How can you enhance Sijosae splitter precision without a trimmer?...

[server]

On Tue, 15 Dec 2020 11:58:38 GMT, Steve Wilson <spam@me.com> wrote:

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/14/20 10:32 PM, Don wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 12/14/20 8:43 PM, Dave Platt wrote:
In article <ihuftfh1slneffn78vtj5lpljd5b6bmvsi@4ax.com>,
John Larkin <xx@yy.com> wrote:

We don\'t know his actual \"modded\" circuit, but the Sijosae
splitters that show up in google searches look awfully soft and
sloppy.

One site I read described them as significantly better than a
simple resistive divider, but significantly worse than any other
buffered circuit they described (typically op-amp-based).
Price-wise that\'s about how they fall, too. I guess you get what
you pay for.

Unless the supplies are super accurate, I can\'t see much virtue in
a precise splitter. Downstream circuits shouldn\'t care much.

We don\'t know the requirements of the downstream circuits, either -
why precision seemed to be called for.



A resistive divider and a TCA0372.

Unfortunately, there\'s nary a TCA0372 available in my parts bin. But,
there\'s a LM317, LM337, and a 3.3 V zener diode available, along with
a 19 VDC wall wart from the bone pile. Beings so many think the
Sijosae splitter stinks, it may behoove me to move on to an
adaptation of this circuit:

https://i.stack.imgur.com/kPjJF.jpg

Danke,


You can get a TCA0372 or L270 in a day, or wrap a class-B amp made
from an NPN + PNP complementary follower inside the feedback loop of a
741. Either would be a lot better than a crude class-AB splitter made
from two vregs.

Put a resistor from the bases to the emitters of the follower to take
the current at low load.

Cheers

Phil Hobbs

Nobody uses 741\'s any more.

Adding a resistor is not so simple. The basic circuit has a lot of
distortion. This would create havoc in a feedback circuit at high
frequency or at DC with transients in the load.

For low distortion at high frequency, or fast load transients at DC, a
full complimentary driver looks much better.

Version 4
SHEET 1 1608 1700
WIRE 384 80 368 80
WIRE 512 80 464 80
WIRE 592 80 512 80
WIRE 704 80 592 80
WIRE 592 96 592 80
WIRE 704 96 704 80
WIRE 368 144 368 80
WIRE 528 144 368 144
WIRE 224 192 160 192
WIRE 256 192 224 192
WIRE 304 192 256 192
WIRE 704 192 704 176
WIRE 160 208 160 192
WIRE 480 240 368 240
WIRE 592 256 592 192
WIRE 672 256 592 256
WIRE 784 256 672 256
WIRE 512 272 512 80
WIRE 512 272 368 272
WIRE 784 272 784 256
WIRE 160 304 160 288
WIRE 256 320 256 192
WIRE 304 320 256 320
WIRE 592 320 592 256
WIRE 528 368 368 368
WIRE 784 368 784 352
WIRE 368 448 368 368
WIRE 384 448 368 448
WIRE 480 448 480 240
WIRE 480 448 464 448
WIRE 592 448 592 416
WIRE 592 448 480 448
WIRE 592 464 592 448
WIRE 592 560 592 544
FLAG 160 304 0
FLAG 592 560 0
FLAG 704 192 0
FLAG 784 368 0
FLAG 224 192 Vin
FLAG 672 256 Vout
SYMBOL voltage 160 192 R0
WINDOW 3 -53 150 Left 2
WINDOW 123 24 38 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value SINE(0 2 1e6)
SYMATTR Value2 AC 1
SYMATTR InstName V1
SYMBOL npn 528 96 R0
SYMATTR InstName Q1
SYMATTR Value 2N2222
SYMBOL pnp 528 416 M180
SYMATTR InstName Q2
SYMATTR Value 2N2907
SYMBOL voltage 592 560 R180
WINDOW 0 24 96 Left 2
WINDOW 3 24 16 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value {VCC}
SYMBOL voltage 704 80 R0
WINDOW 0 24 96 Left 2
WINDOW 3 24 16 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V3
SYMATTR Value {VCC}
SYMBOL res 768 256 R0
SYMATTR InstName R1
SYMATTR Value 50
SYMBOL pnp 304 240 M180
SYMATTR InstName Q3
SYMATTR Value 2N2907
SYMBOL npn 304 272 R0
SYMATTR InstName Q4
SYMATTR Value 2N2222
SYMBOL res 480 432 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 330
SYMBOL res 480 64 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 330
TEXT 376 -24 Left 2 ;\'Complimentary Driver / Follower
TEXT 376 0 Left 2 !.tran 0 2u 0
TEXT 552 0 Left 2 !.param VCC = 12

That will oscillate, until it blows up.



--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

 

[Phil Hobbs]

On 12/15/20 8:24 AM, Phil Hobbs wrote:

On 12/15/20 6:58 AM, Steve Wilson wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/14/20 10:32 PM, Don wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 12/14/20 8:43 PM, Dave Platt wrote:
In article <ihuftfh1slneffn78vtj5lpljd5b6bmvsi@4ax.com>,
John Larkin  <xx@yy.com> wrote:

We don\'t know his actual \"modded\" circuit, but the Sijosae
splitters that show up in google searches look awfully soft and
sloppy.

One site I read described them as significantly better than a
simple resistive divider, but significantly worse than any other
buffered circuit they described (typically op-amp-based).
Price-wise that\'s about how they fall, too.  I guess you get what
you pay for.

Unless the supplies are super accurate, I can\'t see much virtue in
a precise splitter. Downstream circuits shouldn\'t care much.

We don\'t know the requirements of the downstream circuits, either -
why precision seemed to be called for.



