Which is rather trivial to achive for a 10k source resistance, at 1 kHz and in anno Domini 2014. 10k has 12.8319 nV/rtHz at 25°C; with the 1 nV/rtHz of a BF862 added, that's 12.8708 nV/rtHz. If the particular specimen should have 1.2 nV/rtHz instead, 12.8878 nV/rtHz results. A deviation of 0.13%, which should not matter for most applications--unless one uses very long integration times, the random fluctuation of the measurement is likely higher.
With the low gm of JFETs it's surprising how significant the second stage contribution is. There are many, many amplifier designs out there where the second stage hurts the performance significantly, particularly in the 1/f region.
Samuel
Hi Demian,
Do you have a PDF of the manual for the Quan-Tech 5173?
I've never used a Quan-Tech but need to be involved in using one with a client later this week.
Cheers,
Bob
Low noise jfets have in general a rather high transconductance. 2*SQRT(Id*Idss)/Vt where Vt is usually under 1V (compare to 3-5V for regular jfets). 20mA/V would be typical, and for a 500ohm load that accounts for a gain of 10. Good enough for reducing any decent second stage noise to a negligible amount.
I have the manual (found it) and will scan either tonight or tomorrow. The scanning hardware is at the old house and the books are already at the new house.
The instrument is pretty easy to use so with the instructions you should be getting good data fast.
Demian
Wondering here which are the low leakage capacitors...
@roadbagger, the Gold Banded caps...I couldn't find the
correct parts, would you be kind enough to provide a
part number or brand and series of capacitor w/link?
@rnmarsh, Richard, were those remakes now by Vishay
the 013 RLC low leakage caps or do they have better
than the 013 RLC specs.
http://www.vishay.com/docs/28313/013rlc.pdf
Sometimes I just can't find the right stuff and when
I use something sometimes it's not the correct part.
So this will help me out somewhere down the road.
Cheers,
@roadbagger, the Gold Banded caps...I couldn't find the
correct parts, would you be kind enough to provide a
part number or brand and series of capacitor w/link?
@rnmarsh, Richard, were those remakes now by Vishay
the 013 RLC low leakage caps or do they have better
than the 013 RLC specs.
http://www.vishay.com/docs/28313/013rlc.pdf
Sometimes I just can't find the right stuff and when
I use something sometimes it's not the correct part.
So this will help me out somewhere down the road.
Cheers,
I just found this part: EBC15MMWD Sullins Connector Solutions | Connectors, Interconnects | DigiKey which solves a lot of problems making adapter cards. The edge connector he used for the interface and its location makes adapting to PCBs for mounting sockets a mechanical and parts challenge. The connector above addresses both the right angle problem and the spacing problem. From here it should be pretty easy to make an assortment of adapters for different devices.
Attachments
I'm ordering a full set of almost every electrolytic in the unit. The cart is here: Digi-Key - Fast Add Several notes-
1) The 25V caps in the power supply have 24VDC on them which is considered bad practice (I checked the voltage to make sure I was not overspec and it seems the original are way under spec).
2) I'm replacing the 8 2200/16V electrolytics that bypass the base/gate to ground with 4 3300uF/16V bipolar caps which will have lower ESR and reactance and should be better in this application.
3) The larger caps are available only in "snap-in" which I hope will fit the PCB holes.
The caps in this unit date from 1985 so an upgrade should be appropriate. Current parts are much smaller for the same values so I went with 105c parts where possible. Another 40 years of service seems reasonable.
1) The 25V caps in the power supply have 24VDC on them which is considered bad practice (I checked the voltage to make sure I was not overspec and it seems the original are way under spec).
2) I'm replacing the 8 2200/16V electrolytics that bypass the base/gate to ground with 4 3300uF/16V bipolar caps which will have lower ESR and reactance and should be better in this application.
3) The larger caps are available only in "snap-in" which I hope will fit the PCB holes.
The caps in this unit date from 1985 so an upgrade should be appropriate. Current parts are much smaller for the same values so I went with 105c parts where possible. Another 40 years of service seems reasonable.
Attached is a corrected pinout drawing for the test connector for the 5173. Like other parts of the documentation this was not correct.
The transistor part was correct but the IC side seems like an afterthought. I figured out how to get the gain test working and a simple mod that makes the input R work for the IC part of the tester. I still have more testing to do to confirm the gain and noise figures I'm getting.
Once I have confidence in this unit I'll make some PCB's for the test fixtures and share them.
The transistor part was correct but the IC side seems like an afterthought. I figured out how to get the gain test working and a simple mod that makes the input R work for the IC part of the tester. I still have more testing to do to confirm the gain and noise figures I'm getting.
Once I have confidence in this unit I'll make some PCB's for the test fixtures and share them.
I'm working on gen 2 of my boards. Let me know if there is interest-
1) single transistor with sockets for TO92 and for TO39 FET and Bipolar
2) Dual transistor/Jfet with a switch to select.
3) Single and dual DIP opamp
4) Quad DIP opamp
I may do some surface mount boards if I can find suitable sockets that aren't really expensive.
JLBPCB is so cheap for these I don't mind a spin or two. And quick. A batch is 10 boards so let me know if interested.
