Evolution of the energy recovery diode. - UK Vintage Radio Repair and Restoration Discussion Forum

Argus25 · 17th Nov 2016, 2:24 pm

I noticed that although the energy recovery diode (or damper diode) in horizontal output stages is referred to in many television textbooks, there didn't appear to be an overview article showing how the notion of it evolved and how we ended up with the circuit configuration that basically became world standard after RCA released their 621TS TV set in 1946.

It appears Blumlein thought up the idea before WWII, because RCA referred to his patent in their early research literature, but the Americans were first to commercialize the concept on a large scale. So I wrote an article about it decade ago here:

http://worldphaco.com/uploads/TELEVI...R_DIODE_OR.pdf

I thought I would open this topic/thread for discussion, if there are others with a knowledge of very early TV sets using the energy recovery technique so as to get a handle on the true chain of events around the 1936 to 1946 period when this remarkable advancement in magnetic horizontal scanning technology took hold.

What is the earliest UK made TV set that incorporated this technique ?

Brigham · 17th Nov 2016, 2:54 pm

Is this also known as the 'efficiency diode'?

toshiba tony · 17th Nov 2016, 3:03 pm

In the olden days it was also called the "boost diode" PY81/88 for mono and PY500 for colour. In fact the derived supply was called the boost line. And the .47 caps that used to go s\c was referred to as the boost cap, ah, memories.

Welsh Anorak · 17th Nov 2016, 3:37 pm

In fact it was originally known as the 'booster diode' - remember Bleep and Booster on Blue Peter? We all remember the blue and white boost cap!
Interestingly, the very early GEC 2040 series single-standard hybrid used a conventional PL509 line output valve with a solid state boost diode! I only saw a couple of these - the design reverted to the good old PY500A pretty sharpish. Anyone else remember them?
Glyn

FERNSEH · 17th Nov 2016, 4:18 pm

Damper diode, reclaim diode and booster diode are all terms used over time.
The damper diode was the attempt to improve the efficiency of the line output stage. You have to go back the early 1930s and the beginnings of magnetic deflection in TV receivers. It was known that at the end of the scan the rapid flyback time initiates an oscillation in the scan coils. A damping resistor across the scan coils can reduce the oscillation but this is wasteful and saps up too much energy. A better solution is to make the damping circuit more frequency selective so a capacitor was inserted in series with the resistor, the degree of damping can be adjusted to serve as a linearity control.
Even better still is use a diode valve to conduct on the first cycle of the "ring" . Valuable energy will stored in a capacitor connected in series with the diode and this can be used to supply extra volts to the line output valve. Take a look at the circuit of the 1949 Murphy V120C to see how it was done.
In fact certain pre-war Baird TVs employed a damper diode. The line output valve was a power triode and the diode was connected across the triode in a reverse manner, that is the diode cathode connected to the anode of the triode and the anode to ground. An HT rectifier diode like the UR1C was used because of the high currents in the damping circuit. See fig 5 in the attachment on post #1
The attachment in the first post shows the evolution of the efficiency diode.
The 1949 HMV 1807 has a damper diode, an U31 which is a radio HT rectifier diode used in AC/DC mains sets.
DFWB.

toshiba tony · 17th Nov 2016, 4:22 pm

Yes, gawd that takes me back, a short run idea, almost as crazy as the PL802\t, never seemed quite as good a the thermionic one, and, off topic what about the Pye 697 solid state cda panel.

beery · 17th Nov 2016, 4:36 pm

Hi All,

The earliest example of a damper diode (though not used as a boost diode) I have found is in the circuit of the EMI monitors that were used as AP. They must have been designed in about 1935.

See the link to the circuit (see page 22):-
http://www.earlytelevision.org/pdf/a...ok_part-10.pdf

Cheers
Andy

FERNSEH · 17th Nov 2016, 4:43 pm

Hi Andy,
You beat me to it, I was going to mention the AP picture monitor as well.

DFWB.

G6Tanuki · 17th Nov 2016, 4:45 pm

Ler us not forget those TVs that abused the Mazda U801 quadruple-diode as a flyback-rectifier as well as the main HT rectifier.

I guess that to someone the idea of combining the two functions in one 'bottle' seemed to have been a good idea at the time. . .

Heatercathodeshort · 17th Nov 2016, 4:50 pm

The 'Wireless World' magnetic television receiver [1939] used a URIC as a damper diode. J.

FERNSEH · 17th Nov 2016, 4:56 pm

WW magnetic receiver used parts supplied by Baird Television. BTL advertised scanning components for sale to home constructors.

DFWB.

kalee20 · 17th Nov 2016, 7:07 pm

Quote:

Originally Posted by Argus25

...I wrote an article about it decade ago here:

http://worldphaco.com/uploads/TELEVI...R_DIODE_OR.pdf

Good article!

17th Nov 2016, 2:54 pm	#2
Brigham Octode Join Date: Mar 2006 Location: Co. Durham, UK. Posts: 1,117	Re: Evolution of the energy recovery diode. Is this also known as the 'efficiency diode'?

