Forgot, basically put it in just to end some debate. Will check again when i get some free time and write here. There are steps to compensate it properly, but in general, people tend to replace (roll) opamps without thinking if it's working properly or not.
They don't know how to compensate it and do like the false clarity given by oscilllation, most of the time. And this is only with internatly compensated op amps w/o the bypass cap. When using an uncompensated inside op amps, roll off makes even less sense ! People don"t realise they don't listen to the op amp as it could sing.
From the beginning it is NOS & Uncompensated... But they basicly need it all, but very few (op861). Also the CFA AD811 needs it !
From the beginning it is NOS & Uncompensated... But they basicly need it all, but very few (op861). Also the CFA AD811 needs it !
There's no mention of 47pf between pins 6 and 8 on Figure 54. There is on Figure 47, but that's a differential configuration.
Would you use 47pf on just the AD797 or would it also apply to e.g. AD845, AD843, AD847 etc.?
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I'm trying to understand opamps a little better. Does the opamp in the DAC circuit operate as a transimpedance amp converting current into volts? Does the following picture make sense? +/- 1mA (AD1862 output) X 1.5 kOhm (feedback resistor) = 1.5 Vp (3 Vp-p output).
I'm trying to calculate gain to be able to properly compensate the opamps used. What is the gain in the example above? Thanks, Tom
I'm trying to calculate gain to be able to properly compensate the opamps used. What is the gain in the example above? Thanks, Tom
There is no gain. The opamp must maintain the same voltage at both inputs, and the noninverting input is at GND. That's why the opamp generates an output voltage that will generate a current through Rf of the same value but in the opposite direction from Iin so that it maintains 0V at the inverting input, i.e. virtual GND.
In that picture, the direction of the current is not drawn correctly.
In that picture, the direction of the current is not drawn correctly.
This is how the inverting amplifier works, only now you have Uin and Rin. Iin is Uin/Rin. The opamp again maintains a virtual GND on the inverting input. But now the voltage gain can be defined as Rf/Rin.
Can I feed the digital input of Miro's WM8804 card with an RCA connector and a short length of twisted pair?
Regards,
Dan
Recently I had been working on a Tube IV stage (PCB send by @Michelag ) and looking for an appropriate R-Core Trafo and I came across this one:
R-Core for Tube/AD1865-62
I have ordered a couple for myself hope it could be of use to others who are still working on an AD1865/62 DAC with a tube IV stage, price is reasonable.
R-Core for Tube/AD1865-62
I have ordered a couple for myself hope it could be of use to others who are still working on an AD1865/62 DAC with a tube IV stage, price is reasonable.
If you prefer to use a resistor load on the tube I/V stage, then you need more like 300V of HT. You can get this easily from a 230:230V toroid with solid state rectification, like this 30VA one from Airlink Transformers, which is the one I use.
https://airlinktransformers.com/pro...toroidal-transformer-standard-range-cm0030172
https://airlinktransformers.com/pro...toroidal-transformer-standard-range-cm0030172
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Thanks, but as we have 240 mains and I will be using 6N23P as the main tube and I have been asked to refrain from using 220 volts trafo (not that I am adept at using tubes, this will be my first project with a tube, all others are based on semiconductors) as the DC would then be (240*1.414=338) which will likely put the tube under stress thus I had to look especially for a trafo with less than 200v and after lot of queries came across one with 170volts, unless I am wrong.
The datasheet says 100V at the anode and the maximum is 300v.
I am using this one for Michelag Tube IV stage: https://www.aliexpress.us/item/2251...t_main.32.4eba1802CJAG7S&gatewayAdapt=glo2usa
Yes, if you are using the usual chi-fi AD1865 with tubes board you want 170V. Just build it like the instructions say.
HT of 300-330V is for more experienced tube builders who want to use resistor loads. It would need modifying the chi-fi board, or using a separate tube I/V stage. You could then use various other dual triodes with mu around 30 which you might prefer the sound of. That's more the kind of stuff you find on the Tubes forum.