elektroda.net NewsGroups Forum Index - Electronics Design - line driver with automatic bias
Ban
Guest
Guest
Sat Aug 28, 2010 10:17 pm
features AB/operation of the output transistors with a bias current of 1.5mA
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |>
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |<
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
Ciao
Ban
Apricale, Italy
John Larkin
Guest
Guest
Sat Aug 28, 2010 10:50 pm
On Sat, 28 Aug 2010 23:17:43 +0200, "Ban" <bansuri_at_web.de> wrote:
Quote:
features AB/operation of the output transistors with a bias current of 1.5mA
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
Ciao
Ban
Apricale, Italy
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
Ciao
Ban
Apricale, Italy
OPA552?
John
Vladimir Vassilevsky
Guest
Guest
Sun Aug 29, 2010 1:02 am
Ban wrote:
Quote:
features AB/operation of the output transistors with a bias current of 1.5mA
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This one is simpler and better in all ways:
http://www.abvolt.com/misc/line_drv.jpg
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
John Larkin
Guest
Guest
Sun Aug 29, 2010 1:24 am
On Sat, 28 Aug 2010 19:02:30 -0500, Vladimir Vassilevsky
<nospam_at_nowhere.com> wrote:
Quote:
Ban wrote:
features AB/operation of the output transistors with a bias current of 1.5mA
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This one is simpler and better in all ways:
http://www.abvolt.com/misc/line_drv.jpg
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
This is nice and simple.
ftp://jjlarkin.lmi.net/OpampBoost.JPG
The resistor lets the opamp do some of the work at low level,
eliminating the deadband. Sort of. No thermal problems at all.
We could have a 500+ post thread about which "class" this is.
I don't understand Ban's circuit.
John
Jim Thompson
Guest
Guest
Sun Aug 29, 2010 2:12 am
On Sat, 28 Aug 2010 23:17:43 +0200, "Ban" <bansuri_at_web.de> wrote:
Quote:
features AB/operation of the output transistors with a bias current of 1.5mA
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
Ciao
Ban
Apricale, Italy
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
Ciao
Ban
Apricale, Italy
What a pile of crapola. Did you get that from Larkin ?
...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Spice is like a sports car...
Performance only as good as the person behind the wheel.
langwadt@fonz.dk
Guest
Guest
Sun Aug 29, 2010 2:31 am
On 28 Aug., 23:50, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
Quote:
On Sat, 28 Aug 2010 23:17:43 +0200, "Ban" <bans...@web.de> wrote:
features AB/operation of the output transistors with a bias current of 1..5mA
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
(created by AACircuit v1.28.6 beta 04/19/05www.tech-chat.de)
Ciao
Ban
Apricale, Italy
OPA552?
John
features AB/operation of the output transistors with a bias current of 1..5mA
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
(created by AACircuit v1.28.6 beta 04/19/05www.tech-chat.de)
Ciao
Ban
Apricale, Italy
OPA552?
John
yeh, not much point in cooking up something with and opamp and a bunch
of discretes, if the right opamp that can do it by itself
-Lasse
Vladimir Vassilevsky
Guest
Guest
Sun Aug 29, 2010 2:31 am
John Larkin wrote:
Quote:
On Sat, 28 Aug 2010 19:02:30 -0500, Vladimir Vassilevsky
nospam_at_nowhere.com> wrote:
Ban wrote:
features AB/operation of the output transistors with a bias current of 1.5mA
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This one is simpler and better in all ways:
http://www.abvolt.com/misc/line_drv.jpg
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
This is nice and simple.
ftp://jjlarkin.lmi.net/OpampBoost.JPG
nospam_at_nowhere.com> wrote:
Ban wrote:
features AB/operation of the output transistors with a bias current of 1.5mA
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This one is simpler and better in all ways:
http://www.abvolt.com/misc/line_drv.jpg
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
This is nice and simple.
ftp://jjlarkin.lmi.net/OpampBoost.JPG
It is also very new and original.
Quote:
The resistor lets the opamp do some of the work at low level,
eliminating the deadband. Sort of. No thermal problems at all.
eliminating the deadband. Sort of. No thermal problems at all.