17th Nov 2016, 3:03 pm	#3
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Evolution of the energy recovery diode. In the olden days it was also called the "boost diode" PY81/88 for mono and PY500 for colour. In fact the derived supply was called the boost line. And the .47 caps that used to go s\c was referred to as the boost cap, ah, memories.

17th Nov 2016, 3:37 pm	#4
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,921	Re: Evolution of the energy recovery diode. In fact it was originally known as the 'booster diode' - remember Bleep and Booster on Blue Peter? We all remember the blue and white boost cap! Interestingly, the very early GEC 2040 series single-standard hybrid used a conventional PL509 line output valve with a solid state boost diode! I only saw a couple of these - the design reverted to the good old PY500A pretty sharpish. Anyone else remember them? Glyn

17th Nov 2016, 4:18 pm	#5
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Evolution of the energy recovery diode. Damper diode, reclaim diode and booster diode are all terms used over time. The damper diode was the attempt to improve the efficiency of the line output stage. You have to go back the early 1930s and the beginnings of magnetic deflection in TV receivers. It was known that at the end of the scan the rapid flyback time initiates an oscillation in the scan coils. A damping resistor across the scan coils can reduce the oscillation but this is wasteful and saps up too much energy. A better solution is to make the damping circuit more frequency selective so a capacitor was inserted in series with the resistor, the degree of damping can be adjusted to serve as a linearity control. Even better still is use a diode valve to conduct on the first cycle of the "ring" . Valuable energy will stored in a capacitor connected in series with the diode and this can be used to supply extra volts to the line output valve. Take a look at the circuit of the 1949 Murphy V120C to see how it was done. In fact certain pre-war Baird TVs employed a damper diode. The line output valve was a power triode and the diode was connected across the triode in a reverse manner, that is the diode cathode connected to the anode of the triode and the anode to ground. An HT rectifier diode like the UR1C was used because of the high currents in the damping circuit. See fig 5 in the attachment on post #1 The attachment in the first post shows the evolution of the efficiency diode. The 1949 HMV 1807 has a damper diode, an U31 which is a radio HT rectifier diode used in AC/DC mains sets. DFWB. Last edited by FERNSEH; 17th Nov 2016 at 4:29 pm.

17th Nov 2016, 4:22 pm	#6
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Evolution of the energy recovery diode. Yes, gawd that takes me back, a short run idea, almost as crazy as the PL802\t, never seemed quite as good a the thermionic one, and, off topic what about the Pye 697 solid state cda panel.

17th Nov 2016, 2:24 pm	#1
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Evolution of the energy recovery diode. I noticed that although the energy recovery diode (or damper diode) in horizontal output stages is referred to in many television textbooks, there didn't appear to be an overview article showing how the notion of it evolved and how we ended up with the circuit configuration that basically became world standard after RCA released their 621TS TV set in 1946. It appears Blumlein thought up the idea before WWII, because RCA referred to his patent in their early research literature, but the Americans were first to commercialize the concept on a large scale. So I wrote an article about it decade ago here: http://worldphaco.com/uploads/TELEVI...R_DIODE_OR.pdf I thought I would open this topic/thread for discussion, if there are others with a knowledge of very early TV sets using the energy recovery technique so as to get a handle on the true chain of events around the 1936 to 1946 period when this remarkable advancement in magnetic horizontal scanning technology took hold. What is the earliest UK made TV set that incorporated this technique ?

17th Nov 2016, 4:36 pm	#7
beery Heptode Join Date: Jun 2006 Location: Ware, Hertfordshire, UK. Posts: 988	Re: Evolution of the energy recovery diode. Hi All, The earliest example of a damper diode (though not used as a boost diode) I have found is in the circuit of the EMI monitors that were used as AP. They must have been designed in about 1935. See the link to the circuit (see page 22):- http://www.earlytelevision.org/pdf/a...ok_part-10.pdf Cheers Andy __________________ www.youtube.com/user/andyvalve100

17th Nov 2016, 4:43 pm	#8
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Evolution of the energy recovery diode. Hi Andy, You beat me to it, I was going to mention the AP picture monitor as well. DFWB.

17th Nov 2016, 4:45 pm	#9
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Evolution of the energy recovery diode. Ler us not forget those TVs that abused the Mazda U801 quadruple-diode as a flyback-rectifier as well as the main HT rectifier. I guess that to someone the idea of combining the two functions in one 'bottle' seemed to have been a good idea at the time. . .

17th Nov 2016, 4:50 pm	#10
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Evolution of the energy recovery diode. The 'Wireless World' magnetic television receiver [1939] used a URIC as a damper diode. J.

17th Nov 2016, 4:56 pm	#11
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Evolution of the energy recovery diode. WW magnetic receiver used parts supplied by Baird Television. BTL advertised scanning components for sale to home constructors. DFWB.