Servo & speaker protection combo

Wavebourn · 9th August 2009, 02:40 AM

Here is what I am going to use as a servo and speaker protection.

Speaker protection is triggered by clipping of servo, i.e. when there is some voltage greater than 0.3V on it's inverting input. Opamps are TL061

Any comments/suggestions?

AndrewT · 9th August 2009, 02:57 PM

is it really a clipping detector?
or,
is it a window comparator between signal ground and the signal input to the servo opamp?

Why do the two diode cause triggering @ ~300mV?

sivan_and · 9th August 2009, 04:16 PM

...an LED in series with the relay ?...IC 555 will drive the relay directly ..the circuit around the trigger...

need lots of modifications to work properly...
"AndrewT " do the two diode cause triggering @ ~300mV?"
suppose he used low drop schotky diodes..

Wavebourn · 9th August 2009, 04:58 PM

Thank you both. I am going to make a PCB, if no suggestions.

Bob Cordell · 9th August 2009, 05:02 PM

Hi Wavebourn,

Great minds think alike. I have used the output of the servo as a trigger for speaker protection for several years. I put a window detector on the output of the integrator and use it to open the speaker relay if the magnitude of attempted correction by the servo is greater than about half the available correction voltage.

Cheers,
Bob

Wavebourn · 9th August 2009, 05:21 PM

Quote:

Originally posted by Bob Cordell
Hi Wavebourn,

Great minds think alike. I have used the output of the servo as a trigger for speaker protection for several years. I put a window detector on the output of the integrator and use it to open the speaker relay if the magnitude of attempted correction by the servo is greater than about half the available correction voltage.

Thank you Bob;
I used similar approach before, but now decided to allow servo to try all it's best and to trigger protection as soon as servo can't keep up anymore, and voltage on it's inverting input abruptly changes.
I will probably need 2 more diodes, to protect inputs of opamps from an overvoltage.

AndrewT · 9th August 2009, 05:23 PM

Quote:

Originally posted by sivan_and
...IC 555 will drive the relay directly ..

24volt relay.
7555 powered from 12V.
How?

sivan_and · 10th August 2009, 01:20 AM

Quote:

Originally posted by AndrewT

24volt relay.
7555 powered from 12V.
How?

use 12 volt relay

(& reduce 24 to 12 relay driving volts)

Wavebourn · 10th August 2009, 03:09 AM

Quote:

Originally posted by sivan_and

use 12 volt relay (& reduce 24 to 12 relay driving volts)

Unfortunately I have no 15A relays with 12V coil that can be driven by less than 100 mA current; all 15A relays I have need 24V 20 mA.
Couple of advantages are: I can use LED in series with the relay, and I can keep 12V rail, that is used for a servo as well, clean. However, there is one more advantage: industrial control transformers with 18V secondaries I have will fit well in this particular application.

sivan_and · 10th August 2009, 06:33 AM

am afraid your design is for your personal use, and unsuitable for universal use..

9th August 2009, 02:40 AM	#1
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	Servo & speaker protection combo Here is what I am going to use as a servo and speaker protection. Speaker protection is triggered by clipping of servo, i.e. when there is some voltage greater than 0.3V on it's inverting input. Opamps are TL061 Any comments/suggestions? __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

9th August 2009, 04:16 PM	#3
sivan_and diyAudio Member Join Date: Dec 2004 Location: Dxb / India	...an LED in series with the relay ?...IC 555 will drive the relay directly ..the circuit around the trigger... need lots of modifications to work properly... "AndrewT " do the two diode cause triggering @ ~300mV?" suppose he used low drop schotky diodes.. __________________ SivanandBalan

9th August 2009, 04:58 PM	#4
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	Thank you both. I am going to make a PCB, if no suggestions. __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

10th August 2009, 06:33 AM	#10
sivan_and diyAudio Member Join Date: Dec 2004 Location: Dxb / India	am afraid your design is for your personal use, and unsuitable for universal use.. __________________ SivanandBalan

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9th August 2009, 02:57 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	is it really a clipping detector? or, is it a window comparator between signal ground and the signal input to the servo opamp? Why do the two diode cause triggering @ ~300mV?

9th August 2009, 05:02 PM	#5
Bob Cordell diyAudio Member Join Date: Sep 2006	Hi Wavebourn, Great minds think alike. I have used the output of the servo as a trigger for speaker protection for several years. I put a window detector on the output of the integrator and use it to open the speaker relay if the magnitude of attempted correction by the servo is greater than about half the available correction voltage. Cheers, Bob

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