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Old 10th June 2012, 09:54 PM   #7721
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Thanks Salas and Andrew for your comments and instructions.

Did some tests on a sample of 28 transistors.
I used a 9V battery with 100R in series to Drain, with G and S shorted to battery negative.

Measured also resistance from D to S and found always values in the region of thirties ohms.

The values were read with my DMM on both resistor terminals as bellow:
- 0,840V. - 0,984V. - 0,647V. - 0,938V
- 0,770V. - 0,944V. - 0,830V. - 0,804V
- 0,730V. - 0,638V. - 0,900V. - 0,965V
- 0,684V. - 0,957V. - 0,655V. - 0,925V
- 0,720V. - 0,884V. - 0,720V. - 1,014V
... And so on.

What do you think? If I use I=V/R, in one of the values, say 0,840V divided by 100R, I get 0,00840A. Is this correct?

I believe that the higher values are the most suitable, correct?
Thanks once more, I will try to show you my wok as this goes on.
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Old 10th June 2012, 11:08 PM   #7722
Salas is offline Salas  Greece
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Obviously correct. 8.4mA.

8-8.5mA are working in the PDF circuits OK.
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Old 11th June 2012, 06:01 AM   #7723
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Old 11th June 2012, 10:05 AM   #7724
AndrewT is offline AndrewT  Scotland
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How well did your battery hold it's "starting" voltage till the completion of the 28 measurements?
If it started @ 9.0V and held at >8.9V till the end then Vds was in the range ~8.3Vds to 7.8Vds. Good enough for rough batching to 2 sig fig.

However if the battery voltage fell to ~8V, then the Vds range changes to ~8.3Vds to 6.8Vds. This range of Vds being very significantly different from the 10Vds specified for Idss will increase the "errors" in your results and between your results.

A quick scan of your 20 posted results shows Idss between 6.3mA and 10.1mA
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Last edited by AndrewT; 11th June 2012 at 10:07 AM.
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Old 11th June 2012, 07:50 PM   #7725
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Quote:
Originally Posted by AndrewT View Post
How well did your battery hold it's "starting" voltage till the completion of the 28 measurements?
If it started @ 9.0V and held at >8.9V till the end then Vds was in the range ~8.3Vds to 7.8Vds. Good enough for rough batching to 2 sig fig.

However if the battery voltage fell to ~8V, then the Vds range changes to ~8.3Vds to 6.8Vds. This range of Vds being very significantly different from the 10Vds specified for Idss will increase the "errors" in your results and between your results.

A quick scan of your 20 posted results shows Idss between 6.3mA and 10.1mA
Just measured the battery and it's 9,09V!
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Old 15th June 2012, 08:26 PM   #7726
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Hi Salas,
I'll be building one more preamp for the second arm I'm about to add to my TT. This time, HO MC Micro Benz Silver, 2mV cartridge will be used. I was wandering shall I go RIAA-V1102F0 route again or is there a more suitable design of yours, for 2mV cartridges?
Thank you
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Old 15th June 2012, 08:29 PM   #7727
Salas is offline Salas  Greece
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That in the PDF is OK. If you will need say 45dB instead of 43, you can scale down first stage's Rs a bit.
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Old 15th June 2012, 08:35 PM   #7728
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OK, thaks a lot.
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Old 23rd June 2012, 11:48 AM   #7729
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Question pre-pre low MC 20dBs

How can be modified the pre-pre low MC 20dBs schematic to run with batteries?
Attached Images
File Type: jpg Salas Simplisitic pre-pre Low MC 20dBs.jpg (253.1 KB, 164 views)
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Old 23rd June 2012, 11:52 AM   #7730
AndrewT is offline AndrewT  Scotland
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Remove every component to the right of C4.
Apply a 9V battery.
C4 could probably be increased to 100uF.
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