Crowbar can't function with low voltage power supply.
Crowbar can't act as delay circuit.
Crowbar contact is a catastrophic failure.
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Crowbar working from 8 V DC and 100% safe to protect your Speaker and, parts cost 2 USD
Delay circuit ist very simple, also about 3 USD parts count if amplifier is not well designed to avoid turn on off thumps, have seen last 20 years a lot of rubbish schematics from Hi-Fi designer
an failed amp is catasttophic failure and need reliable DC
Protect
please update Hi-Fi skills and learn from other
risk for amplifier short Output to Ground same crowbar does with full Output power?
,...come on LOL,
Then its rubbish not well designed amplifier !!!
Throw it away or use as doorstep.
Designer need to learn from other to add protection and not copy and paste schematics without understand basics.
I can short amplifier everytime and anytime with full load output power same crowbar does and all is fine.
after remove short, the amplifier play again music and hundreds of people can dance
Project 120
'' Needless to say, using the circuit with supply voltages less than around 40V is not recommended, as you will have a false sense of security. ''
'' Needless to say, using the circuit with supply voltages less than around 40V is not recommended, as you will have a false sense of security. ''
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LKA was good enough to publish his working design and yet people get on this thread every so often to criticize and boast that their design is better.
Talk is cheap and as I said previously, show us your design or start your own thread.
Better still, ask your self why you are posting????
If your comments are NOT constructive, you have a problem with your character, that you need to correct!
Talk is cheap and as I said previously, show us your design or start your own thread.
Better still, ask your self why you are posting????
If your comments are NOT constructive, you have a problem with your character, that you need to correct!
I haven't really considered the crowbar approach as there has been some, possibly unwarranted, criticism of its shortfalls. It would take time that i don't have, to understand those comments so I have stuck with "if it ain't broke, don't fix it" approach.
So I have used the conventional spkr protect topology developed by Silicon Chip, and others on this forum and even some "esteemed"
amplifier book authors, for well over 18 years. The approach is very simple and many have used the same configuration of trannies but with different caps and resistor values to achieve the same thing. I have played with some of the values but many of the changes have made no difference. The main components to "play" with are those setting the start-up time.
I also have the mainly "diode-based" version but haven't focussed on it since I have plenty of signal transistors and what I have has worked Ok.
I took out the mechanical relay a while back and replaced it with the Si8752 and MOSFETS, using information and recommendations from Rod Elliot's articles, another thread here, and the application notes, and have been running it for a decent period of time with no issues. The amplifiers it is used with, use MOSFETS as outputs and are 50 - 100W rated output but I never crank them up as my old speakers have 93db sensitivity so they generate a lot of sound.
The circuit is, as i said, conventional and the mechanical relay is replaced by the 680R resistor and Si8752s and MOSFETS. It will run on amplifier supplies from 40 - 60V comfortably as the circuit has its own ~30V operating voltage via the linear regulator (MJE3055 + zener). The MJE3055 can be heatsinked if necessary. The board size is 68 x 85mm for a stereo setup and I have played around with different layouts to try to better match the amplifiers geometries and associated other components. When i get back to a PC on my network, i will try to find the board drawings.
View attachment SpkrprotectwMOSFETs.pdf
So I have used the conventional spkr protect topology developed by Silicon Chip, and others on this forum and even some "esteemed"
amplifier book authors, for well over 18 years. The approach is very simple and many have used the same configuration of trannies but with different caps and resistor values to achieve the same thing. I have played with some of the values but many of the changes have made no difference. The main components to "play" with are those setting the start-up time.I also have the mainly "diode-based" version but haven't focussed on it since I have plenty of signal transistors and what I have has worked Ok.
I took out the mechanical relay a while back and replaced it with the Si8752 and MOSFETS, using information and recommendations from Rod Elliot's articles, another thread here, and the application notes, and have been running it for a decent period of time with no issues. The amplifiers it is used with, use MOSFETS as outputs and are 50 - 100W rated output but I never crank them up as my old speakers have 93db sensitivity so they generate a lot of sound.
The circuit is, as i said, conventional and the mechanical relay is replaced by the 680R resistor and Si8752s and MOSFETS. It will run on amplifier supplies from 40 - 60V comfortably as the circuit has its own ~30V operating voltage via the linear regulator (MJE3055 + zener). The MJE3055 can be heatsinked if necessary. The board size is 68 x 85mm for a stereo setup and I have played around with different layouts to try to better match the amplifiers geometries and associated other components. When i get back to a PC on my network, i will try to find the board drawings.
View attachment SpkrprotectwMOSFETs.pdf
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a well designd Amplifier no need additional speaker protection
BOM is very high for this circuit, to protect toys 50 to 100 W for living room,
you can handle 2500 W RMS with a simple crowbar to save speaker
If you have experience to design and service amplifier in KW Range Rails +/- 180 V DC
you wlll agree
BOM is very high for this circuit, to protect toys 50 to 100 W for living room,
you can handle 2500 W RMS with a simple crowbar to save speaker
If you have experience to design and service amplifier in KW Range Rails +/- 180 V DC
you wlll agree