Simple gyrator circuit

Great stuff Paul.... back to a single transistor.

Can't vouch for the accuracy of the api drawing, but am going to fiddle with values.

Thanks muchly... :thumb: :thumb: :thumb:

Maybe the Self link didn't work because it was old---clearly his site is still functional.

If a single Q will do the job, by all means. The input impedance tends to be the spoiler when you're trying to extract higher Q. The feedback pair, with just a couple more parts, tends to be as good as a decent fast op amp and is usually quieter. If you use it I would make your R9 a little smaller---the 4416 can do with a few mills for decent noise performance. It is a little challenged for voltage in this app but will usually be o.k except under extremes of signal drive. There are some 50V rated parts that would be bulletproof.

Cheers Brad,
I'm going to build them both and go with the one with less smoke.

peter

[quote author="peter purpose"]Cheers Brad,
I'm going to build them both and go with the one with less smoke.

peter[/quote]

I'd change the 3.3k to about 300 ohms for around 2mA in the 4416 or comparable FET. Should work just fine. Self's recommended values are ~appropriate for both Q's bipolar.

Thanks Brad.... you're a diamond.. :thumb:

Well gentlemen,
I built both versions and while both sounded sweet, I went for the 'paulductor'.
I used polystyrene to make up the 6nF. Originaly had a BC546B as the q, but when swapped for a 2N2222 it really came to life.
This is a really nice low shelf. I can't make anything sound bad, even with extremes of boost.
I turned the other version into a 1k6 peak and it interacts v. nicely with the low shelf, except for harshness at extreme boost (which was mentioned) and some funny business when at full cut which was sorted with a series 100R.
All in all this is turning into a nice little eq.

Now for a HMF peak and a nice HF shelf.

Cheers
peter

but when swapped for a 2N2222 it really came to life

Click to expand...

... hmm ...
http://jlnlabs.online.fr/cnr/negosc.htm