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A PCB from an old flatbed scanner. f2.0, to set the focus on the chip in the center of the circuit board
Former Caldor/Kmart
Target Salem MA
- Opened July 23, 2003
- Last New England Target with P01
- Target Greatland Style Layout
- P04 Prototype Exterior
- 97,000 Square Feet
IAP creative electronics lab; photo by Christopher Harting, 2009; cps creative_electronics; _DSC4800
IAP creative electronics lab; photo by Christopher Harting, 2009; cps creative_electronics; _DSC4763
IAP creative electronics lab; photo by Christopher Harting, 2009; cps creative_electronics; _DSC4757
IAP creative electronics lab; photo by Christopher Harting, 2009; cps creative_electronics; _DSC4767
IAP creative electronics lab; photo by Christopher Harting, 2009; cps creative_electronics; _DSC4810
A +/- 6V & +/- 12V 42A power supply from the 70's or so. Beautiful wiring, except for the raw 240v adjacent to low signal voltage through the connector plugging into the machine.
Simple Circuit board allowing control of mains voltage heating elements from 5V microcontroller IO pins using a relay and simple transistor amplifier
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If you would like to use this picture in any sort of form, please send me a Flickrmail or send me an email at natehenderson6@gmail.com.
On September 20-21, 2011, the Women's Board Maternity Committee sponsored this sale for all Hospital and University employees, students, visitors, families and friends in the Atrium.
the colour, she changes
but not in this picture
so don't wait
also you have to touch the coins
but you can't
so don't try
you'll just get the screen mucky
if you have mucky hands
if you don't (have mucky hands), then go ahead
but if you later find out that your hands are mucky, well, you pretty much only have yourself to blame
Electronics Hobby
From Wikipedia, the free encyclopedia
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"Power amplifier" redirects here. It is not to be confused with RF power amplifier.
Mission Cyrus 1 Hi Fi integrated audio amplifier (1984) [1]
An audio power amplifier is an electronic amplifier that amplifies low-power audio signals (signals composed primarily of frequencies between 20 - 20 000 Hz, the human range of hearing) to a level suitable for driving loudspeakers and is the final stage in a typical audio playback chain.
The preceding stages in such a chain are low power audio amplifiers which perform tasks like pre-amplification, equalization, tone control, mixing/effects, or audio sources like record players, CD players, and cassette players. Most audio power amplifiers require these low-level inputs to adhere to line levels.
While the input signal to an audio power amplifier may measure only a few hundred microwatts, its output may be tens, hundreds, or thousands of watts
en.wikipedia.org/wiki/Audio_power_amplifier
History[edit]
Three audio power amplifiers
The audio amplifier was invented in 1909 by Lee De Forest when he invented the triode vacuum tube. The triode was a three terminal device with a control grid that can modulate the flow of electrons from the filament to the plate. The triode vacuum amplifier was used to make the first AM radio.[2]
Early audio power amplifiers were based on vacuum tubes (also known as valves), and some of these achieved notably high quality (e.g., the Williamson amplifier of 1947-9). Most modern audio amplifiers are based on solid state devices (transistors such as BJTs, FETs and MOSFETs), but there are still some who prefer tube-based amplifiers, and the valve sound. Audio power amplifiers based on transistors became practical with the wide availability of inexpensive transistors in the late 1960s.
Design parameters[edit]
Key design parameters for audio power amplifiers are frequency response, gain, noise, and distortion. These are interdependent; increasing gain often leads to undesirable increases in noise and distortion. While negative feedback actually reduces the gain, it also reduces distortion. Most audio amplifiers are linear amplifiers operating in class AB.
Further developments in amplifier design[edit]
For some years following the introduction of solid state amplifiers, their perceived sound did not have the excellent audio quality of the best valve amplifiers (see valve audio amplifier). This led audiophiles to believe that valve sound had an intrinsic quality due to the vacuum tube technology itself. In 1972, Matti Otala demonstrated the origin of a previously unobserved form of distortion: transient intermodulation distortion (TIM), also called slew rate distortion. TIM distortion was found to occur during very rapid increases in amplifier output voltage.[3] TIM did not appear at steady state sine tone measurements, helping to hide it from design engineers prior to 1972. Problems with TIM distortion stem from reduced open loop frequency response of solid state amplifiers. Further works of Otala and other authors found the solution for TIM distortion, including increasing slew rate, decreasing preamp frequency bandwidth, and the insertion of a lag compensation circuit in the input stage of the amplifier.[4][5][6] In high quality modern amplifiers the open loop response is at least 20 kHz, canceling TIM distortion. However, TIM distortion is still present in most low price home quality power amplifiers.[citation needed]
The next step in advanced design was the Baxandall Theorem, created by Peter Baxandall in England.[7] This theorem introduced the concept of comparing the ratio between the input distortion and the output distortion of an amplifier. This new idea helped audio design engineers to better evaluate the distortion processes within an amplifier.
A close up of the GPS section of an M2R, Martlet 2's radio board.
The radio board features a uBlox MAX-M8Q GPS with an LNA+SAW on the input, a Radiometrix MTX2 which can either connect directly to the output or go via a 500mW RF power amplifier, and an isolated connection to a RockBLOCK Iridium satellite modem. It's all powered by an STM32F303CBT7 microcontroller.
Fore more details on the schematics, see: www.cusf.co.uk/2014/07/martlet-2-electronics-schematics/
The PCBs were sponsored by Cambridge Circuit company, thank you! The Radiometrix MTX2s were sponsored by Radiometrix, also a big thank you!
I finally got a dedicated workspace for my electronics and ham radio projects instead of just doing them on my computer desk.
Macro of some 'old school' electronics, meaning pre-surface mounted devices and computer chips. Circuit board from an old battery backup emergency light.
Okay, it's a mess-- but it's a functional mess! (As soon as I get a chance, these will be replaced by a nice set of printed circuit boards.)
This set of electronics controls the 3D fabricator. On the left is a Make Controller, which is actually just being used as a super-fancy four-channel servo controller. In the middle, towards the back, the X and Y axis servo motor driver boards are marked by their large heat sinks. Each of those has an AVR microcontroller that accepts a position command, decodes the quadrature signals from the encoder wheels that are on the motors, and controls the high-current output driver (on the heat sink). The two protoboards closer to the front are (left) a third AVR-based controller that controls the hot air heater through a solid state relay, and (right) the PCB from a standard hobby servo, modified to drive a relays that control the automotive jack that drives the Z axis of the printer. On the far right is the solid state relay for the heater, and behind it is a control box with the power relays for the Z axis.
Read more about the Evil Mad Scientist Laboratories 3D Fabricator Project here.