Before transistors were available,
what tubes/valves were used for driving incandescent lamps?

Question

In the early days of computers, there were of course no transistors.

There was at least one type of tube that was specifically designed to drive regular incandescent lamps.

I suspect there were actually several types available.

The one I really want to know about was used in a homemade color organ that was either a one-off or a project built from a magazine article.

Many online searches have failed to turn up the type of which I personally saw and handled three samples, so I Will Not accept responses saying that there was no such thing.
It was, in fact, listed in one tube manual
that later disappeared --- and it was the Only one found with the listing.

I think it was a 5000 series or 7000 series 4-digit type number.

daniel g · Answer

Incandescent lamps never were directly controlled by tubes to my know, and I cut my teeth on tubes.
Relays were the norm, but today, power mosfets work well.
Semiconductors and transistors were brand new technology when I started in electronics.
About your color organ, you might search older popular electronic magazines, but consider, even a 6L6 can only handle a 50 watt load in such application. Not many tubes functioned at 150 volts and capable of much current at all.

異域秦後人 · Answer

In the old day like before 1950, complex relays set up system  was the parts to do simple logic circuit to drive  small power lamp as the logic indicator. But relay is too slow to be used to build high speed electrical calculator ( computer was not yet invent ). Electronic tube was used to take over relay logic circuit because tube is super fast compare to mechanical relay, common used is triode like 12AX7.

Before transistors were available, what tubes/valves were used for driving incandescent lamps?

2 Answers