It won't make much difference if you replace resistor with capacitor. Or
eliminate the resistor at all.
Quote:
We could have a 500+ post thread about which "class" this is.
But why the conservatives didn't kick out Sara Palin? She spoils
everything she touches!
Quote:
I don't understand Ban's circuit.
His circuit is an audiofool way of making emitter follower. The opamp
actually meant to be LM358, as it pulls down.
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
Martin Riddle
Guest
Guest
Sun Aug 29, 2010 3:15 am
"Jim Thompson" <To-Email-Use-The-Envelope-Icon_at_On-My-Web-Site.com> wrote
in message news:vtcj7698r10j7dsu3hcgi56nnhtj1u45ap_at_4ax.com...
Quote:
On Sat, 28 Aug 2010 23:17:43 +0200, "Ban" <bansuri_at_web.de> wrote:
features AB/operation of the output transistors with a bias current of
1.5mA
(set by 15k). The complementary pairs should have a similar beta. To
have a
symmetrical clipping at around +/-11.5V a zener in the positive supply
of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a
whole
magnitude. There is no current limit, so an 100R output resistor
protects
the transistors. Temperature compensation is intrinsic to the circuit,
no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
Ciao
Ban
Apricale, Italy
What a pile of crapola. Did you get that from Larkin ?:-)
...Jim Thompson
--
features AB/operation of the output transistors with a bias current of
1.5mA
(set by 15k). The complementary pairs should have a similar beta. To
have a
symmetrical clipping at around +/-11.5V a zener in the positive supply
of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a
whole
magnitude. There is no current limit, so an 100R output resistor
protects
the transistors. Temperature compensation is intrinsic to the circuit,
no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
Ciao
Ban
Apricale, Italy
What a pile of crapola. Did you get that from Larkin ?:-)
...Jim Thompson
--
But, it has values ;)
Cheers
BobW
Guest
Guest
Sun Aug 29, 2010 4:11 am
"John Larkin" <jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote in message
news:mr9j76d9l19nqmf8bed72e794b04ohbhsv_at_4ax.com...
Quote:
On Sat, 28 Aug 2010 19:02:30 -0500, Vladimir Vassilevsky
nospam_at_nowhere.com> wrote:
Ban wrote:
features AB/operation of the output transistors with a bias current of
1.5mA
(set by 15k). The complementary pairs should have a similar beta. To
have a
symmetrical clipping at around +/-11.5V a zener in the positive supply
of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor
protects
the transistors. Temperature compensation is intrinsic to the circuit,
no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This one is simpler and better in all ways:
http://www.abvolt.com/misc/line_drv.jpg
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
This is nice and simple.
ftp://jjlarkin.lmi.net/OpampBoost.JPG
The resistor lets the opamp do some of the work at low level,
eliminating the deadband. Sort of. No thermal problems at all.
We could have a 500+ post thread about which "class" this is.
I don't understand Ban's circuit.
John
nospam_at_nowhere.com> wrote:
Ban wrote:
features AB/operation of the output transistors with a bias current of
1.5mA
(set by 15k). The complementary pairs should have a similar beta. To
have a
symmetrical clipping at around +/-11.5V a zener in the positive supply
of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor
protects
the transistors. Temperature compensation is intrinsic to the circuit,
no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This one is simpler and better in all ways:
http://www.abvolt.com/misc/line_drv.jpg
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
This is nice and simple.
ftp://jjlarkin.lmi.net/OpampBoost.JPG
The resistor lets the opamp do some of the work at low level,
eliminating the deadband. Sort of. No thermal problems at all.
We could have a 500+ post thread about which "class" this is.
I don't understand Ban's circuit.
John
Neither do I. How do the output devices' bases get their drive?
Bob
--
== All google group posts are automatically deleted due to spam ==
Jim Thompson
Guest
Guest
Sun Aug 29, 2010 4:13 am
On Sat, 28 Aug 2010 20:11:11 -0700, "BobW"
<nimby_GIMME_SPAM__at_roadrunner.com> wrote:
Quote:
"John Larkin" <jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote in message
news:mr9j76d9l19nqmf8bed72e794b04ohbhsv_at_4ax.com...