A resistive divider and a TCA0372.

Unfortunately, there\'s nary a TCA0372 available in my parts bin. But,
there\'s a LM317, LM337, and a 3.3 V zener diode available, along with
a 19 VDC wall wart from the bone pile. Beings so many think the
Sijosae splitter stinks, it may behoove me to move on to an
adaptation of this circuit:

      https://i.stack.imgur.com/kPjJF.jpg

Danke,


You can get a TCA0372 or L270 in a day, or wrap a class-B amp made
from an NPN + PNP complementary follower inside the feedback loop of a
741. Either would be a lot better than a crude class-AB splitter made
from two vregs.

Put a resistor from the bases to the emitters of the follower to take
the current at low load.
Cheers
Phil Hobbs

Nobody uses 741\'s any more.
Of course they don\'t--I was teasing Don about his fixation with his
junkbox.

Adding a resistor is not so simple. The basic circuit has a lot of
distortion. This would create havoc in a feedback circuit at high
frequency or at DC with transients in the load

Which is why you put a BFC on it, the way you would any regulator,
including the TCA0372.

Like this.

Cheers

Phil Hobbs
------------
Version 4
SHEET 1 1344 1808
WIRE 80 -80 -112 -80
WIRE 576 -80 80 -80
WIRE 880 -80 576 -80
WIRE 880 -48 880 -80
WIRE 800 -32 32 -32
WIRE 576 0 576 -80
WIRE -112 16 -112 -80
WIRE 512 48 464 48
WIRE 880 48 880 32
WIRE 80 96 80 -80
WIRE 32 112 32 -32
WIRE 48 112 32 112
WIRE 368 128 112 128
WIRE 464 128 464 48
WIRE 464 128 448 128
WIRE 480 128 464 128
WIRE 576 128 576 96
WIRE 576 128 560 128
WIRE -112 144 -112 96
WIRE 48 144 -112 144
WIRE 576 160 576 128
WIRE 592 160 576 160
WIRE 720 160 672 160
WIRE 800 160 800 -32
WIRE 800 160 720 160
WIRE 848 160 800 160
WIRE 864 160 848 160
WIRE -112 176 -112 144
WIRE 576 176 576 160
WIRE 864 176 864 160
WIRE 720 208 720 160
WIRE 464 224 464 128
WIRE 512 224 464 224
WIRE -112 288 -112 256
WIRE -48 288 -112 288
WIRE 80 288 80 160
WIRE 80 288 -48 288
WIRE 864 288 864 256
WIRE 576 304 576 272
WIRE 592 304 576 304
WIRE 976 304 960 304
WIRE 976 320 976 304
WIRE -112 352 -112 288
WIRE 720 368 720 352
WIRE 976 432 976 400
WIRE -112 448 -112 432
FLAG 880 48 0
FLAG -112 448 0
FLAG 720 368 0
FLAG 864 288 0
FLAG 848 160 split
FLAG 976 432 0
FLAG 960 304 split
FLAG 880 -80 V+
FLAG -48 288 V-
FLAG 592 304 V-
SYMBOL voltage 880 -64 R0
SYMATTR InstName V1
SYMATTR Value 6
SYMBOL res -128 0 R0
SYMATTR InstName R1
SYMATTR Value 5k
SYMBOL res -128 160 R0
SYMATTR InstName R2
SYMATTR Value 5k
SYMBOL npn 512 0 R0
WINDOW 0 67 20 Left 2
WINDOW 3 35 58 Left 2
SYMATTR InstName Q1
SYMATTR Value 2N4401
SYMBOL pnp 512 272 M180
WINDOW 0 39 41 Left 2
WINDOW 3 80 17 Left 2
SYMATTR InstName Q2
SYMATTR Value 2N4403
SYMBOL res 576 112 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 100
SYMBOL cap 704 208 R0
SYMATTR InstName C1
SYMATTR Value 100u
SYMBOL current 864 176 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName I1
SYMATTR Value PULSE(-50m 50m 1m 50n 50n 5u 10u)
SYMBOL Opamps\\\\opamp2 80 64 R0
WINDOW 3 19 134 Left 2
SYMATTR InstName U1
SYMATTR Value TL084
SYMBOL voltage -112 336 R0
SYMATTR InstName V2
SYMATTR Value -6
SYMBOL res 704 256 R0
SYMATTR InstName R5
SYMATTR Value 47m
SYMBOL res 464 112 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R6
SYMATTR Value 1m
SYMBOL current 976 320 R0
WINDOW 3 -283 177 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName I2
SYMATTR Value PULSE(-50m 50m 10m 50n 50n 5m 10m)
SYMBOL res 688 144 R90
WINDOW 0 -12 56 VBottom 2
WINDOW 3 38 55 VTop 2
SYMATTR InstName R8
SYMATTR Value 1m
TEXT 520 464 Left 2 !.tran 30m
TEXT -96 480 Left 2 !*
TEXT -96 490 Left 2 !*$
TEXT -96 500 Left 2 !* TL084 OP AMP \"MACROMODEL\" SUBCIRCUIT
TEXT -96 510 Left 2 !* CREATED with PARTS REL 4.01 ON 06/16/89
TEXT -96 520 Left 2 !* (REV N/A) SUPPLY VOLTAGE: +/-15V
TEXT -96 530 Left 2 !* CONNECTIONS: NON-INVERTING INPUT
TEXT -96 540 Left 2 !* | INVERTING INPUT
TEXT -96 550 Left 2 !* | | POSITIVE POWER SUPPLY
TEXT -96 560 Left 2 !* | | | NEGATIVE POWER SUPPLY
TEXT -96 570 Left 2 !* | | | | OUTPUT
TEXT -96 580 Left 2 !* | | | | |
TEXT -96 590 Left 2 !.SUBCKT TL084 1 2 3 4 5
TEXT -96 600 Left 2 !*
TEXT -96 610 Left 2 ! C1 11 12 3.498E-12
TEXT -96 620 Left 2 ! C2 6 7 15.00E-12
TEXT -96 630 Left 2 ! DC 5 53 DX
TEXT -96 640 Left 2 ! DE 54 5 DX
TEXT -96 650 Left 2 ! DLP 90 91 DX
TEXT -96 660 Left 2 ! DLN 92 90 DX
TEXT -96 670 Left 2 ! DP 4 3 DX
TEXT -96 680 Left 2 ! EGND 99 0 POLY(2) (3,0) (4,0) 0 .5 .5
TEXT -96 690 Left 2 !FB 7 99 POLY(5) VB VC VE VLP VLN 0 4.715E6 -5E6 5E6
TEXT -96 700 Left 2 !
TEXT -96 710 Left 2 ! GA 6 0 11 12 282.8E-6
TEXT -96 720 Left 2 ! GCM 0 6 10 99 8.942E-9
TEXT -96 730 Left 2 ! ISS 3 10 DC 195.0E-6
TEXT -96 740 Left 2 ! HLIM 90 0 VLIM 1K
TEXT -96 750 Left 2 ! J1 11 2 10 JX
TEXT -96 760 Left 2 ! J2 12 1 10 JX
TEXT -96 770 Left 2 ! R2 6 9 100.0E3
TEXT -96 780 Left 2 ! RD1 4 11 3.536E3
TEXT -96 790 Left 2 ! RD2 4 12 3.536E3
TEXT -96 800 Left 2 ! RO1 8 5 150
TEXT -96 810 Left 2 ! RO2 7 99 150
TEXT -96 820 Left 2 ! RP 3 4 2.143E3
TEXT -96 830 Left 2 ! RSS 10 99 1.026E6
TEXT -96 840 Left 2 ! VB 9 0 DC 0
TEXT -96 850 Left 2 ! VC 3 53 DC 2.200
TEXT -96 860 Left 2 ! VE 54 4 DC 2.200
TEXT -96 870 Left 2 ! VLIM 7 8 DC 0
TEXT -96 880 Left 2 ! VLP 91 0 DC 25
TEXT -96 890 Left 2 ! VLN 0 92 DC 25
TEXT -96 900 Left 2 !.MODEL DX D(IS=800.0E-18)
TEXT -96 910 Left 2 !.MODEL JX PJF(IS=15.00E-12 BETA=270.1E-6 VTO=-1)
TEXT -96 920 Left 2 !.ENDS




