Circuits

Fifty years of Battery Radio: 1920s to 1970s

Originally all Radios used batteries for two main reason, one that few people had mains electricity and secondly the valves (tubes) used direct filaments, so any mains hum would be amplified. From the late 1920s valves with insulated heaters and a separate cathode became available for mains radio. But up to the 1950s “table radios” (USA called them Farm Radios) were available with battery operation for people without mains Electricity, mostly using Lead Acid (rechargeable accumulator, charged maybe once a week at the cycle shop or garage).

From the late 1920s fully self contained battery sets made to be portable or at least easily transportable were developed.

Eras of devices for Radio

• Bright Emitters, pure tungsten 1905 to early 1920s
• Quite Bright Thoriated Tungsten, early 1920s
• Dull Emitters, Oxide coated with gradual improvements Mid 1920s to 1945
• Mains Radio valves/Tubes from late 1920s
• All Dry types 1.4V 1938, “50mA” types
• Miniature All dry B7G 1939/1940
• Telefunken Metal case 1.2V types 1940
• Subminiature versions 1940s & 1950s
• Transistor from 1948 (Mid 1950s in radio, not widespread till 1958)
• Low current “25mA” type early 1950s
• Russian Rod Pentodes, 1950s to 1970s (Military only)
• Nuvistors 1950s (very few Radio or TV, mains only). Miniature metal case valve/Tube.
• Integrated circuits in Domestic Radio from 1968

More to come

Some famous or generic circuits to Download

TRF using single Triode.

TRF using Triode RF, Anode Bend Triode detector and Triode audio amp.

Neutrodyne version of  TRF

TRF using Screen Grid Valve ( RF Tetrode Tube) for RF and one to three triodes

TRF “SG Det Pen”.  Screen Grid RF Amp, Anode Bend Triode detector and Pentode audio amp.

Early Superhets with separate Mixer and Oscillator.

AM Superhet using a Pentode as Mixer/Oscillator.

The All American Five. A five tube superhet radio. Actually really the only “American” aspects are the typical use of  Heptode/Pentagrid converter and 115V nominal supply.

RCA 1940 “All Dry Portable” / “Personal Radio”. Basis for almost all 1950s Tube/Valve battery portable Radio sets.

Short Superhet using combined detector & output Pentode with no Audio Preamp.

Seldom used Superhet with no  separate IF amp.

Single tube VHF tuners mains & Battery (EF80, ECC85, ECF82, DC90, DF97)

Grundig Single Pentode Stereo Multiplex decoder.

Russian Rod Tube transmitter used in Sputnik

Mullard Audio Amplfier

Williamson HiFi Audio amplifier

Guitar / Stage amplifier

Magic Eye used in a Test Bridge

Typical Signal generator using Triode RF Oscillator and Triode AF Oscillator / Modulator

TV Line Output. Flyback EHT supply

Valve Voltmeter VVM, Electrometer, Tube based Meter

Hearing Aid.

All valve car radio (tube auto radio)

Hybrid car radio. Both Transistor for 90V HT only and 12.6V HT and Transistor audio output.

Pocket Tube Radio using 1V6 sub-miniature converter

WWII Covert Receivers and transmitters

Electrostatic Microphone / Condenser Microphone.

 Projects to build today (2014)

(Using common valves, cheap Russian Tubes and Rod Pentodes)

Hi Fi Amplifier

Guitar Amplifier using common tubes

Mains superhet radio, optional VHF-FM, optional Push Pull, optional Stereo decoder, magic eyes.

Battery Superhet radio. Versions with VHF-FM, Push Pull, stereo and Magic Eye.

Battery TRF: 1920s style and 1930s style (using Russian Rod Pentodes)

Covert replica battery radio sets based on WWII circuits

Battery Dual Conversion Receiver (optional transmitter)

Mains Dual Conversion Receiver (optional transmitter)

Tube Hybrid Car Radio with LW, MW, SW and VHF-FM stereo (transistor HT rather than vibrator).

Capacitor Leakage tester.

100M Ohm input voltmeter.

HT Battery Eliminator  from LT battery  (45 to 145V HT voltages, 1.5V to 9V input)

HT Battery Eliminator  from mains (45 to 145V HT voltages, 115 or 230V AC in nominal)

LT Battery Eliminator  from mains (Replace 1.5, 2, 4,  6, 7.5 or 9V batteries, 115 or 230V AC in nominal)