Help need protection circuit for this amp

[netiks]

I need short circuit overload protection circuit for this amp
please help

 

[tvrgeek]

Guess you are as out of luck as I. I too was looking for some suggestions on protection circuitry. Zero replies.

When you say short circuit,
You could mean output failure, over-current while operating or output test before power up? Add in thermal sensing and DC sensing and that is about the full gambit. Might start on Elliot Sound Products and look at his board. Jan Diddon has a design that includes a custom made relay. Google a bit. There is a lot out there on add on circuits. Not much on internal circuit protection.

 

[tvrgeek]

I know this is not the question you asked, but is this something you have or are planning on building? This circuit does not take advantage of current best practices.

 

[richie00boy]

There is no short circuit protection that you can add on to an amp, the protection has to be designed with the output devices and voltage rails in mind and shut down part of the amp circuit, you can't do this with a separate board.

Rod Elliott has a protection board that will proptect the speaker, but for an amp the size of that in the first post the relay is likely to fail.

 

[Pingrs]

Bonsai posted a thread featuring Michael Kiwanuka's design procedure for VI limiting.
Read that.

 

[tvrgeek]

http://www.diyaudio.com/forums/solid-state/235841-michael-kiwanukas-soa-paper.html

Super. Much thanks.

 

[east electronics]

First you need to have a protection circuit that will protect the ""megatech amplifier"" from his self
then you need to design or apply other forms of protections such is VI limiting , for the outputs , overload protection . Input overdrive protection, thermal protection and so on

 

[netiks]

re

Is it possible to implement short circuit protection directly on PSU overcurent?
where can I find circuit and pcb for overcurent protected psu Is that going to protect amplifier output transistors or no?
thanks

 

[netiks]

I found circuit of protection with clip sig pro temp led indicators and fan control
If I could just add some protection for short circuit on Power Supply or to put some sensing circuit on output transistors but I dont like idea of having 2 separate protection circuits each heaving relay or maybe it want work with two separate protection circuits
Thats why I was thinking to make short protected PSU but I dont know will that protect output transistors?

 

[netiks]

Here is the circuit and pcb it uses uPC1237 and protect amplifier from overcurrent and low impedance on output short circuit protects speakers from dc and thurn on delay
but if I put this protection circuit with relay how to connect another protection circuit for over temperature DC clip sig pro power indicator with fan controll which has another relay

uPC1237 Amplifier/Speaker Protection Module | DIY AUDIO BLOG, AUDIO WORKSHOP

 

[netiks]

There are automatic fuses (circuit braker) they are much faster than standard fuses they are rated in amps like regular fuses and will instanly protect amplifier from over current
But I dont like idea of putting those auto fuses on chasis of amplifier it will look ugly
Or maybe to install them on the amplifier back?

automatic reset mini breaker fuse, View automatic reset mini breaker, FAIZCO Product Details from Yueqing Kangling Electric Appliance Factory on Alibaba.com

ABB ABB Circuit breaker K 32 A from Conrad Electronic UK

Crabtree 61/B32 32 amp 32A MCB Starbreaker 32AMP B Fuse Board Circuit Breaker | eBay

 

[east electronics]

Is it possible to implement short circuit protection directly on PSU overcurent?
where can I find circuit and pcb for overcurent protected psu Is that going to protect amplifier output transistors or no?
thanks

Your approach is wrong any circuit that works on the power supply will sense audio signals and dynamic peaks as overcurrent ...In real life this is what you actually expect from an amplifier power supply : to be able to ""behave"" when the amplifier need juice plenty and quickly ...

Let me tell you a few other things that you may don't understand or willing to listen ...

The circuit of your amplifier is very generic ..that is a very good think when it comes to sound since overcomplicated circuits tend to sound worst Though at this rail voltage the amplifier will demand current and this will easily will come out of control and the transistor that will have to handle this current will fail .

Miller compensation on your amp is roughly calculated to an also generic value input filtering at 1nf looks pretty weird ( unless the original circuit was intended for a sub woofer amplifier )

Obviously a circuit like that will require a perfectly made pcb and at rail
of 60-90 volts you need to ensure that both rails and outputs may provide enough rail and output to each and every transistor and equally if possible .

There is more but these are the basics

In a few words if this amplifier is made for average domestic use it will work but if its made to pro work it will fail pretty quickly.

Kind regards
Sakis

 

[east electronics]

if made for pro use a VI limiter is in order and the type of one that senses from each and every transistor separately. That of course will increase the load on VAs and then may be more calculations may be also needed ....

This is the forms of "protection " i am talking about and expect the rest such DC , thermal , overload and over current and probably input limiting as the next step to complete the project

Kind regards
Sakis

 

[netiks]

if made for pro use a VI limiter is in order and the type of one that senses from each and every transistor separately. That of course will increase the load on VAs and then may be more calculations may be also needed ....

This is the forms of "protection " i am talking about and expect the rest such DC , thermal , overload and over current and probably input limiting as the next step to complete the project

Kind regards
Sakis

Thank You my friend for good explanation can You tell me please how can I connect VI limiter circuit on this amplifier?
Regards

 

[east electronics]

Actually No ... that will require plenty of calculations and actual real life tests on a given pcb
..as usual practice many so called "designers" present circuits like that and many better and expect other people to debug them or advance them from a simple schematic to a completely working and even idiot proof product ..

So i am sorry it will be a NO

Kind regards
Sakis

 

[netiks]

Actually No ... that will require plenty of calculations and actual real life tests on a given pcb
..as usual practice many so called "designers" present circuits like that and many better and expect other people to debug them or advance them from a simple schematic to a completely working and even idiot proof product ..

So i am sorry it will be a NO

Kind regards
Sakis

I didnt design that circuit I just found it on the net I just wanted to learn how to implement VI limiter on amplifier circuit but never mind

 

[netiks]

I saw a lot of amplifier designs without VI limiters and working fine protection cricuit from short can work on shunt resistor and can protect amplifier from short

 

[Vostro]

Look for Apex AX11 psu with dc protect and short circuit protection.
This should be sufficient protection for home use.

But for home use scale amp to 100W to 150W.
If you want to use for pro use. Then you'll need better protection
Regards

 

[netiks]

Look for Apex AX11 psu with dc protect and short circuit protection.
This should be sufficient protection for home use.

But for home use scale amp to 100W to 150W.
If you want to use for pro use. Then you'll need better protection
Regards

Thanks Vostro
I need amplifier protection for 1000w rms 8ohm amplifier AB class
short circuit protection on output of the amplifier its not for home use
Best Regards

 

[andrewlebon]

OMNI PROTECTOR by dr BORA