--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[server]

On Tue, 15 Dec 2020 08:24:46 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 6:58 AM, Steve Wilson wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/14/20 10:32 PM, Don wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 12/14/20 8:43 PM, Dave Platt wrote:
In article <ihuftfh1slneffn78vtj5lpljd5b6bmvsi@4ax.com>,
John Larkin <xx@yy.com> wrote:

We don\'t know his actual \"modded\" circuit, but the Sijosae
splitters that show up in google searches look awfully soft and
sloppy.

One site I read described them as significantly better than a
simple resistive divider, but significantly worse than any other
buffered circuit they described (typically op-amp-based).
Price-wise that\'s about how they fall, too. I guess you get what
you pay for.

Unless the supplies are super accurate, I can\'t see much virtue in
a precise splitter. Downstream circuits shouldn\'t care much.

We don\'t know the requirements of the downstream circuits, either -
why precision seemed to be called for.



A resistive divider and a TCA0372.

Unfortunately, there\'s nary a TCA0372 available in my parts bin. But,
there\'s a LM317, LM337, and a 3.3 V zener diode available, along with
a 19 VDC wall wart from the bone pile. Beings so many think the
Sijosae splitter stinks, it may behoove me to move on to an
adaptation of this circuit:

https://i.stack.imgur.com/kPjJF.jpg

Danke,


You can get a TCA0372 or L270 in a day, or wrap a class-B amp made
from an NPN + PNP complementary follower inside the feedback loop of a
741. Either would be a lot better than a crude class-AB splitter made
from two vregs.

Put a resistor from the bases to the emitters of the follower to take
the current at low load.

Cheers

Phil Hobbs

Nobody uses 741\'s any more.

Of course they don\'t--I was teasing Don about his fixation with his junkbox.

Adding a resistor is not so simple. The basic circuit has a lot of
distortion. This would create havoc in a feedback circuit at high
frequency or at DC with transients in the load

Which is why you put a BFC on it, the way you would any regulator,
including the TCA0372.

Cheers

Phil Hobbs

TCA0372 is stable as a follower with a big aluminum or polymer or
tantalum to ground. A 1-ohm series resistor can be included for the
skeptical.

I love that part. I use it as a voltage regulator, a fan controller,
or a relay driver. Sometimes both.



--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

 

[Phil Hobbs]

On 12/15/20 11:07 AM, jlarkin@highlandsniptechnology.com wrote:

On Tue, 15 Dec 2020 08:24:46 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 6:58 AM, Steve Wilson wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/14/20 10:32 PM, Don wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 12/14/20 8:43 PM, Dave Platt wrote:
In article <ihuftfh1slneffn78vtj5lpljd5b6bmvsi@4ax.com>,
John Larkin <xx@yy.com> wrote:

We don\'t know his actual \"modded\" circuit, but the Sijosae
splitters that show up in google searches look awfully soft and
sloppy.

