Welcome to my website dedicated to vacuum tube amplifiers and high-efficiency speakers

etracer-軟體新增燈絲電壓緩啟動功能

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Written by 站長Chris Chang

Published: 06 September 2021

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比起已被額定燈絲電壓加熱完成的燈絲電阻，在室溫下真空管的燈絲具有更小的電阻值。當一隻待測真空管被插入etracer測試時，根據歐姆定律V=IR，較小的燈絲電阻會導致更高的電流流過燈絲，因此在此初始加熱過程燈絲上會散耗更大的功率。冷燈絲與熱燈絲之間的電阻值差異可以達到3至5倍，因此很多人擔心這個瞬間的功率峰值會損害珍貴的真空管。雖然所有的真空管在設計時都有考慮過承受這個功率峰值，減少這個功率峰值仍然是一個比較理想的做法。

etracer - etracer的高壓規格設定與零件選擇

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Written by 站長Chris Chang

Published: 11 January 2021

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前言
設計像etracer這樣的真空管測管機，有很多因素需要考慮，例如最高測試電壓，最高測試電流，最低負壓，燈絲電壓與電流範圍等等。理想上，我們希望測試電壓與測試電流越高越好，但是這些規格往往是互相牴觸的，例如在有限的類比/數位轉換器(ADC)解析度下，測試電流範圍越寬廣，測試精度就越差。還有一個很重要的因素，就是產品的價格定位，越高級的規格，往往伴隨著更大的體積，與更高的價格，俗話說：＂便宜無好貨＂，便是此理。對於工作在最高電壓達800V DC的etracer而言，所有的零件都必須經過仔細的考慮與選擇，以確保機器可以在未來長達數十年的時間裡正常工作。市面上有一些測管機的成品或是套件，雖然乍看之下便宜大碗，但是以我個人淺見，它們的零件選擇常有一些問題，規格不夠的零件，壽命堪慮不說，輕則燒機，重則傷人，買家豈可不慎乎？在此文章裡，我們將針對高壓這個方面，深入討論etracer的設計考量。

etracer PC控制軟體版本2.xx功能簡介

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Written by 站長Chris Chang

Published: 29 July 2018

Hits: 8451

基本架構簡介

etracer PC控制軟體主要有七種工作模式，切換方式為利用圖形區下方的七個標籤頁選擇。

前三個標籤[快速掃描]、[完整掃描]與[極端條件]提供三種基本的測試功能。[快速掃描]提供待測物在一靜態工作點附近的基本參數，這個測試類似傳統測管機如Hickok TV-7的測試方法。[完整掃描]提供在不同閘極偏壓下的屏極電壓-屏極電流曲線，如同真空管規格書上的曲線圖。[極端條件]測試待測物在極端電壓條件下的電流特性。

[測試組合]模式讓使用者可以任意組合上述三種基本測試模式，並加入待測物偵測與燈絲加熱計時，適合大量測試同一種真空管。

[燈絲陰極漏電]模式可測試燈絲到陰極之間的漏電流。

[基本參數]與[負載線]可以對完整掃描的資料作即時分析。

為何你需要一台高壓750V的測管機？

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Written by 站長Chris Chang

Published: 20 May 2018

Hits: 11012

本文是一篇廣告文，目的為推銷本人設計的etracer真空管測管機，內容偏頗不客觀，請謹慎閱讀。

臉書的etracer英文群組裡，有網友問到測管機有需要到750V高壓嗎？難道不能測到400V，再從那裏外插曲線嗎？乍聽之下似乎言之成理，不過仔細思考似乎又覺得哪裡不太對勁。以此類推，那測管機有需要做到400V嗎？做到200V其餘外插不是更簡單？阿，那乾脆做到100V好了，省了高壓麻煩。

用膝蓋想也知道，外插一定比內插不準確，畢竟是用過去的經驗，預測未來的趨勢，就跟股市一樣，多少人股海浮沉，獲利者希，即可知外插之不可信，報告完畢。

工作溫度對脈衝式測管機的影響

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Written by 站長Chris Chang

Published: 03 February 2018

Hits: 9039

不知道從何時開始，etracer與utracer這種靠電容短時間放電測試真空管的機器被歸類為脈衝式(pulse type)測管機。而對此類測管機最常聽到的評語就是：這種測管機的測試條件不是真空管的真實工作點，所以測出來會有誤差，不準確。乍聽之下，似乎頗有道理，不過這樣的評語到底正確嗎？誤差是多少1%？10%？多少的誤差算不準確？莊子天下篇有云：一尺之捶，日取其半，萬世不竭。意思是說把一節木杖每天切一半，可以永遠一直切下去。問題是，莊子是哲學家，他用想像來切木杖，如果給工匠或是工程師來切，就不是這麼回事了。對於儀器設計來說，不能量化的評語是沒有意義的，這篇文章要跟大家一起探討這個評語的準確性。

