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Old 30th Mar 2020, 12:33 pm   #1
FERNSEH
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Default The Ever-Ready experimental transistor TV set.

Now that I've been forced to close the shop during the Corona virus crisis I can get on with many outstanding restoration projects. The Ever-Ready all transistor TV set is one. Got to admit I was a bit reluctant to examine this set having been led to believe that there is some special circuits in the set. Well, it turns out most of the circuits are typical of early sixties transistor TVs such as the Pye TT1 and Ferguson 743T. In fact the IF PCB board in the E-R TV is from the Ferguson 743T. The reason for that is simple, Thorn laboratories did the design and construction of the set for the Ever-Ready company. ER made the special battery for the set, the TV1.
The circuits of the timebases have been traced out, the line oscillator control circuit apart there is nothing particularly special to comment about.
But the power supply arrangements is different and will be examined this week starting with the EHT generator. The attachment shows the internals of the EHT generator unit.
At least we have a brief description of the power supply arrangements. From page 122 of the December 1964 Practical Television magazine.
The Ever-Ready prototype Mk5 405 line transistor TV receiver. Extract from the description of the set.
"A separate blocking free-running oscillator feeding a five stage Cockroft-Walton multiplier provides EHT. A metrosil is employed to regulate EHT and give focus potential.
The particular triumph of the circuit is the stabilised power generator which maintains the battery volt-ampere product substantially constant. This employs three transistors, five diodes and a high ratio transformer with complicated suppression and smoothing."

On a small PCB we find a Mullard OC35 power transistor, an Ediswan XA701 and a Mullard PNP silicon OC703 transistor in the regulator circuit. Also two stud type diodes, a 6.2volt OAZ703 Zener diode and two small diodes, the types of those will be determined after further examination of the board.

DFWB.
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Last edited by FERNSEH; 30th Mar 2020 at 12:46 pm.
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Old 30th Mar 2020, 2:52 pm   #2
kalee20
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Default Re: The Ever-Ready experimental transistor TV set.

With Ever-Ready making the battery, it would not have surprised me if they hadn't just gone direct, and made umpteen small layer cells in series adding up to EHT!

With good insulation, no EHT on-off switching would be necessary. Servicemen would have to watch out, of course...
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Old 30th Mar 2020, 3:10 pm   #3
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Default Re: The Ever-Ready experimental transistor TV set.

The objective of the designers of the Ever-Ready Mark 5 TV receiver was to reduce the power consumption to 3 watts helped by the use of a special 45 degree deflection angle CRT. To give you an idea how modest the deflection power is, the frame output stage employs a single OC200 transistor.

DFWB.
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Old 30th Mar 2020, 4:48 pm   #4
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Default Re: The Ever-Ready experimental transistor TV set.

3W & 40 hours is amazing! I would have expected more like 30W! What screen size is it? Presumably, with 45 degree deflection, the tube is quite long?

I find these early transistor 405 only sets fascinating. I can imagine the designers coming up with ingenious ways of squeezing every last bit of performance out of these strange new devices.

Thanks for posting about this set. A few more pictures would be nice!

All the best
Nick
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Old 30th Mar 2020, 5:53 pm   #5
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Default Re: The Ever-Ready experimental transistor TV set.

Hi Nick,
The CRT is a special Mazda development type V3271. It has a full square flat faceplate, 7" diagonal, P4 phosphor. There is no line output transformer, the 2N1046 line output transistor drives the scanning coils direct. Drive to the PNP transistor is by a broad negative going pulse and the sawtooth drive is generated in the high inductance scan coils, just as it would be in the primary of a line output transformer. The transistor is turned off during the flyback. A Mullard OA5 serves as the damper diode.

Worth noting the Pye TT1 draws less than 2amps from the internal battery pack. The CRT has 6.3V 0.3amp heater.

DFWB.
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Old 30th Mar 2020, 10:05 pm   #6
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Default Re: The Ever-Ready experimental transistor TV set.

Hi David,
I would love to see the complete circuit for the timebases, EHT & power supply if you get to a point of having traced them out!

Cheers
Nick
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Old 31st Mar 2020, 11:47 am   #7
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Default Re: The Ever-Ready experimental transistor TV set.

Hi Nick,
here is the circuit of the timebase panel, in fragmented form.
The synchronising of the line oscillator is implemented a simple comparator circuit employing two transistors. As it is now without any signal input the line oscillator is way off the correct frequency and it hoped that when the sync pulses are present the oscillator will operate at the correct line timebase frequency, 10.125Khz.

DFWB.
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Old 31st Mar 2020, 11:51 am   #8
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Default Re: The Ever-Ready experimental transistor TV set.