One site I read described them as significantly better than a
simple resistive divider, but significantly worse than any other
buffered circuit they described (typically op-amp-based).
Price-wise that\'s about how they fall, too. I guess you get what
you pay for.

Unless the supplies are super accurate, I can\'t see much virtue in
a precise splitter. Downstream circuits shouldn\'t care much.

We don\'t know the requirements of the downstream circuits, either -
why precision seemed to be called for.



A resistive divider and a TCA0372.

Unfortunately, there\'s nary a TCA0372 available in my parts bin. But,
there\'s a LM317, LM337, and a 3.3 V zener diode available, along with
a 19 VDC wall wart from the bone pile. Beings so many think the
Sijosae splitter stinks, it may behoove me to move on to an
adaptation of this circuit:

https://i.stack.imgur.com/kPjJF.jpg

Danke,


You can get a TCA0372 or L270 in a day, or wrap a class-B amp made
from an NPN + PNP complementary follower inside the feedback loop of a
741. Either would be a lot better than a crude class-AB splitter made
from two vregs.

Put a resistor from the bases to the emitters of the follower to take
the current at low load.

Cheers

Phil Hobbs

Nobody uses 741\'s any more.

Of course they don\'t--I was teasing Don about his fixation with his junkbox.

Adding a resistor is not so simple. The basic circuit has a lot of
distortion. This would create havoc in a feedback circuit at high
frequency or at DC with transients in the load

Which is why you put a BFC on it, the way you would any regulator,
including the TCA0372.

TCA0372 is stable as a follower with a big aluminum or polymer or
tantalum to ground. A 1-ohm series resistor can be included for the
skeptical.
You can verify that by scoping the supply current, of course.

I love that part. I use it as a voltage regulator, a fan controller,
or a relay driver. Sometimes both.

Yeah, I\'m fond of it too. I usually use it for floating grounds of one
sort or another, e.g. biasing some fast front end made with a +-5V op
amp up at a higher voltage. Supplies are a bit iffy, but the L272 is
very similar except for crummy max supplies, 28V vs. 40V. Not
pin-compatible, unfortunately.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[server]

On Tue, 15 Dec 2020 12:20:39 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 11:07 AM, jlarkin@highlandsniptechnology.com wrote:
On Tue, 15 Dec 2020 08:24:46 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 6:58 AM, Steve Wilson wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/14/20 10:32 PM, Don wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 12/14/20 8:43 PM, Dave Platt wrote:
In article <ihuftfh1slneffn78vtj5lpljd5b6bmvsi@4ax.com>,
John Larkin <xx@yy.com> wrote:

We don\'t know his actual \"modded\" circuit, but the Sijosae
splitters that show up in google searches look awfully soft and
sloppy.

One site I read described them as significantly better than a
simple resistive divider, but significantly worse than any other
buffered circuit they described (typically op-amp-based).
Price-wise that\'s about how they fall, too. I guess you get what
you pay for.

Unless the supplies are super accurate, I can\'t see much virtue in
a precise splitter. Downstream circuits shouldn\'t care much.

We don\'t know the requirements of the downstream circuits, either -
why precision seemed to be called for.



A resistive divider and a TCA0372.

Unfortunately, there\'s nary a TCA0372 available in my parts bin. But,
there\'s a LM317, LM337, and a 3.3 V zener diode available, along with
a 19 VDC wall wart from the bone pile. Beings so many think the
Sijosae splitter stinks, it may behoove me to move on to an
adaptation of this circuit:

https://i.stack.imgur.com/kPjJF.jpg

Danke,


You can get a TCA0372 or L270 in a day, or wrap a class-B amp made
from an NPN + PNP complementary follower inside the feedback loop of a
741. Either would be a lot better than a crude class-AB splitter made
from two vregs.

Put a resistor from the bases to the emitters of the follower to take
the current at low load.

Cheers

Phil Hobbs

Nobody uses 741\'s any more.

Of course they don\'t--I was teasing Don about his fixation with his junkbox.

Adding a resistor is not so simple. The basic circuit has a lot of
distortion. This would create havoc in a feedback circuit at high
frequency or at DC with transients in the load

Which is why you put a BFC on it, the way you would any regulator,
including the TCA0372.

TCA0372 is stable as a follower with a big aluminum or polymer or
tantalum to ground. A 1-ohm series resistor can be included for the
skeptical.
You can verify that by scoping the supply current, of course.

I love that part. I use it as a voltage regulator, a fan controller,
or a relay driver. Sometimes both.

Yeah, I\'m fond of it too. I usually use it for floating grounds of one
sort or another, e.g. biasing some fast front end made with a +-5V op
amp up at a higher voltage. Supplies are a bit iffy, but the L272 is
very similar except for crummy max supplies, 28V vs. 40V. Not
pin-compatible, unfortunately.

Cheers

Phil Hobbs

Here are a few notes. There is some question as to whether the thermal
shutdown is really protective at higher supply voltages.

https://www.dropbox.com/sh/v6kzsu7349nr288/AAB5odutGRtDi1VnOYiA1MIVa?dl=0

I think ST or someone makes an equivalent part.





--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

 

[Steve Wilson]

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 6:58 AM, Steve Wilson wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/14/20 10:32 PM, Don wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 12/14/20 8:43 PM, Dave Platt wrote:
In article <ihuftfh1slneffn78vtj5lpljd5b6bmvsi@4ax.com>,
John Larkin <xx@yy.com> wrote:

We don\'t know his actual \"modded\" circuit, but the Sijosae
splitters that show up in google searches look awfully soft and
sloppy.

One site I read described them as significantly better than a
simple resistive divider, but significantly worse than any other
buffered circuit they described (typically op-amp-based).
Price-wise that\'s about how they fall, too. I guess you get what
you pay for.

