In the early 1970's, I was a tech at Control Data Corporation. They made a CRT Terminal for connecting to mainframe computers.  The power supply in it was totally analog and used 2N3055 for pass transistors.  There was also a zener across the 5 volt output that would trigger if a pass transistor failed and blow a fuse to cut off the output.  I probably repaired and tested over 5,000 of them during my tenure.

For those of us who grew up in the 1960' and 70's the 2N 3055 was the mainstay of audio  power amplifiers. In 1975 I built the Linslyhood 100watt stereo amplifier from a kit supplied at Radio TV and electronics in Johannesburg South Africa. Not all 2N 3055 worked as replacements in a blown Amplifier and I soon identified which replacements worked. The 2N 3055 that had a solid shinny large can usually worked well irrespective of the brand name, but the type that had a shalow aluminium top were usualy unsuitable as they would either blow at high volume or produce a very distorted sound.

An autopilot for planes used them in the 1970’s.

I still fix those old things to this day. Awesome old things stood the test of time

A little more on Gordon Teal. He lived in the Denver area and was a member of the Denver Astronomical Society in the late 1990s. My last picture of him was in 2001 at a camping star party. He loved to try out the latest gadgets and make some in his shop. The younger members of my club called him "Gordo" without realizing his contribution to the development of the early semiconductors. He died in 2003 age 95.

The first powersupply I built had a 2N3053 - 3054 and 3055 transistor setup. I still use it now, 35 years later.

I think the BC109 was less exciting but much more of an influence on electronics. Where would the 2N3055 be without it?

The video is wrong about the origin of the 2N2055's package.  It was designed to fit existing valve socket cutouts on radio Chassis', so no extra tooling required.
Additionally, the pins will also fit into a B9G valve socket which helped protect the transistor form heat surges during soldering with the huge soldering-irons of the day.
I was there and saw it all!

Built several amplifiers over the years, using this component.

Back in the 90’s We designed and manufactured 1000W Class AB Amplifiers that had 15 2N3055 / MJ2955’s pairs in its output stage. Mounted in a convection cooled 19” NEMA Chassis. With six channels one version put out 3Kw in a 6U Chassis with convection cooling. We designed the largest finned custom heatsinks that could be pushed through an extrusion die. The amp could drive a 1 ohm load at 10Hz up to 20KHz with a THD of 0.15% at full power, all channels driven and maintain a -105Db noise floor. The amps were impossible to clip.
Not bad for a design that started in a 1972 RCA Bipolar Transistor Data Book. The amps were feed by a linear power supply built around 1.8KVA (or larger) Toroidal Transformers and 300,000UF Capacitance per rail with +/- 80V rails.

It's sad, but my favourite transistor. So much power for so little money.

There is a 2N3055 and MJ2955 in my CBS color TV replica DC motor drive amplifier. Sitting not 6 feet away in my bookcase. I've been using 3055s in many of my designs since the late 1970s.


NOTE: Cut the lid off of your 3055 and you have an instant photo cell. From my high school electronics teacher, Robert Wagener, RBUHS, 1975 and 76 for me. Rest in peace Bob. You rocked!

In college we would drive to a nearby town which housed an Army base. Going into the road to the base were pawn shops. The Army soldiers coming back from Vietnam would buy high end stereo amps coming from Japan from the base exchange (PX).  They would sell them to the pawn shop after returning if they needed money. If the amp didn’t work the shop would sell them for almost nothing (they didn’t find out about this until after the purchase).  As engineering students we could buy the amps or receivers with an audio channel not working and take them back for repair.  In every case the 2N3055 was blown.  So for the cost of a single part and some silicon grease we would have an expensive stereo working again!  So long ago, but still on my mind.

Ah yes the 2N3055, I was in a remote northern area and one of the linear power supplies was not working on a new computer system due to mechanical damage.  I asked where the TV repair place was and asked for the biggest transistor they had, and it was a 2N3055.  Dropped it in the power supply and the system worked for many years after that.
It was the middle of winter, (-40) so we had to thaw the system out in the office for a couple of days before applying power...

I used these for audio amplifier output stages, usually transformer driven. Things got MUCH better, when I discovered the PNP complement, the 2N2955. Complementary symmetrical split power supplied output stages started pumping out upwards of 80 watts RMS into low impedance loads. (4 Ohm speakers) Back then, the 3055 was rated at 119 watts, and had a smaller chip, than the 2955, which was rated at 150 watts. They had the same current gain, but the PNP was slower, but, could handle more wattage. The complimentary pair allowed me to do away with drive transformers, allowing unlimited low frequency response, all the way down to DC.

They look like the output transistors on the rear of the Hearhkit and Knightkit stereo amps I put together in the 1960s, that eliminated the tube heat and the weight of the large output transformers of vacuum tube amps.  They made stereos affordable.

Our real workhorse was the Delco DTS423.  This was a bulletproof 400+volt TO3, and was used universally for CRT drivers, Audio amps, Video amps, power conversion, motor drivers, etc.  We paralled dozens to make multi-kilowatt amplifiers.  I believe they were originally targeted to provide high voltage power for car radios, which still used vacuum tubes, and had mechanical vibrators to convert the DC battery into HV for the tubes.

4:02: I like the way they advertised "eight transistors" on the handheld radio. This was considered a selling feature. Nowadays radios have many more with digital tuning, amplifier chips etc.

When I first started work in 1976, I was training as a Radio Technician in the New Zealand Post Office, Telecom section. One project nearly everyone did was Capacitor Discharge Igniton for our cars. That used two 2N3055 in a flip flop driving the 12 volt secondary side of a 230 to 12 volt ( centretap) transformer. Not sure about the size, maybe 50 VA.

Needless to say it was not uncommon to test our projects on Post Office vehicles.  They really did increase the performance of any engine using the standard points, ignition coil, and distibutor.

I came across the 2N3055 sometime towards the end of my electronics apprenticeship, 1965 to 70. It certainly was a game changer after having to use germanium OC35 etc. and justifiably became an industry standard. I have collected a lot of junk over my life time, including a pile of 2N3055s and have to think about decluttering and how to minimise the mess I will leave to my kids! It will be difficult to dispose of items like my 2N3055s as they are part of my soul (for want of a better phrase) thinking back to when it became so much easier to design circuits with them as opposed to the fragile germanium transistors.

Most "electronic" people that grew up in the 70s and early 80s knew that transistor and its basic data by heart - even over here in Germany. When I was in re-education for an electronic technician (from an architectures draftsman - by the way) between 1985 and early 1987 we built a small 1.5A regulated bench power supply at some point including the matching case from aluminium and it had - drum-roll - a 2N3055 as main regulator. I still have it, I still use it and it still works fine.
And - in my private repair shop - I am currently revising a 1969 Grundig SV-200 stereo amplifier, which uses eight of them. Two in pairs, two pairs in a quasi-complementary setup and four pairs in total for a 50-Watt-per-channel (Sine - at 4 Ohms) stereo amplifier. Each pair needs to have tight tolerances and that amp came with a flea-circus of non-matching transistors installed after a massive failure and amateurish repair attempt. I bought 20 OnSemi 2N3055 (from Mouser) - and measured out the closest 8 of these with my trusty bench power supply and two milliampere meters to get realistic amplification numbers to match each pair. The manual says "transistors are tested at a bias of 0.5A collector current and 4V across emitter and collector". The unit is still in the healing process, since the fault it went through caused a lot hidden damage - and the 1969 Grundig printboards with its fragile copper plating is a pain to work with.

Thanks for the video !