The good news is the EHT unit still works. I was bit worried because the set stopped working last Saturday along with a slight smell of overheating somewhere in the set. The OC35 series regulator transistor in the power supply is short circuit between emitter and collector.
The EHT oscillator operates at a frequency of 5Khz, this was confirmed by oscilloscope traces. First with my faithful thirty-six year old Hitachi V650 and later with the new RS Components Proscope. I still prefer to use the older 'scope. That instrument was resident in the shop's workshop and now for the time being it is employed in the isolation workshop.

DFWB.
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Old 31st Mar 2020, 1:05 pm   #9
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Default Re: The Ever-Ready experimental transistor TV set.

Close up picture of the EHT transformer. Note the selenium "stick" rectifier, one of ten, and the BS415 type capacitors employed in the multiplier cascade.
Also worth noting is the use of 4BA nuts as spacers.

DFWB.
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Old 31st Mar 2020, 1:09 pm   #10
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Default Re: The Ever-Ready experimental transistor TV set.

All my (engineering, started at 4) life I have always loved the simple* circuit, they have done an awful lot with but a few components here. It was once said "anyone can do anything, it takes an engineer to do it for a shilling".

*simple as in few bits, not operation.
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Old 31st Mar 2020, 4:26 pm   #11
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Default Re: The Ever-Ready experimental transistor TV set.

Super, David, thanks for circuits also! Completely echo Merlinmaxwell's comments.

Also interesting that they used the silicon OC200 in the frame timebase - I wonder why, most others being germanium?
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Old 31st Mar 2020, 5:37 pm   #12
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Default Re: The Ever-Ready experimental transistor TV set.

Kalee20 wrote: "Also interesting that they used the silicon OC200 in the frame timebase - I wonder why, most others being germanium?"

Hi Kalee, There is a Mullard silicon transistor in the power supply circuit, an OC203.
The OC200 was first introduced in 1960, the developer was Mullard.
Remember reading about the new transistor in the Wireless World.
I'm busy tracing out the circuit of the power supply and will post up a circuit diagram in due course. It's not a simple series regulator. Something much more interesting.
From the Radiomuseum: https://www.radiomuseum.org/tubes/tube_oc200.html

DFWB.
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Old 31st Mar 2020, 9:21 pm   #13
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Default Re: The Ever-Ready experimental transistor TV set.

Here's my interpretation of the circuit of the power supply. It's unlike any other transistor TV set that was manufactured in the early sixties.
It's an adventurous design for 1963.
Now I have to find out in the circuit where the power from the battery is injected.

DFWB.
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Old 31st Mar 2020, 10:18 pm   #14
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Default Re: The Ever-Ready experimental transistor TV set.

Something wrong there David, the emitter of the OC35 goes to a 10k resistor (plus a capacitor), nowhere else to draw any current from!

Fascinating seeing this all being revealed, though - it must have taken a lot of time to be developed!
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Old 31st Mar 2020, 10:31 pm   #15
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Default Re: The Ever-Ready experimental transistor TV set.

We'll have to find out what the oscillator frequency is when it's up and running.
I'll re-check the circuit layout again, it just doesn't look right somehow.
The circuit is designed to supply a steady 10volt supply to the receiver irrespective of battery voltage. It's potentially a much better power supply system compared with the simple series loss element type of regulator circuit.

DFWB.
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Old 31st Mar 2020, 11:50 pm   #16
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Default Re: The Ever-Ready experimental transistor TV set.

The power supply circuit is beginning to make sense. The positive terminal of the battery is supplied direct to the emitter of the OC23 transistor and the negative terminal goes direct to the chassis, which is of the positive side of the regulated 10volt supply.

DFWB.
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Old 2nd Apr 2020, 3:12 pm   #17
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Default Re: The Ever-Ready experimental transistor TV set.

I've redrawn the power supply circuit and I'm sure I've got it right now.
The collectors of the PNP regulation transistors XA703 and OC203 are connected to the primary circuits ground line which goes to the battery negative. In my earlier power supply circuits the collectors and emitters of the transistors were transposed.
The restoration is held up until a replacement OC35 is found. All the 5000microfarad smoothing capacitors will have to be replaced.

DFWB.
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Old 2nd Apr 2020, 4:42 pm   #18
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Default Re: The Ever-Ready experimental transistor TV set.

What is the battery voltage, I can't find it in this thread (that's not to say it isn't there).
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Old 2nd Apr 2020, 5:15 pm   #19
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Default Re: The Ever-Ready experimental transistor TV set.

Ever-Ready type TV1, 12volts.

DFWB.
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Old 2nd Apr 2020, 8:29 pm   #20
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Default Re: The Ever-Ready experimental transistor TV set.

Hi David, OC 28, 29, 35 or 36 could well all be suitable

Ed
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