Unless the supplies are super accurate, I can\'t see much virtue
in a precise splitter. Downstream circuits shouldn\'t care much.

We don\'t know the requirements of the downstream circuits, either
- why precision seemed to be called for.



A resistive divider and a TCA0372.

Unfortunately, there\'s nary a TCA0372 available in my parts bin.
But, there\'s a LM317, LM337, and a 3.3 V zener diode available,
along with a 19 VDC wall wart from the bone pile. Beings so many
think the Sijosae splitter stinks, it may behoove me to move on to
an adaptation of this circuit:

https://i.stack.imgur.com/kPjJF.jpg

Danke,


You can get a TCA0372 or L270 in a day, or wrap a class-B amp made
from an NPN + PNP complementary follower inside the feedback loop of
a 741. Either would be a lot better than a crude class-AB splitter
made from two vregs.

Put a resistor from the bases to the emitters of the follower to
take the current at low load.

Cheers

Phil Hobbs

Nobody uses 741\'s any more.

Of course they don\'t--I was teasing Don about his fixation with his
junkbox.

Adding a resistor is not so simple. The basic circuit has a lot of
distortion. This would create havoc in a feedback circuit at high
frequency or at DC with transients in the load

Which is why you put a BFC on it, the way you would any regulator,
including the TCA0372.

What\'s a BFC?

Cheers

Phil Hobbs

--
The best designs occur in the theta state. - sw

 

[Steve Wilson]

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 8:24 AM, Phil Hobbs wrote:
On 12/15/20 6:58 AM, Steve Wilson wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/14/20 10:32 PM, Don wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 12/14/20 8:43 PM, Dave Platt wrote:
In article <ihuftfh1slneffn78vtj5lpljd5b6bmvsi@4ax.com>,
John Larkin  <xx@yy.com> wrote:

We don\'t know his actual \"modded\" circuit, but the Sijosae
splitters that show up in google searches look awfully soft and
sloppy.

One site I read described them as significantly better than a
simple resistive divider, but significantly worse than any other
buffered circuit they described (typically op-amp-based).
Price-wise that\'s about how they fall, too.  I guess you get
what you pay for.

Unless the supplies are super accurate, I can\'t see much virtue
in a precise splitter. Downstream circuits shouldn\'t care much.

We don\'t know the requirements of the downstream circuits,
either - why precision seemed to be called for.



A resistive divider and a TCA0372.

Unfortunately, there\'s nary a TCA0372 available in my parts bin.
But, there\'s a LM317, LM337, and a 3.3 V zener diode available,
along with a 19 VDC wall wart from the bone pile. Beings so many
think the Sijosae splitter stinks, it may behoove me to move on to
an adaptation of this circuit:

      https://i.stack.imgur.com/kPjJF.jpg

Danke,


You can get a TCA0372 or L270 in a day, or wrap a class-B amp made
from an NPN + PNP complementary follower inside the feedback loop
of a 741. Either would be a lot better than a crude class-AB
splitter made from two vregs.

Put a resistor from the bases to the emitters of the follower to
take the current at low load.
Cheers
Phil Hobbs

Nobody uses 741\'s any more.
Of course they don\'t--I was teasing Don about his fixation with his
junkbox.

Adding a resistor is not so simple. The basic circuit has a lot of
distortion. This would create havoc in a feedback circuit at high
frequency or at DC with transients in the load

Which is why you put a BFC on it, the way you would any regulator,
including the TCA0372.

Like this.

Cheers

Phil Hobbs

[...]

One of the worst LTspice circuits on the web. You should be an example to
others instead of an example of poor design:

- no labels on nodes. The node number can change if you add or modify the
crcuit. Any plots will point to a different node making it impossible to
decipher the circuit.

- the 1m resistors serve no purpose.

- what is the point of adding pulsed square wave current loads at 100KHz
and 100Hz. This does not allow you to evaluate the distortion in the
follower.

- a continuous square wave load does not represent a transient. There is
no steady-state DC output.

- the model statements overlap and are impossible to read.

There is still no explanation of BFC.



--
The best designs occur in the theta state. - sw

 

[Steve Wilson]

jlarkin@highlandsniptechnology.com wrote:

TCA0372 is stable as a follower with a big aluminum or polymer or
tantalum to ground. A 1-ohm series resistor can be included for the
skeptical.

The datasheet only goes to 2nF. A big capacitor would imply no phase
margin. See Figure 5. Phase Margin versus Output Load Capacitance

https://datasheet.octopart.com/TCA0372DWG-ON-Semiconductor-datasheet-
139012425.pdf


--
The best designs occur in the theta state. - sw

 

[Phil Hobbs]

On 12/15/20 12:54 PM, jlarkin@highlandsniptechnology.com wrote:

On Tue, 15 Dec 2020 12:20:39 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 11:07 AM, jlarkin@highlandsniptechnology.com wrote:
On Tue, 15 Dec 2020 08:24:46 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 6:58 AM, Steve Wilson wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/14/20 10:32 PM, Don wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 12/14/20 8:43 PM, Dave Platt wrote:
In article <ihuftfh1slneffn78vtj5lpljd5b6bmvsi@4ax.com>,
John Larkin <xx@yy.com> wrote:

We don\'t know his actual \"modded\" circuit, but the Sijosae
splitters that show up in google searches look awfully soft and
sloppy.

One site I read described them as significantly better than a
simple resistive divider, but significantly worse than any other
buffered circuit they described (typically op-amp-based).
Price-wise that\'s about how they fall, too. I guess you get what
you pay for.

