.

The project is titled S.I.P. because it will reduce water wasted and will be very power efficient (by extremely conservative estimates, able to run for 70 hours without input from the grid), thus sipping on both power and water.

We welcome all questions and comments regarding our project in its current form.

Thank you all very much for you time and consideration!