1 V oscillator.

That sounds trivial. It is trivial. Not for me. I need a schematic to build. Surely there must be some current into the base for startup?

Groetjes Albert

I realise this is completely off-topic but in your signature I see: "First gain is a cat spinning. ". This is an expression I have never heard before, could you tell me what it means?

I can add one factoid: In Swedish (and perhaps all Nordic languages), one literally says that a cat "spins" to say that it is purring.

Joe Gwinn

One issue with old germanium transistors is that they have horrible base leakage, enough to make the apparent beta negative in many cases.

Cheers

Phil Hobbs

I recall such a patent, but it was to exercise the cat, who kept trying to catch the moving laser spot on the floor, to no avail.

Don't think the frustrated cat was purring.

.

Joe Gwinm

This, perhaps?

Could this be a reference to the rising and falling purring noise a spinning wheel makes?

To first order, it doesn't really matter which terminal you select to be at AC GND.

The active device has gain -S*Ui*Zl, with Zl being a tank circuit. Ui is derived from a tap on that tank, which allows you to work out the loop gain. The loop gain needs to be unity at the tank resonance. (Usually a bit greater, until some non-linearity at large amplitude reduces it to unity.)

In the picture you referred to above, Zl is the series combination of L and C2, with C1 in parallel across both. Ui is the voltage across C2. They way it is drawn doesn't really help. It's the same circuit, but I prefer to draw it like this: +-----+-----+ | | | L | | | d | +----g = C1 | s | = C2 | | | | | +-----+-----+ Substitute cbe for dgs if you want, it's the same thing.

Jeroen Belleman

I don't know the origin. Not German. Nor Icelandic (which is basically Old Norse). But it is true in Norwegian, and Danish.

It may be a parallel to the sound of a well-tuned engine, which in English we often describe as purring.

I'll think about it. Somewhere I have an old Swedish dictionary that may have the etymology, or at least a clue.

An interesting rough parallel is that beer in German is Bier, but in Swedish its öl. And oil in German is Öl, but in Swedish its olja. Much of Swedish vocabulary is Germanic, so one's first guess would be that the same word would be used in both. Norwegian and Danish also do this.

Now there are many sayings that hold that beer is a social lubricant, oiling the gears so to speak, and it may be that Swedish, Norwegian, and Danish mutated to make the colloquial the standard word. Basically, it appears to have been a Viking invention.

Joe Gwinn.

One time I inherited about a dozen that looked NOS from an audio repair shop estate, unfortunately they all had internal shorts, maybe tin whiskers.

Yes, but at 1V even regular silicon transistors can be used ( at least at normal temperatures).

This reminds me I picked up some AF379 transistors out of curiosity- they are plastic encapsulated germanium with Ft of 1.2GHz - had vague plans of making a UHF GDO running of a single AA cell.

I had a feeling the O/P was Dutch.

Nice. Apart from the gimmick, the reactive components seem to be layout and component parasitics. That always makes me uncomfortable, because it makes it hard to reproduce reliably.

I'd guess the gimmick is still capacitive at 2.4GHz?

Jeroen Belleman

Thanks, that should be enough to get me going.

Groetjes Albert

That is a translation error. Meant is a "cat purring". Thanks for pointing this out. [The "Wijze van Antrim" actually exists, in Dutch literature.]

Groetjes Albert

Once the oscillator works I intend to lower the voltage. That is the one of the experiments I want to do.

On the other matter, I do not necessarily mean a sine oscillator. Anything goes, I hear oscillators based on core saturation. This probably means that I have to use rather small ring cores?

There are oscillators based on core saturation. The original Royer inverter paper envisaged an inverter that relied on driving the core into saturation alternately in each direction, but letting the switching transistorx run out of drive worked rather better.

Any ferromagnetic core material will saturate at a high enough flux - there's nothing special about a ring core except that you get less cross-section to saturate for every gram of relatively expensive ferrite that you buy.

It's pretty horribly temperature dependent, so you don't get a stable oscillation frequency.

Thanks, does it mean something like: "You know you are winning when the cat begins to purr"?

It is always interesting to see wise sayings from other languages. Dutch seems to be particularly rich in these - the Dutch sense of humour is very similar to a certain type of English humour that appeals to me.

...and no air gap.