Unless the supplies are super accurate, I can\'t see much virtue in
a precise splitter. Downstream circuits shouldn\'t care much.

We don\'t know the requirements of the downstream circuits, either -
why precision seemed to be called for.



A resistive divider and a TCA0372.

Unfortunately, there\'s nary a TCA0372 available in my parts bin. But,
there\'s a LM317, LM337, and a 3.3 V zener diode available, along with
a 19 VDC wall wart from the bone pile. Beings so many think the
Sijosae splitter stinks, it may behoove me to move on to an
adaptation of this circuit:

https://i.stack.imgur.com/kPjJF.jpg

Danke,


You can get a TCA0372 or L270 in a day, or wrap a class-B amp made
from an NPN + PNP complementary follower inside the feedback loop of a
741. Either would be a lot better than a crude class-AB splitter made
from two vregs.

Put a resistor from the bases to the emitters of the follower to take
the current at low load.

Cheers

Phil Hobbs

Nobody uses 741\'s any more.

Of course they don\'t--I was teasing Don about his fixation with his junkbox.

Adding a resistor is not so simple. The basic circuit has a lot of
distortion. This would create havoc in a feedback circuit at high
frequency or at DC with transients in the load

Which is why you put a BFC on it, the way you would any regulator,
including the TCA0372.

TCA0372 is stable as a follower with a big aluminum or polymer or
tantalum to ground. A 1-ohm series resistor can be included for the
skeptical.
You can verify that by scoping the supply current, of course.

I love that part. I use it as a voltage regulator, a fan controller,
or a relay driver. Sometimes both.

Yeah, I\'m fond of it too. I usually use it for floating grounds of one
sort or another, e.g. biasing some fast front end made with a +-5V op
amp up at a higher voltage. Supplies are a bit iffy, but the L272 is
very similar except for crummy max supplies, 28V vs. 40V. Not
pin-compatible, unfortunately.

Here are a few notes. There is some question as to whether the thermal
shutdown is really protective at higher supply voltages.

https://www.dropbox.com/sh/v6kzsu7349nr288/AAB5odutGRtDi1VnOYiA1MIVa?dl=0

Thanks. Looks about like my experience with it.

I think ST or someone makes an equivalent part.

Yeah, ST makes the L272, a lower-voltage near-equivalent.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Steve Wilson]

jlarkin@highlandsniptechnology.com wrote:

> That will oscillate, until it blows up.

What gives you that idea?

I have been using it since the late 1960\'s. It has no tendency to oscillate
in pure analog or digital circuits. It is wideband, low distortion, and
stable as a rock.



--
The best designs occur in the theta state. - sw

 

[John Larkin]

On Tue, 15 Dec 2020 20:17:12 GMT, Steve Wilson <spam@me.com> wrote:

jlarkin@highlandsniptechnology.com wrote:

TCA0372 is stable as a follower with a big aluminum or polymer or
tantalum to ground. A 1-ohm series resistor can be included for the
skeptical.

The datasheet only goes to 2nF. A big capacitor would imply no phase
margin. See Figure 5. Phase Margin versus Output Load Capacitance

https://datasheet.octopart.com/TCA0372DWG-ON-Semiconductor-datasheet-
139012425.pdf

That\'s why I tested it.

 

[whit3rd]

On Monday, December 14, 2020 at 5:08:02 PM UTC-8, Don wrote:

... a Sijosae splitter seems
unpopular, give me an alternative, which works with parts typically
found in most parts drawers. The Sijosae splitter show below at the link
uses such parts:

https://tangentsoft.net/elec/bitmaps/vgrounds/sijosae.png

A virtual ground circuit to split a wall wart between positive and
negative rails is what\'s needed.

One would want to identify the weaknesses and improve on them; the
\'wall wart\' might have transients, and balance of the input capacitor values
is required to keep those transients off the output. But, the output impedance
as shown is five or ten ohms (and changes slightly if there\'s a bias current at
the GND pin, because one of the output transistors turns off). So, there\'s limited
ability to handle a ground-pin transient currents without some ground bounce.

In terms of the overall (wallwart with two wire cord feeding split power at target)
problem, one can find a 48V wallwart, and use a telecom-style converter
at the target to get symmetric plus/minus power. It\'s a tad more cost, but
easy with off-the-shelf gizmos, and I got a load of +/- 12V, +5V units at
surplus prices some years ago...
As a bonus, such converters are useful without the Class II inputs, you can ground
any pin at will (so the same converter can be used for -24V or +17V...).

 

[John Larkin]

On Tue, 15 Dec 2020 20:26:01 GMT, Steve Wilson <spam@me.com> wrote:

jlarkin@highlandsniptechnology.com wrote:

That will oscillate, until it blows up.

What gives you that idea?

I have been using it since the late 1960\'s. It has no tendency to oscillate
in pure analog or digital circuits. It is wideband, low distortion, and
stable as a rock.

2N2222 followers are notorious for oscillating. That circuit is almost
frying the transistors, and thermal runaway will finish the job.

 

[Phil Hobbs]

On 12/15/20 3:31 PM, John Larkin wrote:

On Tue, 15 Dec 2020 20:17:12 GMT, Steve Wilson <spam@me.com> wrote:

jlarkin@highlandsniptechnology.com wrote:

TCA0372 is stable as a follower with a big aluminum or polymer or
tantalum to ground. A 1-ohm series resistor can be included for the
skeptical.

The datasheet only goes to 2nF. A big capacitor would imply no phase
margin. See Figure 5. Phase Margin versus Output Load Capacitance

https://datasheet.octopart.com/TCA0372DWG-ON-Semiconductor-datasheet-
139012425.pdf

That\'s why I tested it.

