First Television to use ICs

[Hybrid tellies]

Originally Posted by Jonster

The later Decca 'Bradford' 30 series colour hybrids had a colour decoder with ICs and transistors, while retaining valved timebases. The earlier 10 series had an all transistor decoder if I remember. The ITT CVC5/7/9 were similar.

The Decca Bradford 10 and the Decca 625 line single standard back and white chassis, both circa 1971, used a Motorola MC1351 IC for the 6MHz intercarrier sound and FM demodulation which fed a PCL82 valve amp/output valve.
The earliest TV's I remember using an IC was probably the early RBM A823, from 1969, which used IC's for the 6Mhz sound intercarrier sound and one in the decoder.

[turretslug]

I suppose that it depends on the definition of "IC"- but if it's the accustomed idea of a small planar silicon beastie with lots of transistors in a compact package, then perhaps the ease of achieving consistent performance at TV IF and similar frequencies was an appealing USP, also making it easier for complex multi-stage broadband near-DC to 6MHz or so circuitry for video processing.

The TAA550-type devices are temperature-compensated and would be far better in this respect than lousy higher-voltage Zeners- I've wondered about using them as HT supply error amp references in place of the neons often found.

[FERNSEH]

Originally Posted by toshiba tony

I get confused these days but strictly speaking varicap tuners used an ic for the 33v line. I know a zener was often used but on the early continental sets an IC was used. Even on the circuit diagrams it was referred to as an IC unless it was a zener in disguise.

The TAA500 is essentially a temperature compensated Zener diode.
From the Radiomuseum. https://www.radiomuseum.org/tubes/tube_taa550.html

DFWB.

[Nuvistor]

Originally Posted by G6Tanuki

There again, when ICs did make it into the audio-stages of TVs they were not always spectacularly successful - anyone remember the 1970s Texas Instruments SN76001-style "Hedgehog" chips that had a nasty tendency to burn out if you listened to Top of the Pops too loud?

Yes.

[FERNSEH]

From the Silicon Engine website: 1960 First Planar Integrated Circuit is Fabricated

https://www.computerhistory.org/sili...is-fabricated/

DFWB.

[turretslug]

Originally Posted by toshiba tony

I get confused these days but strictly speaking varicap tuners used an ic for the 33v line. I know a zener was often used but on the early continental sets an IC was used. Even on the circuit diagrams it was referred to as an IC unless it was a zener in disguise.

Perhaps the temperature-compensated TAA550 had been a genuine necessity in earlier sets with straightforward discrete IF/demodulator set-ups but once signal processing ICs appeared with an inherent AFC function that could drive a tuning line, then bean-counters might have spotted that tuning supply volts became less critical and a drifty 33V plain Zener was adequate. Not nice in a purist sense, but it might have saved a few farthings per set!

[Maarten]

Originally Posted by FERNSEH

The TAA550 is essentially a temperature compensated Zener diode.
From the Radiomuseum. https://www.radiomuseum.org/tubes/tube_taa550.html

From the application viewpoint, it is. Inside are several transistors and resistors on a single chip so it's a proper IC. I've never seen a real zener used in that position but when cutting costs, every fraction of a cent counted so it sounds plausible.

[ms660]

Yes, it was called an IC when I was in the trade, transistors etc inside:

https://datasheetspdf.com/pdf-file/769628/ETC/TAA550/1

From the SGS/ATES 1975/76 data book.

Lawrence.

[toshiba tony]

Yes G6Tanuki, sorry re spelling, felt a bit of a fraud mentioning the 33v clamping chip. But the post asked the first sets to use chips. I still think it may have been a zener inside but circuit references said it was an ic. I know that was the usual cause for tuner drift. Invariably it was the main ht line that was fed to it via a high value resistor of course. I always kept them in stock. Decca Bradfords that used a varicap tuner seemed to eat them. Yet the Pye 697 seemed more forgiving. I'm still in the trade and frequency synthesis has certainly come a long way. Luckily tuner faults are rare now. In fact you need a Leister gun nowadays as the tuner is hard mounted to the signal board. And they stopped using PC86\88 valves a while ago as well. Happy days.