1) single transistor with sockets for TO92 and for TO39 FET and Bipolar
2) Dual transistor/Jfet with a switch to select.
3) Single and dual DIP opamp
4) Quad DIP opamp
I may do some surface mount boards if I can find suitable sockets that aren't really expensive.
JLBPCB is so cheap for these I don't mind a spin or two. And quick. A batch is 10 boards so let me know if interested.
Hi Demian, yes I am interested in acquiring a few instances of each of your boards. I would be delighted to pay 100% of the JLCPCB total charges (boards+shipping) for the entire batch, since you're the one who did the hard work. My ship-to address would be in Santa Clara county. PM?
Thanks,
Mark Johnson
Thanks,
Mark Johnson
I have some of the SOIC 8 adapters. Its the SMD transistor sockets that seem to be elusive or expensive.
Here is the current status.
Single Transistor- waiting for the SMD inductors. I'll share the source for the sockets. These are the third variation I have tried. The first two were not adequate.
IC adapters. Some issue I need to figure out re: 1KHz band. Noise is way high. Something in the docs is not clear. Not the first error in the docs. It may be the reference oscillator not turning off like the docs say it will.
Here is the current status.
Single Transistor- waiting for the SMD inductors. I'll share the source for the sockets. These are the third variation I have tried. The first two were not adequate.
IC adapters. Some issue I need to figure out re: 1KHz band. Noise is way high. Something in the docs is not clear. Not the first error in the docs. It may be the reference oscillator not turning off like the docs say it will.
Attachments
Some links to essential parts:
Sullins connector- Edge Connector You need to saw off one side mounting hole to fit
TO-92 socket Buy Products Online from China Wholesalers at Aliexpress.com Expensive but still the best I have found
TO 39 socket Buy Products Online from China Wholesalers at Aliexpress.com Also expensive. These are pretty good.
Sullins connector- Edge Connector You need to saw off one side mounting hole to fit
TO-92 socket Buy Products Online from China Wholesalers at Aliexpress.com Expensive but still the best I have found
TO 39 socket Buy Products Online from China Wholesalers at Aliexpress.com Also expensive. These are pretty good.
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Demian, those Aliexpress links don't work. I think it's because you linked to line-items of an invoice (??) and Aliexpress will only show your invoice to >>you<< , after you've logged in.
Me, when I click those links, I get a "login now" window and a URL that makes me think I've asked for a specific Order-ID from a specific Aliexpress customer.
This is what pastes into my browser's address bar when I click your link:
. . . . . . login.aliexpress.com/?return_url=http://www.aliexpress.com/snapshot/0.html?orderId=8126477198649970&from=aliexpress . . . . . .
Me, when I click those links, I get a "login now" window and a URL that makes me think I've asked for a specific Order-ID from a specific Aliexpress customer.
This is what pastes into my browser's address bar when I click your link:
. . . . . . login.aliexpress.com/?return_url=http://www.aliexpress.com/snapshot/0.html?orderId=8126477198649970&from=aliexpress . . . . . .
Ali express is not easy to work with. It may even be the Chinese govt. snooping since I did try to share the web pages. In any case I hope these links work. I tried testing them in Edge. There is no catalog and part numbers are murky at best:
2.54mm triode socket aging detection socket TO 92 TO 220 TO 3P TO 3P 4 TO 3P 5 test socket|Demo Board| - AliExpress
TO39 S3 TO 3 CAN 3 Burn in Socket CAN3 IC Test Socket/IC Socket|socket|socket icsocket test - AliExpress
I have also found that Digikey's order history doesn't work in Chrome and does on Edge, which is just weird since they share most of the code. Let me know if these links don't work.
2.54mm triode socket aging detection socket TO 92 TO 220 TO 3P TO 3P 4 TO 3P 5 test socket|Demo Board| - AliExpress
TO39 S3 TO 3 CAN 3 Burn in Socket CAN3 IC Test Socket/IC Socket|socket|socket icsocket test - AliExpress
I have also found that Digikey's order history doesn't work in Chrome and does on Edge, which is just weird since they share most of the code. Let me know if these links don't work.
> those Aliexpress links don't work
And I don't see an "easy" fix. But it is incompetence, not censorship.
The URLs given end in "productId=4001122888920". Go to "aliexpress.com" and put that number "4001122888920" in the Search box. I get "2.54mm triode socket aging detection socket TO-92 TO-220 TO-3P TO-3P-4 TO-3P-5 test socket" which seems pretty likely.
The syntax MAY be https://www.aliexpress.com/item/4001122888920.html
https://www.aliexpress.com/item/32811718573.html
And I don't see an "easy" fix. But it is incompetence, not censorship.
The URLs given end in "productId=4001122888920". Go to "aliexpress.com" and put that number "4001122888920" in the Search box. I get "2.54mm triode socket aging detection socket TO-92 TO-220 TO-3P TO-3P-4 TO-3P-5 test socket" which seems pretty likely.
The syntax MAY be https://www.aliexpress.com/item/4001122888920.html
Code:
https://www.aliexpress.com/item/4001122888920.htmlhttps://www.aliexpress.com/item/32811718573.html
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