The issue only arises when the poles are too close together. By making
the output pole into a lead/lag network (100 uF with ~0.05 ohms ESR) the
overall feedback loop becomes stable. It\'s the same way you stabilize a
switcher that doesn\'t like all-ceramic output caps.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[John Larkin]

On Tue, 15 Dec 2020 15:40:23 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 3:31 PM, John Larkin wrote:
On Tue, 15 Dec 2020 20:17:12 GMT, Steve Wilson <spam@me.com> wrote:

jlarkin@highlandsniptechnology.com wrote:

TCA0372 is stable as a follower with a big aluminum or polymer or
tantalum to ground. A 1-ohm series resistor can be included for the
skeptical.

The datasheet only goes to 2nF. A big capacitor would imply no phase
margin. See Figure 5. Phase Margin versus Output Load Capacitance

https://datasheet.octopart.com/TCA0372DWG-ON-Semiconductor-datasheet-
139012425.pdf

That\'s why I tested it.


The issue only arises when the poles are too close together. By making
the output pole into a lead/lag network (100 uF with ~0.05 ohms ESR) the
overall feedback loop becomes stable. It\'s the same way you stabilize a
switcher that doesn\'t like all-ceramic output caps.

Cheers

Phil Hobbs

That\'s the Jim Williams Stabilization Technique: add big caps until it
stops oscillating.

Lots of opamps are stable with a big modest-ESR cap to ground. Many
are stable with a lot of ceramics to ground too. But the only way to
be sure is to test them.

Some opamps are pretty good comparators, ditto.

 

[Phil Hobbs]

On 12/15/20 3:07 PM, Steve Wilson wrote:

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 8:24 AM, Phil Hobbs wrote:
On 12/15/20 6:58 AM, Steve Wilson wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/14/20 10:32 PM, Don wrote:
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
On 12/14/20 8:43 PM, Dave Platt wrote:
In article <ihuftfh1slneffn78vtj5lpljd5b6bmvsi@4ax.com>,
John Larkin  <xx@yy.com> wrote:

We don\'t know his actual \"modded\" circuit, but the Sijosae
splitters that show up in google searches look awfully soft and
sloppy.

One site I read described them as significantly better than a
simple resistive divider, but significantly worse than any other
buffered circuit they described (typically op-amp-based).
Price-wise that\'s about how they fall, too.  I guess you get
what you pay for.

Unless the supplies are super accurate, I can\'t see much virtue
in a precise splitter. Downstream circuits shouldn\'t care much.

We don\'t know the requirements of the downstream circuits,
either - why precision seemed to be called for.



A resistive divider and a TCA0372.

Unfortunately, there\'s nary a TCA0372 available in my parts bin.
But, there\'s a LM317, LM337, and a 3.3 V zener diode available,
along with a 19 VDC wall wart from the bone pile. Beings so many
think the Sijosae splitter stinks, it may behoove me to move on to
an adaptation of this circuit:

      https://i.stack.imgur.com/kPjJF.jpg

Danke,


You can get a TCA0372 or L270 in a day, or wrap a class-B amp made
from an NPN + PNP complementary follower inside the feedback loop
of a 741. Either would be a lot better than a crude class-AB
splitter made from two vregs.

Put a resistor from the bases to the emitters of the follower to
take the current at low load.
Cheers
Phil Hobbs

Nobody uses 741\'s any more.
Of course they don\'t--I was teasing Don about his fixation with his
junkbox.

Adding a resistor is not so simple. The basic circuit has a lot of
distortion. This would create havoc in a feedback circuit at high
frequency or at DC with transients in the load

Which is why you put a BFC on it, the way you would any regulator,
including the TCA0372.

Like this.

Cheers

Phil Hobbs

[...]

One of the worst LTspice circuits on the web. You should be an example to
others instead of an example of poor design:

- no labels on nodes. The node number can change if you add or modify the
crcuit. Any plots will point to a different node making it impossible to
decipher the circuit.

- the 1m resistors serve no purpose.

- what is the point of adding pulsed square wave current loads at 100KHz
and 100Hz. This does not allow you to evaluate the distortion in the
follower.

- a continuous square wave load does not represent a transient. There is
no steady-state DC output.

- the model statements overlap and are impossible to read.

There is still no explanation of BFC.

Oh, come on.

0. The circuit is trivial, so I really don\'t expect anybody to do much
with my version. Its primary purpose is to show that your worries about
distortion and oscillation are misplaced. Node labels don\'t add
anything to that. I hereby release it under the Creative Commons
license, so you can add your own node labels if you like. Open source
hardware and so forth.

1. The 1 milliohm resistors are there to make it easy to plot the
currents. You can use zero-volt voltage sources for that, but they take
up too much screen space.

2. The follower\'s distortion is completely irrelevant, which is one of
the points I\'m making. What sane people expect in a rail splitter is
that it splits the rail without making any drama when you bang on it a
bit. This one copes with unpleasant loads with no issues. If I were
going to use it in real life, I\'d spend a lot more time on protection
circuitry, but the basic operation is fine.

3. You don\'t think that a load that switches between +-100 mA, in 100-mA
steps with 50-ns edges and a 1000:1 frequency range counts as a
transient? G\'wan.

4. If you really want to read a boring TL084 macromodel from over 30
years ago, you can open the .asc file with a text editor. I did it that
way so that people would know what it was, but without causing line wrap
problems or taking up all the screen space for the model.

I picked the TL084, 2N4401, and 2N4403 because if Don doesn\'t have
_those_ in his junkbox, it must be full of rusty bolts and springs
instead of electronics.

