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Two feedback paths (again)

J

josephkk

Jan 1, 1970
0
The opamp is an LT1013 (input voltage can go down near the negative
power rail)
and the transistors are TIP31C's...
Both just pieces I have from other projects.

George H.

Thanks for the component types. Please note that the new circuit has no
shown dc feedback path for the opamp.

If you don't mind i recommend the following version in a LTSpice asc file:


Version 4
SHEET 1 1672 680
WIRE 64 0 -160 0
WIRE 384 0 64 0
WIRE 640 0 384 0
WIRE 704 0 640 0
WIRE 928 0 704 0
WIRE 1168 0 992 0
WIRE 1600 0 1168 0
WIRE 704 16 704 0
WIRE 384 32 384 0
WIRE 64 48 64 0
WIRE 352 48 320 48
WIRE -160 64 -160 0
WIRE 528 64 416 64
WIRE 640 64 608 64
WIRE 352 80 288 80
WIRE 736 112 704 112
WIRE 192 128 64 128
WIRE 736 144 736 112
WIRE 736 160 736 144
WIRE 992 160 736 160
WIRE 1120 160 1088 160
WIRE 1168 160 1120 160
WIRE 1216 160 1168 160
WIRE 1344 160 1216 160
WIRE 320 192 320 48
WIRE 464 192 320 192
WIRE 736 192 736 160
WIRE 736 192 528 192
WIRE 1344 192 1344 160
WIRE 288 208 288 80
WIRE 288 208 192 208
WIRE 736 224 736 192
WIRE 928 224 736 224
WIRE 192 240 192 208
WIRE 736 240 736 224
WIRE 1600 240 1600 0
WIRE 64 256 64 128
WIRE 1216 256 1216 160
WIRE 320 288 320 192
WIRE 464 288 320 288
WIRE 576 288 544 288
WIRE 1344 288 1344 256
WIRE 1040 304 1040 224
WIRE 1040 304 928 304
WIRE -160 352 -160 144
WIRE 928 352 928 304
WIRE 320 368 320 288
WIRE 1344 416 1344 368
WIRE 576 448 576 288
WIRE 1120 448 1120 160
WIRE 1120 448 576 448
WIRE -160 512 -160 432
WIRE 64 512 64 320
WIRE 64 512 -160 512
WIRE 192 512 192 320
WIRE 192 512 64 512
WIRE 320 512 320 448
WIRE 320 512 192 512
WIRE 384 512 384 96
WIRE 384 512 320 512
WIRE 736 512 736 320
WIRE 736 512 384 512
WIRE 928 512 928 416
WIRE 928 512 736 512
WIRE 1216 512 1216 336
WIRE 1216 512 928 512
WIRE 1344 512 1344 496
WIRE 1344 512 1216 512
WIRE 1600 512 1600 320
WIRE 1600 512 1344 512
WIRE 192 544 192 512
FLAG 192 544 0
FLAG 1168 160 vout
FLAG 640 0 vsupply
FLAG 736 144 vq1e
FLAG 1168 0 vsripple
SYMBOL res 48 32 R0
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL res 176 112 R0
SYMATTR InstName R2
SYMATTR Value 75k
SYMBOL res 176 224 R0
SYMATTR InstName R3
SYMATTR Value 25k
SYMBOL res 720 224 R0
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL res 912 208 R0
SYMATTR InstName R5
SYMATTR Value 500
SYMBOL res 624 48 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R6
SYMATTR Value 500
SYMBOL cap 912 352 R0
SYMATTR InstName C1
SYMATTR Value 100?
SYMATTR SpiceLine V=35
SYMBOL cap 528 176 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C2
SYMATTR Value 10n
SYMATTR SpiceLine V=50
SYMBOL res 448 304 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 0 56 VBottom 0
SYMATTR InstName R7
SYMATTR Value 10k
SYMBOL npn2 640 16 R0
SYMATTR InstName Q1
SYMATTR Value TIP31C
SYMBOL npn2 992 224 R270
SYMATTR InstName Q2
SYMATTR Value TIP31C
SYMBOL voltage -160 48 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 132 Left 0
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V1
SYMATTR Value 12
SYMBOL References\\LT1009 64 288 R0
SYMATTR InstName U2
SYMBOL res 1200 240 R0
SYMATTR InstName R8
SYMATTR Value 100
SYMBOL res 304 352 R0
SYMATTR InstName R9
SYMATTR Value 2.5k
SYMBOL voltage 1344 272 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value SFFM(0 1 20k 0.3 1k)
SYMBOL cap 1328 192 R0
SYMATTR InstName C3
SYMATTR Value 1m
SYMATTR SpiceLine V=25
SYMBOL res 1328 400 R0
SYMATTR InstName R10
SYMATTR Value 250
SYMBOL voltage -160 336 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value SFFM(0 0.1 10k 0.3 500)
SYMBOL cap 992 -16 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C4
SYMATTR Value 100?
SYMBOL res 1584 224 R0
SYMATTR InstName R11
SYMATTR Value 1k
SYMBOL Opamps\\LT1013 384 0 R0
SYMATTR InstName U1
TEXT -192 568 Left 0 !.tran 0 10m 0 1u

