An interesting collection of various vintage glass tube valves. 
Thermionic tube or thermionic valves utilised thermionic emission of electrons from a hot cathode for fundamental electronic functions such as signal amplification and current rectification.
Makes within this collection include Tungsram, Brimar, Marconi, Mazda, Telefunken, Mullard etc.
42 individual valves for use in decorative work and possibly repairs. The valves photographed are what you will receive.
Valve History 
In 1883, Thomas Edison was experimenting with electric lamps. In his early experiments, the glass bulb was becoming dull, and he wondered if this was due to particles being given off by the filament. He fitted a metal plate inside the bulb to attract these particles, and found that if the plate was at a positive potential a current would flow from the filament.
Later Professor Flemming found that current only flowed when the plate was positive, and that the arrangement could be used to rectify an alternating voltage. He patented this in 1904.
When a metal is heated to a sufficiently high temperature in a vacuum, it will give off electrons. These will be attracted to any electrode that is at a more positive potential.
Most metals will melt by the time they are hot enough to emit a significant amount of electrons. Tungsten is an exception, which gives good emission at 2300 to 2500 degrees Centigrade, and melts at 3380 degrees Centigrade. This would glow almost as bright as an electric lamp, which was a characteristic of early Bright Emitter valves. In later valves, the tungsten was coated with an oxide (such as barium or strontium) which gives good emission at around 700 degrees Centigrade.
In most valves, the emitting conductor is a separate component to the heating filament. The emitting conductor is known as the cathode, and is normally in the form of a thin tube. The heater passes inside the cathode and is electrically insulated from it. This is known as an indirectly heated cathode. Some valves have directly heated cathodes, where the heater and cathode are the same component. These were frequently used in battery sets.
This collection is sold untested and includes the plastic box shown in our images.
The valves will be carefully protected for their journey by post.
£80.00 for the set plus £9.00 UK mainland postage = £89.00 delivered to UK zone 1 addresses.
For overseas postage and delivery to UK addresses outside UK zone 1 please enquire.
The collection pictured is the collection you will receive, the other items in our photographs are not included.