5. BFC stands for \"Big Fat Capacitor\", or something like that.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

On 12/15/20 4:03 PM, John Larkin wrote:

On Tue, 15 Dec 2020 15:40:23 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 3:31 PM, John Larkin wrote:
On Tue, 15 Dec 2020 20:17:12 GMT, Steve Wilson <spam@me.com> wrote:

jlarkin@highlandsniptechnology.com wrote:

TCA0372 is stable as a follower with a big aluminum or polymer or
tantalum to ground. A 1-ohm series resistor can be included for the
skeptical.

The datasheet only goes to 2nF. A big capacitor would imply no phase
margin. See Figure 5. Phase Margin versus Output Load Capacitance

https://datasheet.octopart.com/TCA0372DWG-ON-Semiconductor-datasheet-
139012425.pdf

That\'s why I tested it.


The issue only arises when the poles are too close together. By making
the output pole into a lead/lag network (100 uF with ~0.05 ohms ESR) the
overall feedback loop becomes stable. It\'s the same way you stabilize a
switcher that doesn\'t like all-ceramic output caps.


That\'s the Jim Williams Stabilization Technique: add big caps until it
stops oscillating.

Jim W was pretty smart about a lot of things. He did tend to use a
crapload of parts sometimes.

Lots of opamps are stable with a big modest-ESR cap to ground. Many
are stable with a lot of ceramics to ground too. But the only way to
be sure is to test them.

Scoping the supply rails to make sure there\'s no low-amplitude
oscillation. It takes a lot to make 100 uF of ceramic cap move very fast.

> Some opamps are pretty good comparators, ditto.

Just not the ones with the diodes across the inputs.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[John Larkin]

On Tue, 15 Dec 2020 16:50:20 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 4:03 PM, John Larkin wrote:
On Tue, 15 Dec 2020 15:40:23 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 12/15/20 3:31 PM, John Larkin wrote:
On Tue, 15 Dec 2020 20:17:12 GMT, Steve Wilson <spam@me.com> wrote:

jlarkin@highlandsniptechnology.com wrote:

TCA0372 is stable as a follower with a big aluminum or polymer or
tantalum to ground. A 1-ohm series resistor can be included for the
skeptical.

The datasheet only goes to 2nF. A big capacitor would imply no phase
margin. See Figure 5. Phase Margin versus Output Load Capacitance

https://datasheet.octopart.com/TCA0372DWG-ON-Semiconductor-datasheet-
139012425.pdf

That\'s why I tested it.


The issue only arises when the poles are too close together. By making
the output pole into a lead/lag network (100 uF with ~0.05 ohms ESR) the
overall feedback loop becomes stable. It\'s the same way you stabilize a
switcher that doesn\'t like all-ceramic output caps.


That\'s the Jim Williams Stabilization Technique: add big caps until it
stops oscillating.

Jim W was pretty smart about a lot of things. He did tend to use a
crapload of parts sometimes.

Oh, he was great. I met him a couple times at the Foothill Flea Market
(also sadly gone) and he was nice, interested, but very shy. His two
books are wonderful. But I think he never got an EE education, so he
ran more on instinct than theory.

Lots of opamps are stable with a big modest-ESR cap to ground. Many
are stable with a lot of ceramics to ground too. But the only way to
be sure is to test them.

Scoping the supply rails to make sure there\'s no low-amplitude
oscillation. It takes a lot to make 100 uF of ceramic cap move very fast.

Some opamps are pretty good comparators, ditto.

Just not the ones with the diodes across the inputs.

Ouch. Bad memories.

My current gumdrop, OPA197, is stable with a big cap and is a decent
RRIO comparator.

 

[amdx]

On 12/14/2020 8:42 PM, Phil Hobbs wrote:

On 12/14/20 8:43 PM, Dave Platt wrote:
In article <ihuftfh1slneffn78vtj5lpljd5b6bmvsi@4ax.com>,
John Larkin  <xx@yy.com> wrote:

We don\'t know his actual \"modded\" circuit, but the Sijosae splitters
that show up in google searches look awfully soft and sloppy.

One site I read described them as significantly better than a simple
resistive divider, but significantly worse than any other buffered
circuit they described (typically op-amp-based).  Price-wise that\'s
about how they fall, too.  I guess you get what you pay for.

Unless the supplies are super accurate, I can\'t see much virtue in a
precise splitter. Downstream circuits shouldn\'t care much.

We don\'t know the requirements of the downstream circuits, either -
why precision seemed to be called for.



A resistive divider and a TCA0372.

Cheers

Phil Hobbs

 For a breadboard... Use two wallwarts.

                                    Mikek


--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 

[Lasse Langwadt Christensen]

onsdag den 16. december 2020 kl. 00.14.17 UTC+1 skrev amdx:

On 12/14/2020 8:42 PM, Phil Hobbs wrote:
On 12/14/20 8:43 PM, Dave Platt wrote:
In article <ihuftfh1slneffn78...@4ax.com>,
John Larkin <x...@yy.com> wrote:

We don\'t know his actual \"modded\" circuit, but the Sijosae splitters
that show up in google searches look awfully soft and sloppy.

One site I read described them as significantly better than a simple
resistive divider, but significantly worse than any other buffered
circuit they described (typically op-amp-based). Price-wise that\'s
about how they fall, too. I guess you get what you pay for.

Unless the supplies are super accurate, I can\'t see much virtue in a
precise splitter. Downstream circuits shouldn\'t care much.

We don\'t know the requirements of the downstream circuits, either -
why precision seemed to be called for.



A resistive divider and a TCA0372.

Cheers

Phil Hobbs

For a breadboard... Use two wallwarts.

or find and old AC modem adapter and use a doubler