[Graham G3ZVT]

Originally Posted by ms660

Yes, it was called an IC when I was in the trade, transistors etc inside:

https://datasheetspdf.com/pdf-file/769628/ETC/TAA550/1

From the SGS/ATES 1975/76 data book.

Lawrence.

That ladder arrangement gives plenty of scope for failure modes where it appears to regulate, but the voltage drifts slightly with temperature, which was exactly what we used to experience.

You were never entirely sure that the varicap tuner wasn't to blame, so the old TAA550 went back in your spares kit marked ?may be OK?

Or maybe it was just me who did that.

[Nuvistor]

The TAA550 didn’t give me a lot of trouble, the 33k feed going O/C I found failed more than the IC, still replaced a few but not a big problem.
Just shows how different makes and batches of TV’s could develop different faults.

[FERNSEH]

The integrated circuits TAA550 and ZTK33 exploit the temperature co-efficients of Zener diodes above and below 5.6volts.
From Google: "Above 5.6 volts, the avalanche effect becomes predominant and exhibits a positive temperature coefficient. In a 5.6 V diode, the two effects occur together, and their temperature coefficients nearly cancel each other out, thus the 5.6 V diode is useful in temperature-critical applications."

From Wikipedia: https://en.wikipedia.org/wiki/Zener_effect

As for the Rank-Bush-Murphy A823 wasn't the two chip decoder introduced in 1971? The already established SL901 and the SL917. These chips were never used by any other manufacturer.

DFWB.

[greg_simons]

Originally Posted by G6Tanuki

There again, when ICs did make it into the audio-stages of TVs they were not always spectacularly successful - anyone remember the 1970s Texas Instruments SN76001-style "Hedgehog" chips that had a nasty tendency to burn out if you listened to Top of the Pops too loud?

Yes!, They were spectacularly unstable and would hoot off for the slightest thing, must've changed hundreds of the damned things!.

[Synchrodyne]

Originally Posted by G6Tanuki

It sort-of puzzles me that the first TV ICs were for RF/IF signal-processing - somehow I'd always thought the audio stages would have been the initial target, since you only needed transistors with a few tens of KHz frequency-response rather than 5.5 or 6MHz like in the IF strip.

The attached article might help answer that question.


Cheers,

[Maarten]

Originally Posted by FERNSEH

The integrated circuits TAA550 and ZTK33 exploit the temperature co-efficients of Zener diodes above and below 5.6volts.
From Google: "Above 5.6 volts, the avalanche effect becomes predominant and exhibits a positive temperature coefficient. In a 5.6 V diode, the two effects occur together, and their temperature coefficients nearly cancel each other out, thus the 5.6 V diode is useful in temperature-critical applications."

They could have exploited that and maybe some other types actually did, but apparently for the TAA550 and similar chips they'd rather use the zener effect in BE-junctions under controlled circumstances.

[terrykc]

As has been said, the TAA550 was a temperature compensated IC designed to cancel out the temperature coefficient of the varicap diodes.

The first varicap tuners I encountered in 1969 preceded the TAA550 so the compensation was arranged by a string of zeners with voltages above and below the 5.6 volt temperature coefficient threshold - three 6.8V in series with two 3.3 volt types

[FERNSEH]

Late production Plessey SL901. According to the date code this one was made in 1979.

DFWB.

[Nuvistor]

Were there circuit differences between the first SL901 and the B version, something in the back of my mind?

[Maarten]

Originally Posted by terrykc

As has been said, the TAA550 was a temperature compensated IC designed to cancel out the temperature coefficient of the varicap diodes.

The first varicap tuners I encountered in 1969 preceded the TAA550 so the compensation was arranged by a string of zeners with voltages above and below the 5.6 volt temperature coefficient threshold - three 6.8V in series with two 3.3 volt types

That's interesting to know! Never saw that on a continental model but makes sense.

[FERNSEH]

Originally Posted by Nuvistor

Were there circuit differences between the first SL901 and the B version, something in the back of my mind?

Hi Frank,
I was hoping to find the early version of the SL901, the one with the heatsink attached to it. Some decoder boards were pierced to accept either IC. Was the original SL901 designated as SL901A?

DFWB