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Prototype of the 2N32 which was commercialised May Medium frequency. June RF amplifier for example used in the Symposium portable TV. July Prototype of the 2N33 which was commercialised May High frequency oscillator used in the Symposium portable TV. March Prototype of the 2N72 switching type which was developed on a Signal Corps Contract. My recollection was that the wires were phosphor-bronze. The fusing of the wires was accomplished by discharge of a capacitor between emitter and base then collector and base. The machine which formed these junctions was then used to check DC forward current gain beta.


While touring the operation one day I watched the junction formation operators work. Beside each machine were two plastic buckets.

The reject container was much larger than that for good parts. The potential transistors were encapsulated in clear plastic before junction formation. Apparently, the importance of light as a carrier generator wasn't of concern at that time. It wasn't long before RCA stopped making germanium transistors that way. We were asked to organize a major symposium in the fall, to which the hundreds of RCA licensees would be invited. As the producer of the key ingredient, the transistor, my group and I became directly involved. The Symposium was organised by Industrial Service Laboratory which was responsible for licensing and held at Princeton from November 18 th Unlike Bell Laboratories prior to RCA did not have an ambivalent attitude to its licensees: the laboratories were supported by royalties and RCA wanted its licensees to be successful.

We demonstrated 24 different applications, covering just about every conceivable type of electronic device using transistors, even including the first all-transistor television set except for the picture tube. For our licensees in the device field, we even set up a small transistor production line to show exactly how they were made. The production line consisted of three operators. The first carried out acid etching of the wafers; the second applied the indium dots and loaded them into a furnace and the third attached the leads.

Transistor royalty attended as Mueller recalls. His comment was that this was the first time he had really made a transistor and that he was very happy to do so. George Sziklai a senior applications engineer at Princeton thought it would be feasible. However, he met a lot of resistance because, after all, no transistors could operate anywhere near the frequencies that were necessary for a regular TV set. However, George persevered and the project was approved. The RF sections were built with point-contact transistors where the greatest challenge was the front end.

Point-contact transistors were used in the RF stages. A TA 50 Mhz was selected and while not stable was usable as a local oscillator. TAs were used in the first IF section 7. The greatest challenge was finding power transistors that would drive the yoke and withstand several hundred volts. We went through, maybe, transistors before we found two of them that would work to deflect the beams sufficiently for this device. Accelerating voltage was maybe one-third or one-fourth of what it was now, and of course the picture size was very small, but this was quite a feat to find transistors that would withstand the high voltage to make these deflections.

Sziklai pair basic circuit

To make power transistors using germanium required efficient heat conduction to keep the junction temperatures viable. RCA tried adding fins to the transistor case, attaching the base support directly to the metal case and filling the cans with toluene to improve conduction of heat from the junction to the case. Overall the television set had 37 transistors and represented the absolute limit of the technology in Picture shows: left a liquid filled transistor and right a design where the collector is connected directly to the can to improve heat transfer which later became common practise.

Giacoletto and joined RCA labs in as a research engineer. He later developed the hybrid-pi transistor for RCA. In the spirit of pushing all available boundaries, George Rose, a key figure in the development of the RCA point-contact transistor built a simple single transistor CW transmitter for the 2 metre band successfully communicating with local ham operators up to 25 miles away.

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This feat was first reported in the February edition of QST and covered comprehensively the following month. Performance on 2 metres Mhz required selected transistors. It was a correct decision because the point-contact device has disappeared altogether. Having been outdone in making the first units, I organized a crash program to find a new approach for quantity production.

By the end of , we had succeeded so well that became a revolutionary year in transistor work at RCA. But the alloy junction transistor could not deliver the performance necessary for a portable radio and it was necessary for RCA to invest more development effort in Charles Mueller was a key person associated with the development of the RCA alloy junction transistor. In he was transferred to the RCA semiconductor programme. If the transistor was going to come--and people were not sure that it was going to come at that time--this would be the one.

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Mueller was asked by Kurshan to lead a team to develop a reliable transistor that could operate reliably at broadcast frequencies and therefore be suitable for portable transistor radios. RCA opted for an alloy junction strategy based on published work by General Electric. It looked to us as if it were something that could be made in large quantities. The work started in January when Pankove tried to make a PN junction by diffusing antimony and aluminium into germanium. By June no progress towards useable junctions had been achieved and Mueller was assigned to the diffusion experiments. The approach adopted was to evaporate the appropriate donors or acceptors onto the germanium surface.

This approach was abandoned in September when Mueller tried alloying a small sphere of indium onto N-type germanium. This was the approach that General Electric had discovered and worked well. By the end of September Mueller had made 40 PN junctions through this approach. By December RCA was confident that transistors could be made by the alloy approach. Their development closely paralleled that undertaken by John Saby at General Electric, utilising indium dots that were alloyed to opposite faces of an N-type germanium wafer producing a PNP transistor after the alloying process.

How Electronic Switches Work for Noobs: Relays and Transistors

Small dots were needed: 0. This melted the indium which shrank into a sphere thanks to surface tension. The method was refined by injecting molten indium into an oil column from a syringe which functioned like a shot tower. The indium dots were graded by sieving. After making the first transistors at Princeton, pilot production was transferred to the Harrison tube division. Mueller began to spend a lot of time commuting between Princeton and Harrison. A production line was set up with 10 female operators that could make transistors per day.

The room was exceptionally dirty: so much so that there were dust particles as big as the indium dots! Lack of a clean room environment and air conditioning contributed to the high reject rate. Transistor characteristics were controlled by alloying temperature: Higher temperatures accelerates alloying from the emitter and collector side resulting from a thinner base region. Mueller reflecting on this time says:. Whereas point-contact transistors could be made with polycrystalline germanium, the alloy junction approach required wafers cut from single crystals. Thus RCA developed its technology for the production of single crystal germanium.

RCA developed sophisticated approaches to zone refining in the mid s. Instead of pulling a germanium crystal through a heated zone, they built a furnace with 34 individually heated cells each 25mm long arranged in three groups. A controller actuated a cell within each group in turn creating three heat waves that travelled along the crystal sweeping the impurities to one end.

Step 1: What Is a Relay

Ironically RCA found that defect free germanium would cause increased wetting of the germanium wafer leading to oversized junction area and hence increased collector capacitance and poor RF performance. Controlled wetting of the germanium wafer by the indium dots was an important issue in producing consistent transistors. RCA tried electroplating indium onto the wafers but found that the indium tended to agglomerate on melting.

Armstrong developed a method of plating the germanium with a metal such as gold which was readily wet by a melting indium dot applied to it.

The area defined by the gold determined the area of the junction. During the alloying process RCA found that some of the indium evaporated over the surface of the wafer potentially short circuiting the junctions. This was removed by etching. Alloy Junction Type. April PNP transistor. Resin case. Prototype of the 2N NPN transistor. NPN 1 watt transistor rated at volts.

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  7. July-December PNP symmetrical types same sized emitter and collector indium dots. In June RCA filed on its alloy junction technology.

    Sziklai Pair | Compound / Complementary | Electronics Notes

    A transistor body made from N-type monocrystalline germanium typically of ohm-cm resistivity for PNP transistors. The collector dot is applied first and adhered by firing at C for one minute. The emitter dot is applied and the wafer fired at C for minutes to obtain alloying and diffusion of the indium to the extent required. After nine years General Electric won the battle by proving that Saby had invented the alloy junction transistor before RCA.