Of course, the battery was “not included.” The TR-1 pocket radio was introduced just before Christmas 1954 and sold for $49.95. Options included a leather case for $3.95 and an earphone for $7.50. An early advertisement is shown in Figure 1.įIGURE 1. Early advertisement for the TR-1.ĭespite its high price, Regency sold the first run of about 100,400 TR-1s before introducing the TR-1G (which was re-designed with a PNP output transistor) in 1956. The radio I’m restoring in this article ( Figure 2) was featured on an episode of the PBS series “History Detectives.” There are a number of good websites to learn the history of the TR-1, and one of the most complete is The site is run by Don Pies, the son of Regency co-founder John Pies. The question for the ‘detectives’ was whether this was the oldest transistor radio in existence. The question really was never answered because the actual production serial number on the commemorative TR-1 they found was not revealed.Īfter having the radio featured on the program, I started to wonder what it actually sounded like 62 years ago. Sony transistor radio schematic serial number# Starting around 1960, the market was flooded with six-transistor pocket radios - with many of those made for American companies. The 1954 TR-1 had only four transistors with a single audio stage driving the speaker, while the later six-transistor units invariably had an audio amp stage following the volume control and feeding push-pull outputs through a driver transformer. The speaker in the TR-1 was a 2.75” Jensen - larger than most of the ‘60s pocket radios - so it might sound okay. Like most of the TR-1 parts, it was probably the smallest speaker Jensen made at the time. I decided to restore it just so I could hear how it sounded. A schematic of the TR-1 is shown in Figure 3 with the four electrolytic capacitors highlighted (more on this later) the chassis of my unit is shown in Figure 4.įIGURE 4. AssessmentĪ Regency TR-1 in average condition usually sells for several hundred dollars on auction sites. A rare pearlescent blue unit sold in 2000 for $3,200. None are really expected to operate, only to ‘show’ in collections. My unit - perhaps one of the oldest transistor radios in the world (based on the low 2076 serial number) - required careful handling. I expected all four electrolytic capacitors to be open or shorted. What I found (in addition to that) was one shorted transistor and an open primary on the output transformer. Obviously, a “parts” unit was needed to proceed. After watching auction sites for a few months, I bought one unit with a badly broken case, and also a bare chassis with a few missing parts ( Figure 5). I noted color codes on all the transistors and pulled them for testing. Other than the color codes, the germanium transistors had no part numbers, just a Texas Instruments logo on the side made with a rubber stamp ( Figure 6). I have read that the coding was primarily to show junction capacitance, so, the better units could be used in the converter and IF stages, and the higher capacitance transistors in the less critical audio stage. When I tested them, all the transistors showed a huge amount of reverse leakage compared to later transistors. I chose the best transistors and set them aside. I then replaced the bad output transformer. Of the four electrolytic capacitors, three were open and one was shorted. Sony transistor radio schematic series#.Sony transistor radio schematic driver#.Sony transistor radio schematic serial#.Sony transistor radio schematic serial number#.DC Power Sourcesĭirect current (DC) power sources provide electric current that flows in a constant direction. Every functional electronic circuit needs to have a DC or AC power source. Power sources supply electrical energy to a circuit in the form of voltage and current. After this article, I recommend reading How to Analyze Circuits, where we discuss more advanced circuit analysis techniques like Kirchhoff’s Current Law and Kirchhoff’s Voltage Law. You should also be able to get a rough idea of how the circuit works, just by looking at the schematic. It’s not enough to just be able to recognize the components in a schematic. The main goal of this tutorial is to show you the essential schematic components you should know. Each physical component (i.e resistor, capacitor, transistor) has a unique schematic symbol. To start developing your schematic reading abilities, it’s important to memorize the most common schematic symbols. The ability to read electrical schematics is a really useful skill to have.
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