On Sat, 28 Aug 2010 19:02:30 -0500, Vladimir Vassilevsky
nospam_at_nowhere.com> wrote:
Ban wrote:
features AB/operation of the output transistors with a bias current of
1.5mA
(set by 15k). The complementary pairs should have a similar beta. To
have a
symmetrical clipping at around +/-11.5V a zener in the positive supply
of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor
protects
the transistors. Temperature compensation is intrinsic to the circuit,
no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This one is simpler and better in all ways:
http://www.abvolt.com/misc/line_drv.jpg
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
This is nice and simple.
ftp://jjlarkin.lmi.net/OpampBoost.JPG
The resistor lets the opamp do some of the work at low level,
eliminating the deadband. Sort of. No thermal problems at all.
We could have a 500+ post thread about which "class" this is.
I don't understand Ban's circuit.
John
Neither do I. How do the output devices' bases get their drive?
Bob
It's an old input bias current compensation circuit gone awry by
amateur application
...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Spice is like a sports car...
Performance only as good as the person behind the wheel.
Vladimir Vassilevsky
Guest
Guest
Sun Aug 29, 2010 4:37 am
dagmargoodboat_at_yahoo.com wrote:
Quote:
On Aug 28, 7:02 pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
Ban wrote:
features AB/operation of the output transistors with a bias current of 1.5mA
(set by 15k). The complementary pairs should have a similar beta.
Ban wrote:
features AB/operation of the output transistors with a bias current of 1.5mA
(set by 15k). The complementary pairs should have a similar beta.
[...]
Quote:
Without the diode, the output stage is pulled by resistors only. Diode
helps if there is not enough of current.
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
Guest
Sun Aug 29, 2010 6:24 am
On Aug 28, 7:02 pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
Quote:
Ban wrote:
features AB/operation of the output transistors with a bias current of 1.5mA
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This one is simpler and better in all ways:
http://www.abvolt.com/misc/line_drv.jpg
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultanthttp://www.abvolt.com
features AB/operation of the output transistors with a bias current of 1.5mA
(set by 15k). The complementary pairs should have a similar beta. To have a
symmetrical clipping at around +/-11.5V a zener in the positive supply of
the opamp overcomes the bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a whole
magnitude. There is no current limit, so an 100R output resistor protects
the transistors. Temperature compensation is intrinsic to the circuit, no
thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This one is simpler and better in all ways:
http://www.abvolt.com/misc/line_drv.jpg
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultanthttp://www.abvolt.com
Why the diode?
--
Cheers,
James Arthur
Ban
Guest
Guest
Sun Aug 29, 2010 7:53 am
Vladimir Vassilevsky wrote:
Quote:
Ban wrote:
features AB/operation of the output transistors with a bias current
of 1.5mA (set by 15k). The complementary pairs should have a similar
beta. To have a symmetrical clipping at around +/-11.5V a zener in
the positive supply of the opamp overcomes the bootstrapping action
of the 100u capacitor. Keeping the output transistors conducting reduces
distortion by a
whole magnitude. There is no current limit, so an 100R output
resistor protects the transistors. Temperature compensation is
intrinsic to the circuit, no thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This one is simpler and better in all ways:
http://www.abvolt.com/misc/line_drv.jpg
features AB/operation of the output transistors with a bias current
of 1.5mA (set by 15k). The complementary pairs should have a similar
beta. To have a symmetrical clipping at around +/-11.5V a zener in
the positive supply of the opamp overcomes the bootstrapping action
of the 100u capacitor. Keeping the output transistors conducting reduces
distortion by a
whole magnitude. There is no current limit, so an 100R output
resistor protects the transistors. Temperature compensation is
intrinsic to the circuit, no thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This one is simpler and better in all ways:
http://www.abvolt.com/misc/line_drv.jpg
Sorry, but it has the same number of parts, and try to establish a stable
bias current from -25° to 125°. The variation is less than 5%.
