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[sevenlayermuddle]

Perhaps the circuit diagram will allow 7LM to reminisce on the subject of discrete semiconductor devices? 

Does that carry some insinuation about my vintage?


Seriously, I enjoyed the days when you could tell, from looking at the schematic, what a circuit was meant to do.

Mind you, that's also my main criticism of OO software... a single line of code, that looks so innocent, can do so much.   Bring back TTL and machine code, then I'll stand a chance.

[Black Sheep]

Transistor-Transistor Logic ........ I remembered that from my ONC in electrical engineering. Get in there !!! 

Seriously, that's about all I can remember, apart from the Capacitor and Resistor in series (variable ??) being a kind of timer before the 666 chips came into being ?? Long time ago and way, way, way out of my comfort zone.

[Blackeagle]

Transistor-Transistor Logic ........ I remembered that from my ONC in electrical engineering. Get in there !!! 

Seriously, that's about all I can remember, apart from the Capacitor and Resistor in series (variable ??) being a kind of timer before the 666 chips came into being ?? Long time ago and way, way, way out of my comfort zone.

Are you perhaps referring there to the NE555 BS ? 

You can build a simple band pass filter with a resistor and a capacitor in series.  If you take the output from across the cap you would get a low-pass filter, if taken across the resistor, a high-pass filter.

[Black Sheep]

Transistor-Transistor Logic ........ I remembered that from my ONC in electrical engineering. Get in there !!! 

Seriously, that's about all I can remember, apart from the Capacitor and Resistor in series (variable ??) being a kind of timer before the 666 chips came into being ?? Long time ago and way, way, way out of my comfort zone.

Are you perhaps referring there to the NE555 BS ? 

You can build a simple band pass filter with a resistor and a capacitor in series.  If you take the output from across the cap you would get a low-pass filter, if taken across the resistor, a high-pass filter.

Ha ha, that's the one Black Eagle. I didn't know that about the 'Band-pass' filter though. I can only assume that's how the ADSL dongle filters are assembled ??

[sevenlayermuddle]

Are you perhaps referring there to the NE555 BS ? 

Ah yes, the appearanceof 555 timers does bring back memories, especially of a very elaborate windscreen wiper controller I designed for a 1970 Ford Escort.   It featured variable intermittent wipe as well as a variable 'on' time after you used the washers.

Come to think of it... , I probably should have patented that, they all do it now

[burakkucat]

Perhaps the circuit diagram will allow 7LM to reminisce on the subject of discrete semiconductor devices? 

Does that carry some insinuation about my vintage?

Well as I am a "valve cat", these new-fangled semiconducting devices are a mystery to me! With valves you knew when they were powered on (they glowed). In the winter, they provided a source of warmth to "cold paws". All the other discrete components were of similar size (at least I could see the resistors, capacitors, inductors, bulbs, transformers . . . ) 

[sevenlayermuddle]

Perhaps the circuit diagram will allow 7LM to reminisce on the subject of discrete semiconductor devices? 

Does that carry some insinuation about my vintage?

Well as I am a "valve cat", these new-fangled semiconducting devices are a mystery to me! With valves you knew when they were powered on (they glowed). In the winter, they provided a source of warmth to "cold paws". All the other discrete components were of similar size (at least I could see the resistors, capacitors, inductors, bulbs, transformers . . . ) 

Couldn't agree more.  And not only were the components big enough to see, the capacitors usually had values in plain english, while the resistors  had only three big, bold, colour stripes (ignoring the fourth, gold or silver).  These days, many low value cap's also seem to be marked in codes known only to the secret services.  As for the resistors, they not only seem to have made them unnecessarily tiny, they've crammed in more colour bands.

Any chance of a peek inside the LMS35A device?  Even just a soft-focus pass on the scanner might be interesting?

[roseway]

Is this turning into a wrinklies' nostalgia session?

My first radio didn't have valves. It used a small crystal and a fine wire with a sharp point, which I had to move around over the crystal to find a sensitive point. We didn't just build the equipment, we had to make the components too.

[burakkucat]

Any chance of a peek inside the LMS35A device?  Even just a soft-focus pass on the scanner might be interesting?

Certainly. I've scratched made a note to remind myself to remove the back and see what is scan-able.

[burakkucat]

We didn't just build the equipment, we had to make the components too.

And what fun it was! When the "main station" was the BBC's Light Programme, broadcasting via the Droitwich transmitter on 200 kHz (1500 metres Long Wave), winding the coil, setting up a long wire aerial to the end of the garden and establishing a good earth connection was an afternoon's occupation. 

[burakkucat]

Any chance of a peek inside the LMS35A device?  Even just a soft-focus pass on the scanner might be interesting?

It must be a day for miracles, for b*cat has remembered 7LM's request and so is happy to offer the best image that his flat-bed scanner could obtain. 

[sevenlayermuddle]

Any chance of a peek inside the LMS35A device?  Even just a soft-focus pass on the scanner might be interesting?

It must be a day for miracles, for b*cat has remembered 7LM's request and so is happy to offer the best image that his flat-bed scanner could obtain. 

Thanks for that.

It reminds me to add 'single layer pcbs' to my wish list, for a return to the old days, and the ability to make a very good guess about a device's function just by looking at it (and holding it up to the light) 

I also like the amount of pcb real-estate given over to the big push button.  But I also recall some of these big chunky switches with their large slider contacts did tend to corrode readily.  Same may go for the rotary switches.  A squirt of switch cleaner may be called for?

[burakkucat]

Ah, yes. Rotary switches with multiple wafers of the Yaxley disposition. A quick squirt of Electrolube switch cleaner worked wonders. 

[sevenlayermuddle]

It's late, and so apologies in advance if I'm overlooking the obvious and asking a stupid question, but what does the large push button actually correspond to on the schematics?

The schematics show two apparently independent single pole 'on' buttons, S3 and S4, either one of which would seem adequate, and annotated LH and RH.  Any clues?

7LM

[Blackeagle]

Well as I am a "valve cat", these new-fangled semiconducting devices are a mystery to me! With valves you knew when they were powered on (they glowed). In the winter, they provided a source of warmth to "cold paws". All the other discrete components were of similar size (at least I could see the resistors, capacitors, inductors, bulbs, transformers . . . ) 

Ah, so your favourite voltage is 6.3v ??

Valves were a little before my time although I did build an amp based around EL84's !!

My dad was a TV & Video engineer who did his appreticeship in the 50's.  I well remember him stripping our 28" decca console on a regular basis with its bradford chassis. Mullard PL508 anyone ??

Electrolube !!  Good stuff, and there is a can of it in my toolbox, along with freezer and Servisol screen cleaner !!  Meters are AVO 7 & AVO 8 & a digital (early) fluke although I cannot tell from the fluke if a transistor is good or bad.  Can from the AVO's though !!