Share:
Notifications
Clear all

1963 Ever-Ready experimental all-transistor TV set.  

Page 4 / 5
 
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered
Posted by: @till

Noteworthy is the very low power consumption which varies between 0.25 to 0.3amp.

That is really low - I'd expect the tube's heater to draw that much alone!

ReplyQuote
Posted : 18/04/2020 9:03 pm
Till Eulenspiegel
(@till)
Famed V-Ratter Registered

The CRT heater voltage is 6.3 but the current is unknown.  I'll measure the current at the first opportunity.

The gun assembly is something special. The tube neck diameter is the standard 28.5 mm as used on almost all 110 degree CRTs with the B8H base. There is no first anode as such so there are no connections to pin 3. There is a note on an upper chassis member is informing us that the focus is bad. It was always assumed that the slider control on the EHT metrosil is the first anode voltage adjustment, in fact it is the focus control and is connected to pin 4 on the CRT base which is the connection to the focus electrode on most 110 degree tubes. The slider control was readjusted and really excellent focus was achieved, it's so good that the line structure on the 7" diagonal CRT can be clearly seen

ER TV Spec CRT no focus
ER TV Spec CRT
ER TV Spec CRT 2
ReplyQuote
Posted : 19/04/2020 12:56 am
Nuvistor liked
Lloyd
(@lloyd)
Noble V-Ratter Registered

Great to see you got it working! It’s really amazing that it uses so little current, I don’t think I’ve ever come across another tv that uses so little.

 Regards 

Lloyd 

ReplyQuote
Posted : 19/04/2020 8:53 am
peterscott
(@peterscott)
Prominent V-Ratter Registered

@till

Really good result! How effective is the regulation when you vary the supply voltage? Does the picture change much?

Peter

www.nostalgiatech.co.uk

ReplyQuote
Posted : 19/04/2020 9:07 am
Till Eulenspiegel
(@till)
Famed V-Ratter Registered

Hi Peter, the regulation is pretty good. It's safe to say that there is no noticeable changes to the picture geometry between supply voltages 9 to 12 volts. In fact the set is still usable on 6.5 volts although the picture height and width is much reduced. With the power supplier set to 12.5 volts the CRT heater voltage is 6.34 and the supply to the receiver and timebases circuits is 12.19V.                                                                                                    

With 10volts the CRT heater voltage is 6.28 and 12.08V for the other circuits. Reduce the supply voltage to 8 and the CRT heater voltage falls to 6.08V. 11.72 for the other circuits. Slight adjustment of the frame line controls required otherwise perfect pictures. Even operating with 7volts the set is displaying a good picture but the picture height and width is reduced. CRT volts 5.74. Receiver and timebases 11.11V On 6.2 volts the set still works in a fashion but picture stability is bad. CRT 5.24V and 10.16 for the other circuits.

Of course things might be much different when the receiver supplied from a battery. With use the battery voltage falls and the internal resistance goes up and this is where there will be problems. When the supply voltage is reduced the current demand goes up to maintain the V-A product. A battery pack similar to the TV1 or HP1 can be made up. Even a pair of Ever-Ready 996 lantern batteries could be employed, but before that the vision AGC and frame sync faults must be put right.

Till Eulenspiegel

ReplyQuote
Posted : 20/04/2020 1:40 am
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered

@till

If memory serves me right, the Roberts R707 uses a pair of 996 batteries to power it. Would they fit in the set itself? Certainly a sealed lead-acid or ten NiMH cells could be used to make an externally rechargeable option.

ReplyQuote
Posted : 20/04/2020 10:04 am
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered

Just reading back through this thread, I note the CRT had a Mazda 'V' code, used to denote prototype or special valves. Looking at it further, it makes me wonder if that CRT didn't become a type used in television camera viewfinders; it has attributes that would make it suitable.

ReplyQuote
Posted : 20/04/2020 10:20 am
turretslug
(@turretslug)
Reputable V-Ratter Registered

 

That is a very impressive supply range performance and a credit to the design.

It's a shame that a few potential (yeah OK, haha....) standard 12V lead-acid gel "brick" candidates are outsize in one or other dimension- the 5Ah size too deep at 70mm, the 3 and 7Ah too long. Maybe a couple of appropriate 6V packs offers a suitable juggling of position to fit. Quite often, you see gel brick batteries piled up at recycling centres, sometimes I've stealthily acquired the odd sample, sometimes they're even usable! I had wondered if a Gates Cyclon pack could be made up to suit, but these are liquid electrolyte cells, so there's the potential of acid vapour damage to this nice and rather rare piece of history, even if they are nominally sealed. Maybe NiMH cells in a ten-cell holder are a better option.

One significant thing to be wary of with things like this that have clever PSUs designed to wring the maximum out of expensive primary batteries is that they can end up running rechargeables harmfully low before degradation of equipment performance is noticed, especially if done repeatedly and not charged pronto.

ReplyQuote
Posted : 20/04/2020 4:49 pm
Till Eulenspiegel
(@till)
Famed V-Ratter Registered
Posted by: @cathovisor

Just reading back through this thread, I note the CRT had a Mazda 'V' code, used to denote prototype or special valves. Looking at it further, it makes me wonder if that CRT didn't become a type used in television camera viewfinders; it has attributes that would make it suitable.