The distortion at 10kHz 20Vpp 100R load is less than 0.025%. With some
4401/4403.
ciao Ban
Ban
Guest
Guest
Sun Aug 29, 2010 8:07 am
John Larkin wrote:
Quote:
Ban wrote:
features AB/operation of the output transistors with a bias current
of 1.5mA (set by 15k). The complementary pairs should have a
similar beta. To have a symmetrical clipping at around +/-11.5V a
zener in the positive supply of the opamp overcomes the
bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a
whole magnitude. There is no current limit, so an 100R output
resistor protects the transistors. Temperature compensation is
intrinsic to the circuit, no thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This is nice and simple.
ftp://jjlarkin.lmi.net/OpampBoost.JPG
The resistor lets the opamp do some of the work at low level,
eliminating the deadband. Sort of. No thermal problems at all.
We could have a 500+ post thread about which "class" this is.
I don't understand Ban's circuit.
features AB/operation of the output transistors with a bias current
of 1.5mA (set by 15k). The complementary pairs should have a
similar beta. To have a symmetrical clipping at around +/-11.5V a
zener in the positive supply of the opamp overcomes the
bootstrapping action of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a
whole magnitude. There is no current limit, so an 100R output
resistor protects the transistors. Temperature compensation is
intrinsic to the circuit, no thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
This is nice and simple.
ftp://jjlarkin.lmi.net/OpampBoost.JPG
The resistor lets the opamp do some of the work at low level,
eliminating the deadband. Sort of. No thermal problems at all.
We could have a 500+ post thread about which "class" this is.
I don't understand Ban's circuit.
The resistor onthe upper left drives 1mA into the emitter of the PNP, from
which most will be taken by the collector, only 1/beta will flow out of the
base into the base of the NPN O/P transistor. This causes the same quiescent
current flowing in the output pair.
Temperature variation is minimal, since we do not have a bias voltage but
current drive, and the first transistor adjusts its base current
accordingly.
ciao Ban
Ban
Guest
Guest
Sun Aug 29, 2010 9:05 am
Jim Thompson wrote:
Quote:
On Sat, 28 Aug 2010 23:17:43 +0200, "Ban" <bansuri_at_web.de> wrote:
features AB/operation of the output transistors with a bias current
of 1.5mA (set by 15k). The complementary pairs should have a similar
beta. To have a symmetrical clipping at around +/-11.5V a zener in
the positive supply of the opamp overcomes the bootstrapping action
of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a
whole magnitude. There is no current limit, so an 100R output
resistor protects the transistors. Temperature compensation is
intrinsic to the circuit, no thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
Ciao
Ban
Apricale, Italy
What a pile of crapola. Did you get that from Larkin ?
features AB/operation of the output transistors with a bias current
of 1.5mA (set by 15k). The complementary pairs should have a similar
beta. To have a symmetrical clipping at around +/-11.5V a zener in
the positive supply of the opamp overcomes the bootstrapping action
of the 100u capacitor.
Keeping the output transistors conducting reduces distortion by a
whole magnitude. There is no current limit, so an 100R output
resistor protects the transistors. Temperature compensation is
intrinsic to the circuit, no thermal runaway should occur.
.--------o------------o--o
| | | +15V
| .-. |
| | | |
| | |15k |
z '-' |
2.7V A | |
| .-----o |
| | \| |/
| --- PNP |--------| NPN
| --- >| |
| |100u | |
___ | | | ___ | ___
o--|___|-o---)--)-----)---|___|----o-|___|-o
in 10k | | | | 10k | out
| | | | |
| | | \| |/
| | | NPN |--------| PNP
| |\| | <| |
'-|-\ | | |
| >-o-----o |
o--------o-|+/ .-. |
GND | |/| OP27 | | |
| | | |15k |
=== | '-' |
GND | | | -15V
'--------o------------o--o
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
Ciao
Ban
Apricale, Italy
What a pile of crapola. Did you get that from Larkin ?
Larkin will like it a lot after he has put it in the simulator and compared
to his circuit, maybe you should do it too?
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