--- title: Energizing a vacuum-tube flip-flop module from a 1948... description: A deep dive into the TR-3 trigger module from the 1948 IBM 604 Electronic Calculating Punch, one of the first programmable calculators using vacuum tubes. The... canonical: https://daily.dev/posts/energizing-a-vacuum-tube-flip-flop-module-from-a-1948-ibm-system-srore98wj twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Energizing a vacuum-tube flip-flop module from a 1948 IBM system | daily.dev og:description: A deep dive into the TR-3 trigger module from the 1948 IBM 604 Electronic Calculating Punch, one of the first programmable calculators using vacuum tubes. The... og:url: https://daily.dev/posts/energizing-a-vacuum-tube-flip-flop-module-from-a-1948-ibm-system-srore98wj og:image: https://api.daily.dev/og/posts/sRorE98Wj.png og:image:alt: Energizing a vacuum-tube flip-flop module from a 1948 IBM system og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Energizing a vacuum-tube flip-flop module from a 1948 IBM system **[Hacker News](https://daily.dev/sources/hn)** · 17 min read · 0 upvotes · 0 comments ## Summary A deep dive into the TR-3 trigger module from the 1948 IBM 604 Electronic Calculating Punch, one of the first programmable calculators using vacuum tubes. The post covers how vacuum tube triodes work, how two inverters form a flip-flop (trigger) circuit, the reverse-engineered schematic of the TR-3 module, and a live demonstration powering the module. Historical context traces the flip-flop from the 1918 Eccles-Jordan circuit through ENIAC and IBM's BCD decimal counter patent to modern transistor-based flip-flops used by the millions in today's CPUs. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Community take How the wider developer community reacted, aggregated from 2 discussions and 12 comments across hackernews (as of 2026-08-05). **TL;DR:** Commenters are genuinely engaged and appreciative of the historical deep-dive, contributing additional context about vacuum tube failure rates, safety, and a rich timeline of early digital circuit history that the post glossed over. **Sentiment:** 75% positive · 20% mixed · 5% skeptical **The case for** - A commenter with deep historical knowledge filled in a detailed timeline of pre-WWII advances in digital circuits (thyratrons, binary counters, Schmitt trigger) that enriches the post's narrative. - The modular, easy-to-replace design of vacuum tube systems is noted as a practical engineering response to manufacturing variability and reliability concerns. - Germanium diodes, not the tubes themselves, are highlighted as the more common failure point in these early systems — a counterintuitive and interesting detail. **The pushback** - The post skips over significant pre-WWII developments in electronic digital circuits, leaving a notable gap in the historical account. **By community** - hackernews (positive): Enthusiastic engagement with both the technical and historical content, with commenters actively supplementing and correcting the post's historical timeline. **Hottest debate:** Whether a moon landing would have been feasible without integrated circuits, given the intermediate role of discrete transistor logic. **Open questions** - What was the actual failure rate of vacuum tubes in production IBM 604 systems? - How dangerous was it to service these machines given the high-voltage plate rails? - Could the Apollo program have succeeded using only discrete transistor logic, without ICs? **Highlights** > Thanks for another interesting article. Because you have skipped quickly over the decade before WWII when there were great advances in designing digital circuits with vacuum tubes, mostly in the UK, which have lead directly to the electronic circuits used in the British Colossus and in the US Atanasoff-Berry computer, and then in ENIAC, I want to fill in the gap between your 2 sentences: > The Eccles-Jordan trigger eventually led to digital counters. In 1939, ... After the Eccles-Jordan trigger mentioned by you, the following important steps were: 1929-07: “Hot-Cathode Thyratrons. Part II”, Albert W. Hull, where the inventor of thyratrons (at General Electric) describes a bistable circuit made with a pair of thyratrons, the second such circuit after the Eccles-Jordan trigger. 1931-01: “Note on the use of a thyratron with a Geiger counter”, N. A. de Bruyne and H. C. Webster, where it is suggested that the pulses produced by the Geiger counters for detecting radiation in nuclear physics experiments can be counted with electronic counters using thyratrons, since the existing mechanical counters were too slow for counting such pulses. 