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Low Voltage Valve/Tube Buffers/Hybrids/Amps

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Graham Slee View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 27 Jan 2016 at 1:24pm
My Junior's teacher once brought in some batteries for us to experiment with. One was a 90V HT battery!!!

I accidentally shorted it with some thin bare wire which instantly glowed and burnt in two. It also discharged it...  Luckily I avoided the cane.
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BAK View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BAK Quote  Post ReplyReply Direct Link To This Post Posted: 27 Jan 2016 at 3:17pm
Originally posted by Graham Slee Graham Slee wrote:

My Junior's teacher once brought in some batteries for us to experiment with. One was a 90V HT battery!!


Have I got my A B C s mixed up?

Isn't that where we got "B+" to mean the high voltage power supply?
 ... 90 volt HT battery was called the "B" battery, as I recall.

An "A" cell was the grid bias battery?

A "C" cell was the filament ? 


Edited by BAK - 27 Jan 2016 at 3:32pm
Bruce
AT-14SA, Pickering XV-15/625, Technics SL-1600MK2, Reflex M, Lautus, Technics SH-8066, Dynaco ST120a, Eminence Beta 8A in custom cabs;; Using Majestic DAC
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DaveG Quote  Post ReplyReply Direct Link To This Post Posted: 27 Jan 2016 at 7:01pm
Originally posted by Graham Slee Graham Slee wrote:

..  Luckily I avoided the cane.


Ha! if it happened these days it's more likely Injurylawyersrus would be encouraging the parents to sue the skool for scaring little Graham Tongue
Dave

Michell Gorbe + HR PSU -> Cadenza Bronze -> SME V -> Elevator -> Accession -> Proprius -> B&W CM6 s2 | Cusat 50 & Spatia cables ->
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 27 Jan 2016 at 7:55pm
Indeed! If we could just get all the injury lawyers to visit each other's offices, fall over and sue each other... perpetual inflation.
Jon

Open mind and ears, whilst owning GSP Genera, Accession, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 27 Jan 2016 at 11:53pm
Originally posted by BAK BAK wrote:

Originally posted by Graham Slee Graham Slee wrote:

My Junior's teacher once brought in some batteries for us to experiment with. One was a 90V HT battery!!


Have I got my A B C s mixed up?

Isn't that where we got "B+" to mean the high voltage power supply?
 ... 90 volt HT battery was called the "B" battery, as I recall.

An "A" cell was the grid bias battery?

A "C" cell was the filament ? 


Sounds right to me.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jan 2016 at 12:11am
US Patent 5450034 looks interesting and reached its 20 years last September, so it will be turning up in all sorts of valve hybrids soon (if not already).

http://www.google.co.uk/patents/US5450034

It's called a Reflected Plate Amplifier and is very similar to the two transistor stage used in many a transistor preamp circuit.

It suggests the use of one half of a twin triode, but the other half couldn't be used for the second channel (because of crosstalk) and would be wasted.

It gave me the idea to try making a differential input stage which would use both halves and traditional negative feedback could be applied in a more predictable manner (I do so hate wasting time and components on "what if's").

At least the invention could make use of the same plate voltage used in a class-a 90V HT supply circuit using just 45 volts for its supply, as there is no conventional plate (anode) load. Therefore the valve's designed characteristics would be met.

I will try and draw up the basic circuit and present it here, and if it succeeds you never know, the stage could be offered as a kit...

We'll see.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jan 2016 at 2:05am
Just an idea...


It may work Clown



Edited by Graham Slee - 28 Jan 2016 at 2:06am
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