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Revisiting some "old" ideas from 1970's - IPS, OPS
Revisiting some "old" ideas from 1970's - IPS, OPS
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Old 3rd October 2016, 08:50 PM   #1461
thimios is offline thimios  Greece
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Originally Posted by vzaichenko View Post
Looks excellent!

I think, we will add one more resistor placeholder in series with both both R6 and R15 - the optimal value would be some 5.8...5.9 Kohm - easier to add-up by 2 resistors.
It's pretty well-balanced by itself - only 56mV at the servo output, easy job for the servo.
I think, it's going to become our "flagship" IPS board for Modular series.

Is the front-end running cooler in terms of temperature, just by touching the local heatsinks?
Do you mean that i must place two 5k6 resistors in series for eatch R6&R15?
Please post a draft schematic.
I will make temperature measurements soon.
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Old 3rd October 2016, 09:01 PM   #1462
jwilhelm is offline jwilhelm  Canada
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No more DC offset issues at clipping?
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Old 3rd October 2016, 09:09 PM   #1463
thimios is offline thimios  Greece
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No more DC offset issues at clipping?
Offset d.c never was a measurement issue
Just all hysteresis capacitors changed to 1-2.2uf.
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Old 3rd October 2016, 09:19 PM   #1464
vzaichenko is offline vzaichenko  Russian Federation
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Revisiting some "old" ideas from 1970's - IPS, OPS
Quote:
Originally Posted by thimios View Post
Do you mean that i must place two 5k6 resistors in series for eatch R6&R15?
Please post a draft schematic.
I will make temperature measurements soon.
That's what I mean (red arrows)
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Old 3rd October 2016, 09:32 PM   #1465
thimios is offline thimios  Greece
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Ok got it.
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Old 3rd October 2016, 09:37 PM   #1466
vzaichenko is offline vzaichenko  Russian Federation
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Revisiting some "old" ideas from 1970's - IPS, OPS
Quote:
Originally Posted by thimios View Post
Ok got it.
Yes - light trimming of LTP currents, so that the voltage drop over resistors, marked 0.5V, becomes closer to 1/2 of the voltage drop over the resistors, marked as 1V (now it's roughly 0.6V vs 1V).
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Old 4th October 2016, 01:24 PM   #1467
thimios is offline thimios  Greece
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Default Updated vz-x4

Is it ok?
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Old 4th October 2016, 01:27 PM   #1468
vzaichenko is offline vzaichenko  Russian Federation
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Revisiting some "old" ideas from 1970's - IPS, OPS
Yes - very good, I think.
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Old 4th October 2016, 01:39 PM   #1469
thimios is offline thimios  Greece
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Originally Posted by vzaichenko View Post
Yes - very good, I think.
If we keep this as final modification it is necessary to modify the Vbe multiplier too.
Now the end of Vbe trimmer is nothing more than 21mV over 0.44R emitter resistors.
Temperature on four transistors is 47c when room temperature is 23c

Last edited by thimios; 4th October 2016 at 01:47 PM.
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Old 4th October 2016, 01:49 PM   #1470
vzaichenko is offline vzaichenko  Russian Federation
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Revisiting some "old" ideas from 1970's - IPS, OPS
Well, now the VAS output went a bit below 5mA.
We can either slightly tune-up R24 || R25 for increasing it back to some 5...5.5 mA.

Or - leave 5.6K, as you had before - it runs great anyway.
This is just a very fine tuning ))
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