---
There is a little vout ripple due to the load disturance generator i
included. The source disrurbance generator does not seem to affect
matters much.

?-)
 
J

josephkk

Jan 1, 1970
0
Or to integrate first and then differentiate in the second stage.

Cheers

Phil Hobbs

And that has different costs. DC is lost unless you do feed-beside for
that. Think 'scope vertical amplifiers.

?-)
 
G

George Herold

Jan 1, 1970
0
RE: DC feedback... I was a bit lazy and just put the words
"to invertng input"<----
Thanks for the component types.  Please note that the new circuit has no
shown dc feedback path for the opamp.

See above for DC feed back.
If you don't mind i recommend the following version in a LTSpice asc file:

Version 4
SHEET 1 1672 680
WIRE 64 0 -160 0
WIRE 384 0 64 0
WIRE 640 0 384 0
WIRE 704 0 640 0
WIRE 928 0 704 0
WIRE 1168 0 992 0
WIRE 1600 0 1168 0
WIRE 704 16 704 0
WIRE 384 32 384 0
WIRE 64 48 64 0
WIRE 352 48 320 48
WIRE -160 64 -160 0
WIRE 528 64 416 64
WIRE 640 64 608 64
WIRE 352 80 288 80
WIRE 736 112 704 112
WIRE 192 128 64 128
WIRE 736 144 736 112
WIRE 736 160 736 144
WIRE 992 160 736 160
WIRE 1120 160 1088 160
WIRE 1168 160 1120 160
WIRE 1216 160 1168 160
WIRE 1344 160 1216 160
WIRE 320 192 320 48
WIRE 464 192 320 192
WIRE 736 192 736 160
WIRE 736 192 528 192
WIRE 1344 192 1344 160
WIRE 288 208 288 80
WIRE 288 208 192 208
WIRE 736 224 736 192
WIRE 928 224 736 224
WIRE 192 240 192 208
WIRE 736 240 736 224
WIRE 1600 240 1600 0
WIRE 64 256 64 128
WIRE 1216 256 1216 160
WIRE 320 288 320 192
WIRE 464 288 320 288
WIRE 576 288 544 288
WIRE 1344 288 1344 256
WIRE 1040 304 1040 224
WIRE 1040 304 928 304
WIRE -160 352 -160 144
WIRE 928 352 928 304
WIRE 320 368 320 288
WIRE 1344 416 1344 368
WIRE 576 448 576 288
WIRE 1120 448 1120 160
WIRE 1120 448 576 448
WIRE -160 512 -160 432
WIRE 64 512 64 320
WIRE 64 512 -160 512
WIRE 192 512 192 320
WIRE 192 512 64 512
WIRE 320 512 320 448
WIRE 320 512 192 512
WIRE 384 512 384 96
WIRE 384 512 320 512
WIRE 736 512 736 320
WIRE 736 512 384 512
WIRE 928 512 928 416
WIRE 928 512 736 512
WIRE 1216 512 1216 336
WIRE 1216 512 928 512
WIRE 1344 512 1344 496
WIRE 1344 512 1216 512
WIRE 1600 512 1600 320
WIRE 1600 512 1344 512
WIRE 192 544 192 512
FLAG 192 544 0
FLAG 1168 160 vout
FLAG 640 0 vsupply
FLAG 736 144 vq1e
FLAG 1168 0 vsripple
SYMBOL res 48 32 R0
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL res 176 112 R0
SYMATTR InstName R2
SYMATTR Value 75k
SYMBOL res 176 224 R0
SYMATTR InstName R3
SYMATTR Value 25k
SYMBOL res 720 224 R0
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL res 912 208 R0
SYMATTR InstName R5
SYMATTR Value 500
SYMBOL res 624 48 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R6
SYMATTR Value 500
