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Electronics hobby
Designing and building a high power amplifier capable of driving low impedance (as low as 2 Ohm’s @ 50 Vpp) loads.
www.diyaudio.com/ see alias FdW
History of DIY audio
Audio DIY came to prominence in the 50s to 60s, as audio reproduction was relatively new and the technology "complex," audio reproduction equipment, and in particular high performance equipment, was not offered at the retail level. Kits and designs were available for consumers to build their own equipment. Famous vacuum tube kits from Dynaco, Heathkit, and McIntosh, as well as solid state (transistor) kits from Hafler allowed for consumers to build their own hi fidelity systems. Books and magazines were published which explained new concepts regarding the design and operation of vacuum tube and (later) transistor circuits.
While audio equipment has become easily accessible in the current day and age, there still exists an interest in building one's own equipment, including amplifiers, speakers, preamplifiers, and even CD players and turntables. Today, a network of companies, parts vendors, and on-line communities exist to foster this interest. DIY is especially active in loudspeaker and in tube amplification. Both are relatively simple to design and fabricate without access to sophisticated industrial equipment. Both enable the builder to pick and choose between various available parts, on matters of price as well as quality, allow for extensive experimentation, and offer the chance to use exotic or highly labor-intensive solutions, which would be expensive for a manufacturer to implement, but only require personal labor by the DIYer, which is a source of satisfaction to them.
I abandoned my Sony A-mount A99 in favor of the mirrorless and stablized full-frame A7II. Now I can use almost any old film camera lens on either my Olympus OMD, for its 2x crop factor reach, or the A7II for wider difficult lighting shots.
Started collecting and using some Minolta gear recently. This camera came together with a Vivitar 28mm f2.0, Minolta MD rokkor 35mm 1.8 and a Minolta MD rokkor 24-50mm f4. Obviously the previous owner enjoyed good lenses!
Hermagis Aplanat #6 f/6.8 270mm Ser II (s/n 30206) on Nikon D800
Sequence: Hermagis Aplanat #6 f/6.8 270mm Ser II (s/n 30206), 49-52mm step down ring, 52-42mm step down ring, M42 36–90mm focussing helicoid,M42 36–90mm focussing helicoid, M42 36–90mm focussing helicoid, M39-M42 step up, a M39 to Nikon F adapter, Nikon PN-11 spacer and Meike N-AF 46–68mm focussing helicoid.—As part of the Antique Camera Simulator project.
Shot with a not-so-tough-at-all, broken Olympus Tough TG-1.
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© Dirk HR Spennemann 2014, All Rights Reserved
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Rare point and shot 35mm camera which is basically a cut down version of the chinon 35EE compact rangefinder. Shares the same 38mm 1:2.7 lens but scale focus
A circuit board from the dead portable phone, with some processing to make it look a bit more interesting.
Rolleicord IV 1953 Heidosmat 3,2/75 mm Schneider Xenar 3,5/75 mm Blitzsynchronisation zwischen X und M umschaltbar
Just felt like taking another picture of my beloved iMac. It's so nice to use Handbrake without having to listen to the jet engine that is my MacBook's fan.
Coming in the front entrance and hanging a left down the first aisle (at least, I *think* this is the very first aisle), this is the view one would encounter. I kind of like those big overhead signs, but I feel certain the style as seen here is going to be changing, at least a little bit...
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Sam's Club, 2000-01 built, Goodman Rd. at Elmore Rd., Southaven MS
*
سـ أطول أحلامي في يومِ مـآ
بـ إذن الله
^^
بنتي الجديدة
nikkor 70-300
الله يطعمني خيرهـآ ويكفيني شرهـآ
,
Taken at a great event; the KPBX Recording and Video Sale. Dedicated to all those who are active in their local community. SPEAK OUT and be heard.
The Phottix Odin wireless TTL flash trigger has now been officially released.
Note that this photo shows a pre-release version of the Odin - the silk-screen labeling on the release version is slightly different.
Key features of the Odin include:
-much better range than Canon ST-E2 or Canon 580EX as master flash trigger (100m +)
-ETTL support for remote flashes
-even in manual mode, flash power output can be set from the Odin transmitter control unit
-can adjust zoom of remote flashes from Odin's TCU
-high-speed sync up to 1/8000 seconds
-second curtain flash sync
-uses commonly available AA batteries
-compatibility with Phottix Strato 4-in-1 trigger and the Strato II Multi trigger
For more info, read my review of the Odin.
strobist info: 580EX II at top right into reflective brolly, 580EX at top left into reflective brolly, both triggered by Canon ST-E2
Store closed January 2018
Austintown, OH. February 2017.
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I've finally got a grown-up camera! Say hello to my new Olympus OM-D E-M10 II.
Now I have to read the manual.
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.
Serial No. 325158. It's from 1943 from what i can find based on that serial number.
I would like to restore it, needs a new ground glass, the shutter in the lens is broken, the focal plane shutter fires but the speeds are all pretty much the same, the rangefinder is cloudy and the glass shroud is rather perished.
Other than the mechanical problems it's in pretty decent aesthetic condition.
Store closed summer 2017
Charlottesville, VA. May 2017.
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If you would like to use THIS picture in any sort of media elsewhere (such as newspaper or article), please send me a Flickrmail or send me an email at natehenderson6@gmail.com
35mm Range finder. By far my favorite rangefinder. Has plenty of speeds, great aperture range, built like a tank like the C3 but with a lot of upgrades.
Pictures taken with this camera:
This is what a notebook computer looks like in 2013. It's more commonly referred to as a notebook than a laptop. The first computer that I could remember was an Intel 386 back in the late 80's in Hong Kong. I've seen the explosion of the Internet along with the rise and fall of the phone line modems peaking at 56k speeds. I remember 13 years ago when AMD broke the 1GHz barrier with their Athlon. There was a time when CPU's could just be passively cooled. The emergence of wireless Ethernet was at times painful, but welcomed. This little machine with a diagonal of 11.6" no thicker than an inch is definitely more powerful than anything that I've cobbled together with parts. Quite nice to have so much computing power in a rather small package. The next technology improvement that I'm really looking forward to is for the widespread adoption of 300dpi LCD screens.
WEEK 28 – Raleigh-LaGrange “Secret” Walmart
Now for a shot of the entertainment section, focused on the electronics desk here. I was in the Southaven Walmart recently (would you believe I'm currently sitting on photos from two update: three Walmarts and six Krogers, not including either chain's Hernando store?!) and noticed they had gotten what I believe to be this exact gray counter, minus the logo and tagline on the front. If only they could have gotten the rest of this décor during the recent remodel instead of more Cheap Impact...
(c) 2016 Retail Retell
These places are public so these photos are too, but just as I tell where they came from, I'd appreciate if you'd say who :)