etracer測管機套件正式上市

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Written by 站長Chris Chang

Published: 21 November 2017

Hits: 17016

2022/4/10 修改價格

etracer測管機經過半年來的開發與測試，終於在今年(2017)十月開始小量出貨，台灣區售價是：

• 組裝跟測試完成的PCB： NT$26400
• Model-01鋁合金機箱與配件：NT$7500
• 明緯EPP-200-27電源供應器(限與機箱一起購買)：NT$1200

上列價格不含5%營業稅

以下為大家介紹etracer的基本架構與性能

50 single-ended amplifier overhaul--New wine in an old bottle

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Written by Administrator

Parent Category: Audio frequency circuits-en-gb

Published: 05 June 2016

Hits: 4951

Finally the work on his pair of amplifiers is done. Let's have a look on what's different..

 This is the new look. The places that use to hold UTC chokes are replaced by load-inductors and interstage transformers.

Something new under the sun--Longitudinal Direct Coupled Amplifier

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Written by 站長Chris Chang

Parent Category: Audio frequency circuits-en-gb

Published: 31 May 2016

Hits: 6499

Vacuum tubes have been invented for nearly 100 years. Honestly all possible circuits configurations are almost exhausted. About fifteen years ago, following the rise of internet, there used to be an electronics Periodical called theTube CAD Journal where many innovative circuits were published. Tube CAD Journal seems to cease publishing since 2003. Around the same time period another paper based Periodical, the Vacuum Tube Valley, stopped publishing after the chair editor Charlie Kittleson passed away. There were a total of 20 issues of Vacuum Tube Valley with good materials on vacuum tube circuits. Since then it was really quiet. That's why my eyes were wide-open when I see the Longitudinal Direct Couple Amplifier. In the rest of the article I use the acronym LDCA to represent the name of this circuit.

Longitudinal Direct Couple Amplifier, publish granted by Chris Strickland

Amoy 寶 landmine – explosion Jiang phishing Rubycon electronic solutions Capacitance

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Written by 站長Chris Chang

Parent Category: misc

Published: 17 May 2016

Hits: 4514

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Story, this is the start of model courses:

Single-ended 50 power amplifier modification notes--high negative voltage grid bias circuit

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Written by 站長Chris Chang

Parent Category: Audio frequency circuits-en-gb

Published: 01 May 2016

Hits: 4266

This pair of 50 SE amplifiers was built by me some 15 years ago. The circuit is very stable and during the years of service there wasn't much problem except one event 3 years ago. The problem was caused by one faulty 80 rectifier where the filament broke and fallen onto one of the plates. It caused a short-circuit from the high-voltage winding of the mains transformer to the ground. I was using a 3A fast blow fuse and the short-circuit current caused by the faulty rectifier wasn't high enough to blow the fuse. Consequently the transformer heated up and eventually blew up the winding. The transformer was carefully built by James Audio but apparently it can't withstand such high current for a long time. Ever since that event I became extremely cautious about safety. If you ever built a tube amplifier, ask yourself a question whether or not the amplifier will survive when a rectifier goes to short circuit. This is a common problem for the rectifiers with hanging filaments. And many people including me believe tubes with hanging filaments sound better.

TEAC VRDS 25 repair note-replacing the driving belts

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Written by 站長Chris Chang

Parent Category: Digital audio source and Digital Signal Processing

Published: 20 June 2013

Hits: 15173

I bought this TEAC VRDS 25 CD player at ebay about 15 years ago when I did my graduate study at University of Pennsylvania in US. I listed this CD players on the internet for sale a couple times with not so positive experiences. Since I don't need money that bad so I just keep it on the shelf. I rarely turn it on after I start messing around with my Studer A725 CD players.One day my friend Xiang visited me and we tried to compare many CD players. In the end we decided to give the VRDS 25 a try but the CD tray didn't open when plugged in. When the open button was pressed nothing happened except a motor noise. Looks like spending some money is inevitable.

As usual, I started by searching the web for discussions and service manuals. From the discussions I learned that it's most likely the belts. Then I started searching replacement belts and after 3 weeks I received a bag as pictured. I was almost saying the F word when I got this bag. The belt can be easily found at a local electronics store at around USD$1 and I paid EUR$10 for these. Let's just hope these imported belts last longer.

Germany sent skin brought in the future, but unfortunately does not mean Germany manufacture