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empire9876

empire9876

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I am an Optical Science and Engineering PHD major, Applied Physics MS, Mathematics/Statistics MS~ and Electro-Mechanics. I am selling all my past Electronic business inventory which were collected from nearly 23 US, Japan, German, British, New-Zealand, Norway etc manufacturers for which I was a warranty service center. I am reinventing myself so your help is greatly appreciated. The majority products are from ONKYO with which I had close working relationship.
I have had a dream of making products "MADE IN USA" for years. Now kids are grownup and everyone has their own nest, I am prepared to start a whole new venture of "Manufacturing" products in the US, Texas.
Location: United StatesMember since: Jul 13, 2004
Top Rated Sellerempire9876 is one of eBay's most reputable sellers. Consistently delivers outstanding customer service Learn more

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Last 12 months

Positive407- positive feedback in last 12 months
Neutral1- neutral feedback in last 12 months
Negative1- negative feedback in last 12 months

Detailed seller ratings

Average for the last 12 months
Accurate description
5.0
Reasonable shipping cost
4.8
Shipping speed
5.0
Communication
5.0

All feedback (1,996)

  • s***c (330)- Feedback left by buyer.
    Past 6 months
    Verified purchase
    Very Fast Shipping, Well Packaged, Item as Described, Perfect transaction A+.
  • i***s (2083)- Feedback left by buyer.
    Past 6 months
    Verified purchase
    Very Fast Shipping, Well Packaged, Item as Described, Smooth Transaction, AAAAA+++++
  • b***b (131)- Feedback left by buyer.
    Past year
    Verified purchase
    Stunning transaction! The item is better then described!! Shipped very fast and well packaged!!! empire9876 is one of the best sellers I have done business with!!!! An excellent communicator, extremely knowledgeable and willing to help if he can!!!!! I gladly give my highest recommendation and best of regards!!!!!! A+A+A+A+A+A+A+A+A+A+A+
  • a***m (514)- Feedback left by buyer.
    Past 6 months
    Verified purchase
    Just the parts that I was looking for very hard to find parts quick shipping packed well as described 5 star seller
  • i***d (127)- Feedback left by buyer.
    Past month
    Verified purchase
    Great Seller. He quickly corrected a minor problem with the shipping charges. All items received in new condition. Would buy again.
  • b***b (447)- Feedback left by buyer.
    Past 6 months
    Verified purchase
    shipping ok, items as described, A very recommended Seller
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Reviews (8)
DCA55 Peak Atlas Semiconductor Tester Transistor MOSFET Diode DCA 55 Analyzer
Jul 01, 2023
Using DCA55 with Vintage Transistors
This is not a tool any engineer in the right mind will use let alone specify. It is good tool perhaps for a garage work than it is for a serious electronic design nor service. I bought one with hopes of reducing turning ON and OFF my expensive instruments which did not help me in the long run as the device was useless on vintage components. ... Transistors come with different "TEST CONDITIONS" which this device does not address. The manufacturers of the transistors provide various specs for transistors but those specs are conditional on input voltage and current settings. ... In 2012 I posted problems with the device when testing "VINTAGE" components where it indicated all transistors as defective although same components when tested on Tektronix 7CT1N and Huntron 1005B tracker showed the transistors were good. Jez the company rep posted this :- The DCA55 will decide if the transistor under test is a darlington type if the base-emitter voltage is typically larger than 1.0V for a base test current of around 4mA. Additionally, if the transistor has built-in resistor shunts across the base-emitter juunction then the threshold is dropped to 0.80V typically. This means that it is possible that a silicon transistor can "look" like a darlington to the DCA55 if it's base-emitter voltage drop is a little larger than many modern silicon transistors. This is particularly true for vintage silicon transistors as their base-emitter junction is very ohmic (quite a soft knee). The pinout, the gain and the leakage current however are all still valid and the "darlington" message doesn't affect any of the measurements. ... From his answer, I understood they did not consider that under normal test condition the Collector voltage/drain supply need to be set according to a table data provided by the transistor manufacturer(s), rather than calculating backward to establish base voltage which is wrong. ... Furthermore, more often than not, my technicians take the result they get to conclude transistors are defective without looking up the data because they believe all "Test Conditions" must have been met by the device to arrive to lower hFE than expected which in itself indicative of lacking common sense. I always told my technicians, the real test of a device comes during operation because during the design an engineer have taken into consideration the large hFE (current gain) variations into account. This situations does not register in the mind of most new technicians with least experience especially when the component is VINTAGE. ... At the end I returned the DCA55 and also tried the 75 with graphics and gave up. While I like to sell my Tektronix and use these little devices, their ambiguity on vintage devices and other limitations have kept me at bay for now. .. I am not saying you should not own them, but caution on test result. For most transistor hFE you can almost get no less result from a DVM with transistor checker. ... I have attached a test result from three test devices based on a Vintage transistor 2SA722.
Oct 23, 2014
Great book
Great instructional book for both beginners or experienced machinists. Simple to follow. Technically informative and it is a kind of manual that never looses its application with time.
Mathematical Methods for Optical Physics and Engineering by Gregory J. Gbur (Eng
Dec 12, 2022
Very good book
As an Optical Engineering PHD student, I found this to be a great book written by a full professor at UNCC. It is written with students in mind.
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