Hi Mike, the viewable screen area is 12 X 9cm but perhaps the screen to base measurement of 29.5cm would preclude it's use as a view finder CRT?

Today, I tried another 2G302 transistor in the frame oscillator and although there was a slight improvement, the frequency settled down to 50Hz after 30 seconds or so, that's still not acceptable. In order to solve the problem a silicon pnp OC200 transistor is now being used.  The Pye TT1 employs an OC72 for the frame oscillator. The Perdio Portorama Mark 2 uses an OC81.

Till Eulenspiegel.

ReplyQuote
Posted : 20/04/2020 6:35 pm
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered

You'd be surprised, David - the feature here being the narrow deflection angle (less correction) and it would seem, the small spot size. Even the colour cameras of the 70s and 80s had physically quite big viewfinders. Does the tube have a flat face to it, by the way?

ReplyQuote
Posted : 20/04/2020 6:58 pm
Till Eulenspiegel
(@till)
Famed V-Ratter Registered

Hi Mike, the CRT faceplate is truly flat. Small spot size so good for 625.

ReplyQuote
Posted : 20/04/2020 7:32 pm
Till Eulenspiegel
(@till)
Famed V-Ratter Registered

Here's the set operating from eight ordinary AA dry cells, in fact the set will work with only five cells.

It is my intention to make up a proper battery pack for the set. After all, that was the intention of the designers to make a truly portable TV set. Pity we don't have any 405 line VHF transmitters any more.

Till Eulenspiegel.

ER TV 8 AA cells 2
ER TV 8 AA cells 1
ReplyQuote
Posted : 31/05/2020 11:50 pm
Katie Bush, ntscuser, Doz and 3 people liked
Jac Janssen
(@jac-janssen)
Trusted V-Ratter Registered

@till

Very impressive performance David!

Jac

ReplyQuote
Posted : 01/06/2020 8:06 am
Doz
 Doz
(@doz)
Noble V-Ratter Registered

Impressive stuff! 

ReplyQuote
Posted : 01/06/2020 3:30 pm
Katie Bush
(@katie-bush)
Famed V-Ratter Moderator

And that's working off "AA" cells? That's pretty damned impressive! The set can't be drawing much current at all? You could probably run that set from two, or three, PP9s in parallel? I'd guess though, that the roll off in battery voltage wouldn't give a very long run-time on anything below the manufacturer's specified battery.

ReplyQuote
Posted : 01/06/2020 9:26 pm
Till Eulenspiegel
(@till)
Famed V-Ratter Registered

Hi Marion, the set draws about 0.3amp irrespective of the supply voltage which is in the range of 8 to 12 volts. After twenty minutes use the terminal voltage of the eight AA cells fell to eight volts, the set continued to work still displaying a bright picture.  Still usable on 7volts.

Forum member "Colourmaster" has suggested a motorbike battery to power the set.

On switch-on the picture would roll because the oscillator frequency was above 50Hz. It would take several minutes to display a fully locked picture.   To effect a cure the 1microfarad ramp forming capacitor has been replaced and an AC126 replaces the 2G302 frame oscillator transistor. Because it had gone high value the 100Kohm resistor in series with the frame hold control was replaced some time ago. A 330Kohm resistor is now in parallel with the 100K resistor to improve the range of the frame hold control.

Till Eulenspiegel.  

ER TV FTB 1u0
ER TV FTB Osc
ReplyQuote
Posted : 02/06/2020 11:37 am
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered

@till

Funnily enough Till, just before 'lockdown' my local Halfords was having a clearance on small motorbike batteries! That aside, I'd say it was a perfect application for a sealed lead-acid battery: the Yuasa/Yucel being perfect for the job and you could easily fit one inside the set - it would also be significantly cheaper than a pack of ten NiMH "D" cells (or HP2s in old money).

ReplyQuote
Posted : 02/06/2020 12:03 pm
Katie Bush
(@katie-bush)
Famed V-Ratter Moderator

Following on from Mike's suggestion, I'd also think that a Yuasa, or other brand, NP7-12 (12Volts 7Amp hour) 'non spill-able' AGM battery (bait boat battery) would be ideal. Plus, you can walk into just about any self respecting fishing tackle shop, and come back out a battery right then and there.

ReplyQuote
Posted : 02/06/2020 9:53 pm
Doz
 Doz
(@doz)
Noble V-Ratter Registered

What about a LifePo4? Large capacity, tiny, safe as houses and light. I have one in my Mini... it weighs 1KG! 

Damned expensive mind.

ReplyQuote
Posted : 03/06/2020 11:10 am
Till Eulenspiegel
(@till)
Famed V-Ratter Registered

Hi Doz,  the battery compartment is 130 x 133 x 63mm so anything smaller than this can be fitted.

Meanwhile, the battery made up from eight AA cells is now down to 8.16volts and the set continues to work. The power supply is delivering just under 12 volts. Set can operate down to seven volts.

I'm thinking it might be possible to design a similar converter power supply unit for the Pye TT1.  Requirement is 10volts @ 2.5amps.  The TT1 has already very high value supply filter capacitors, two of 10,000microfarads. 

Till Euelenspiegel.

ReplyQuote
Posted : 04/06/2020 8:03 pm
Page 4 / 5