SYMBOL cap 912 352 R0
SYMATTR InstName C1
SYMATTR Value 100?
SYMATTR SpiceLine V=35
SYMBOL cap 528 176 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C2
SYMATTR Value 10n
SYMATTR SpiceLine V=50
SYMBOL res 448 304 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 0 56 VBottom 0
SYMATTR InstName R7
SYMATTR Value 10k
SYMBOL npn2 640 16 R0
SYMATTR InstName Q1
SYMATTR Value TIP31C
SYMBOL npn2 992 224 R270
SYMATTR InstName Q2
SYMATTR Value TIP31C
SYMBOL voltage -160 48 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 132 Left 0
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V1
SYMATTR Value 12
SYMBOL References\\LT1009 64 288 R0
SYMATTR InstName U2
SYMBOL res 1200 240 R0
SYMATTR InstName R8
SYMATTR Value 100
SYMBOL res 304 352 R0
SYMATTR InstName R9
SYMATTR Value 2.5k
SYMBOL voltage 1344 272 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value SFFM(0 1 20k 0.3 1k)
SYMBOL cap 1328 192 R0
SYMATTR InstName C3
SYMATTR Value 1m
SYMATTR SpiceLine V=25
SYMBOL res 1328 400 R0
SYMATTR InstName R10
SYMATTR Value 250
SYMBOL voltage -160 336 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value SFFM(0 0.1 10k 0.3 500)
SYMBOL cap 992 -16 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C4
SYMATTR Value 100?
SYMBOL res 1584 224 R0
SYMATTR InstName R11
SYMATTR Value 1k
SYMBOL Opamps\\LT1013 384 0 R0
SYMATTR InstName U1
TEXT -192 568 Left 0 !.tran 0 10m 0 1u

Yeah That's just about what I have....
I used a much bigger C2. I figured the DC path has a 500ms time
constant
so the AC path should turn on at about the same frequency.

Thanks for the LTspice circuit BTW.

George H.
 
J

josephkk

Jan 1, 1970
0
RE: DC feedback... I was a bit lazy and just put the words
"to invertng input"<----

See above for DC feed back.

Yeah That's just about what I have....
I used a much bigger C2. I figured the DC path has a 500ms time
constant
so the AC path should turn on at about the same frequency.

Thanks for the LTspice circuit BTW.

George H.

Ok. Similar to the LTSpice circuit i posted. It is a useful tool, but
the very incomplete libraries (even of LTC parts) can be very frustrating.

?-)
 
D

Don Lancaster

Jan 1, 1970
0
No, it can be a good idea in voltage references! :)

You can often use the (boosted) output to source the drive to
the reference. So it is almost completely immune to supply variations.


Here's the original schematic...

< http://www.repeater-builder.com/tech-info/dtmf/bell-dtmf.html >

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com
 
J

josephkk

Jan 1, 1970
0
That goddamn Greek mu again?

I guess i will have to check the settings again. I thought i had all
copies set to use "u" for comparability.

?-/
 
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