Ford? Chevy? Oldsmobile? Who started offering radios as a standard feature in cars? Which models?
My Uncle always claimed that he was in the car driving when they “Announced the sneak attack by the Japs on Pearl Harbor” He joined the Navy two days later. So, that places car radios in cars by at least 1941.
They would have been AM of course. I serviced several from the late 1940’s for my dads antique car club. Even those were big monsters with tubes and they used a mechanical vibrator to chop up the DC voltage into a rough square wave. It then was amplified through a transformer, had a dual rectifier tube, and filtered with capacitors. I had to replace several faulty vibrators and the old wax and electrolytic capacitors.
1930’s tubes were bigger than what was used in the the late 40’s and 50’s. Making a 1930’s car radio that could fit in the dash would be tricky.
From the Motorola company history: “1930: Company founder Paul V. Galvin learned that some radio shops were installing sets in cars. Inspired, he challenged his employees to design an inexpensive car radio that could be installed in most vehicles. With the hard work of an enthusiastic team, Galvin was able to demonstrate a working model of the radio at the June 1930 Radio Manufacturers Association convention in Atlantic City, New Jersey. Afterward he was able to bring home enough orders to keep the company afloat.”
The first car radio was built by Bill Lear, who sold his radio coil manufacturing business to Galvin in exchange for one-third share in Galvin’s company. The two men came up with the name “Motorola” together while on a road trip. Lear is probably most famous for founding LearJet and manufacturing the first small private business-class jet. He developed radio direction finders, autopilots, and the first fully automatic aircraft landing system. Lear also developed the 8-track stereo cartridge, a refinement of earlier 4-track tape cartridges as a convenient means of playing music aboard his jets.
Oh, I hadn’t thought about this. Since internally radios only need DC, I was puzzled why a square wave (to produce AC) was needed. Old battery radios had “A”, “B” and “C” voltages (hence the origin of the battery names).
The output amplifier tube of a classic AC radio was typically 35-50V on the filament. With higher voltages (like 250V) here and there.
But DC radios operated on “battery” voltage levels. So I’m guessing that this old radios were more or less AC models that got adapted for mobile use rather than intrinsically designed DC models.
Tuuuubes… prr Ahem, pardon me. I have a fascination with tubes and tube radio equipment; even futzed around a bit with DIY restoration, but moved to NYC (and away from adequate workshop space) before I could get very far into it.
Anyway, as I recall, one of the big problems w/ car tube radios was the fragility of hot tubes–needed a way to insulate them from the road vibrations. Of course, once you can do that, the obvious next step is to install an in-dash record player…
The car radios I worked on were nearly identical to any standard 5 tube radio that was sold for household use. The biggest difference was the inverter power supply that took the car battery voltage and converted it to AC. The rest of the power supply was a standard dual rectifier just like household radios. Car radios did have a lot more shielding. Those metal cases made them heavy.
On my workbench the DC vibrator made an annoying buzz. But, I guess the road noise in the car drowned it out. I never noticed the buzz after the radio was installed in the car. These days, a lot of restorers replace bad vibrators with a solid state component. Much more reliable.
This link has an old 1953 car radio broke down. Brings back memories. It’s been about 25 years since I restored one of these.
A vibrator was a kluge, but high DC voltage was the only way to get enough power to drive a speaker. Much later in the later 1950s when transistors were available but expensive there was a hybrid design that did away with the vibrator and used special tubes that could run on 12 volts for the input stages, and a transistor or two to drive the speaker.
Larger power applications like mobile radio transmitters used dynamotors, or a AC generator attached to a DC motor. Supposedly the origination of 10 codes is because police tended to forget it needed time to spin up and they would talk before the transmitter was ready.