1931-07-02: “The Use of Thyratrons for High Speed Automatic Counting of Physical Phenomena”, Charles Eryl Wynn-Williams, where the first electronic digital counter is described. This counter was made with thyratrons and it was a decimal counter. For each decimal digit, a ring counter with 10 thyratrons was used. So the ring counter is the second kind of digital electronic circuit, after the simple bistable. 1932-05-02: “A Thyratron Scale-of-Two Automatic Counter”, Charles Eryl Wynn-Williams, where the first binary counter is described. It was also made with thyratrons, but it was an improvement over the decimal counter with ring counters per digit, as it required much less thyratrons and it was also more reliable. 1937-10: “A Scale-of-Two High-Speed Counter Using Hard Vacuum Triodes”, W. B. Lewis, where the first binary counter with vacuum tubes was described. This was an improvement over the counters with thyratrons, being much faster. 1938-01: “A Thermionic Trigger”, Otto H. Schmitt, where the Schmitt trigger made with vacuum tubes was described. The Eccles-Jordan trigger (a.k.a. R-S bistable) and the Schmitt trigger are 2 fundamental kinds of bistable circuits (i.e. the 3 values needed at the input of a bistable circuit, set, reset and keep the current value, can be encoded either with 2 binary inputs, as in the Eccles-Jordan trigger, or with 1 ternary input, as in the Schmitt trigger). Schmitt was American, but he invented the Schmitt trigger while working in the UK, where before WWII most of the work related to electronic digital circuits was done, mainly for applications in nuclear physics research. > — [adrian\_b on hackernews](https://news.ycombinator.com/item?id=49186485) > Over on Youtube the Usagi Electric channel has several videos about reviving old vacuum tube computers and one of the interesting aspects is that tube failures are much less of an issue than the germanium diodes. The tubes are large and dramatic, but they're heavily outnumbered by the diodes. It was such a problem that the company built specialized test equipment that could identify bad diodes on the cards. > — [jandrese on hackernews](https://news.ycombinator.com/item?id=49187677) > > I'm also curious, if the cathode was grounded to the machine frame, how dangerous was it to do work on those machines? When ground means earth, then: The chassis isn't dangerous at all. Its potential relative to other nearby things that are also connected to earth is ~0v. When that's used as a supply rail (like for the cathode), it still works fine. It's still tied to earth. You don't want to put any of your dinguses betwixt that and the +150v plate rail, but... I mean. :) > — [ssl-3 on hackernews](https://news.ycombinator.com/item?id=49187798) > Author here. I've powered up another tube module from the IBM 604, so let me know if you have questions... > — [kens on hackernews · 1 comments](https://news.ycombinator.com/item?id=49125632) **Source threads** - [hackernews](https://news.ycombinator.com/item?id=49125602) · 35 points · 10 comments - [hackernews](https://news.ycombinator.com/item?id=49147721) · 3 points · 2 comments ## Similar posts on daily.dev - [Energizing A Vacuum Tube Flip-Flop Module Of The IBM 604](https://daily.dev/posts/energizing-a-vacuum-tube-flip-flop-module-of-the-ibm-604-ktvr5ua7q) · Hackaday · 0 upvotes · 0 comments - [Powering Up A Pluggable Module From The 1948 IBM 604 Electronic Calculator](https://daily.dev/posts/powering-up-a-pluggable-module-from-the-1948-ibm-604-electronic-calculator-tjfbmopcs) · Hackaday · 0 upvotes · 0 comments - [A Vacuum Tube Computer For The Home](https://daily.dev/posts/a-vacuum-tube-computer-for-the-home-7xdfchmgw) · Hackaday · 0 upvotes · 0 comments - [Random adventures in electronics](https://daily.dev/posts/random-adventures-in-electronics-hxvfmbfss) · Two Stop Bits · 0 upvotes · 0 comments --- Tags: [#ibm](https://daily.dev/tags/ibm), [#computing-history](https://daily.dev/tags/computing-history) [View this post on daily.dev](https://daily.dev/posts/energizing-a-vacuum-tube-flip-flop-module-from-a-1948-ibm-system-srore98wj) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Energizing a vacuum-tube flip-flop module from a 1948 IBM system","url":"https://daily.dev/posts/energizing-a-vacuum-tube-flip-flop-module-from-a-1948-ibm-system-srore98wj","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/energizing-a-vacuum-tube-flip-flop-module-from-a-1948-ibm-system-srore98wj"},"datePublished":"2026-08-05T18:44:02.255Z","dateModified":"2026-08-05T19:46:09.353Z","description":"A deep dive into the TR-3 trigger module from the 1948 IBM 604 Electronic Calculating Punch, one of the first programmable calculators using vacuum tubes. 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