John Curl's Blowtorch preamplifier part II

[simon7000]

You will not get correct results with the AP if the loss mechanism is rate of change dependent as eddy dissipation is. While the differential with sine plus noise is interesting, you most likely will not be able to develop an analytical relationship to describe the difference. That means that the chances are great that you will come to incorrect conclusions.

That is why I recommended sine first.

jn

The AP is capable of doing a swept sine and non FFT level measurement! It is not just an FFT box!

 

[jneutron]

The AP is capable of doing a swept sine and non FFT level measurement! It is not just an FFT box!

Good. But as I said, measurement of only the bybee or the reference will be useless due to the low impedance and the parasitics. The only choice you have is comparison by differential. And using extreme care to make the setup very symmetrical with respect to magnetic field.

jn

 

[simon7000]

Good. But as I said, measurement of only the bybee or the reference will be useless due to the low impedance and the parasitics. The only choice you have is comparison by differential. And using extreme care to make the setup very symmetrical with respect to magnetic field.

jn

We are talking about signal levels of 25 mV much higher than I usually play with!

 

[jneutron]

We are talking about signal levels of 25 mV much higher than I usually play with!

We are discussing the accurate measurement of a .025 ohm, 600 nanohenry inductor over frequency. You do not have the equipment to measure that puppy in isolation accurately. If you do not work it differentially against a reference, your data and conclusions will be useless.

jn

 

[john curl]

More like 6nH, I would guess.

 

[simon7000]

We are discussing the accurate measurement of a .025 ohm, 600 nanohenry inductor over frequency. You do not have the equipment to measure that puppy in isolation accurately. If you do not work it differentially against a reference, your data and conclusions will be useless.

jn

Which is a technique I have had a great deal of practice with.

600 nH at 100 Hz is .00038 ohms. That would not account for the difference in level of a 160 Hz low pass filtered noise signal.

I'll post a picture of the test jig next time I set it up.

 

[jneutron]

Which is a technique I have had a great deal of practice with.

600 nH at 100 Hz is .00038 ohms. That would not account for the difference in level of a 160 Hz low pass filtered noise signal.

I'll post a picture of the test jig next time I set it up.

I have no confidence in your measurement of 600 nanohenries. Nor have you demonstrated the tools or techniques to measure Rs in the frequency band of interest. As I said, .025 ohm impedance circuitry is not easy.

I occasionally do work in the sub nanohenry regime, so know very well what problems you will run into.

Pics would be nice. DON'T make me drive there!!!!!

jn

 

[simon7000]

You are always welcome.

 

[jcx]

at least he's only away - not far away

 

[fas42]

The demon's making bold moves now - he's clobbered page 4217 for me - browser says, not found ...

 

[Kindhornman]

Don't they sell a Demon detector at Fry's these days...... A couple of Bucky Balls and some Graphene and you can sort all the good from the bad....😀

 

[sofaspud]

I'm diggin' the meat and potatoes T&M. Just so ya know. The chips can fall where they may. (Almost an unintended pun.)

 

[gootee]

The demon's making bold moves now - he's clobbered page 4217 for me - browser says, not found ...

For me, your post is ON page 4217(!).

 

[fas42]

Well, I couldn't see that page, tried again and again, and posted about such, from 4216 - and of course that ended up on 4217 ... demon's now gone to sleep, so all OK ... 😉

 

[qusp]

I'm diggin' the meat and potatoes T&M. Just so ya know. The chips can fall where they may. (Almost an unintended pun.)

+1

always love this stuff, particularly interesting for those lacking 10k analysers

 

[john curl]

Dick Sequerra says HI to Scott Wurcer. You should call him sometime.

 

[fas42]

... 'pears as if the demon has gone on a ramage throughout diyAudio - simon, what have you unleashed ... 😡,😛 !!?

 

[Joao@AltheaMusica]

Allow me a question OT: any alternative / comerative for 2N6550 (N-channel JFET)?

Thanks in advance...

 

[jneutron]

+1

always love this stuff, particularly interesting for those lacking 10k analysers

For me, one of the most amazing learning experiences is to go through the HP manuals where they discuss the theory of the instrument.

jn

 

[jneutron]

... 'pears as if the demon has gone on a ramage throughout diyAudio - simon, what have you unleashed ... 😡,😛 !!?

Don't worry. The middle simon can put the antimatter into the bybee slipstream. Luckily, bybees have a slipstream..

jn