Transistor oscillator.

Not picturing that somehow - maybe the cold weather is making my mind a bit foggy.

pass the output through a cap to remove dc. Rectify however you wish. Feed to a small reservoir cap. Measure the dc.

NT

If the varicap tuning can get a 3:1 frequency range, and you rectify the transistor output, you ought to be able to see the amplitude (Y axis) being modulated because of the input frequency shift, using the ramp signal as your X axis. This is slightly problematic, because of the expected 3 dB/octave cutoff (i.e. it's a slow cutoff, and a small frequency range).

Your best bet might be a swept varicap oscillator at 300 to 400 MHz, and mixing it down so as to get a 50 to 150 MHz sweep.

I totally agree with you. However, as you have rightly pointed out, a ring oscillator does not drive any load and the frequency is set by the devices' internal capacitances etc., In other words, the oscillation frequency cannot be controlled. The problem lies there.

I am just curious -- was this VCO driving a load ? Sure, VDD, VSS may be tweaked to achieve a goal, but to what end ?

For grading transistors perhaps the circuit shown here

That won't let me save the document unless I sign in to dropbox.

It's the same WW article as was suggested by F. Bloggs.

RL

that problem is definitely at your end.

NT

Ooops - that will teach me to carefully read the whole thread before posting.

I see the OP has rejected this approach already - I'd be most interested to see his alternative solution.

The file exists notification popped up - so evidently something I'd tried had succeeded and not bothered telling me.

Yesterday, W10 decided to re-install itself - its been, go make a cuppa while I wait for things to happen since then.

It did download - but didn't bother telling me.

W10 SNAFU.

Rather your machine than mine. I'm still grumbling about W7.

RL

Originally, W10 was an upgrade on a wobbly W7 - it didn't take long to topple over.

Luckily I'd downloaded the ISO files, so I could do a clean install.

It works - but its slow!

Maybe you only just got the version 1511 'November' (equivalent to a Service Pack) update? It was 3GB so it might've taken a while to get to you and looks like a re-install when it applies itself.

They got millions of people to beta test it - and still couldn't get it right................................