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Loudspeaker protection

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mhtplsh

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loudspeaker protection

Here is a circuit suggested by my friend. But it is very old & for small tweeter. I want to use it for 40~60W compression driver(Tweeter). So it need to be more reliable & modified .
Waiting for suggestion & modifications required.
 

loudspeaker protection diode

i think that circuit would be just fine because it switches off the connection based on input power.... maybe you can change the bias conditions and the transistor for faster switching....

what more upgrades do you expect in this circuit....
 

loudspeaker protection relay

I want to use 12V relay, so accordingly i will change the bias resistor of T2. Also changing zener diode to nearabout 9V.
Waiting 4 comments.
 

circuit loudspeaker protection

in that circuit if you replace the diode by a 9V zener then the current drive of the zener->current source->LED would get reduced since the voltage across the 100Ω is reduced and this would reduce the current drive of the transistor T2 and hence the switching of the circuit would be slow.....

there is no difference in the relays.... a relay switches when current flows through it... a 12V relay means its coil can tolerate 12V across it but the switching of relay is going to be the same.....
 

kit loudspeaker protection

First of all, I am very suspicious about circuits that use capacitors connected in parallel with RLY coil to stop chattering ..
Also, keep in mind that some amplifiers "don't like" working without load(s) ..

Here:
**broken link removed**
is a loudspeaker protection unit which rather than disconnecting load inserts a resistor in series with loudspeaker ..
And, the sensitivity is adjustable (potentiometer) - not set by a zener diode ..

Regards,
IanP
 

bf245a as current source

A.Anand Srinivasan:
if you replace the diode by a 9V zener then the current drive of the zener->current source->LED would get reduced since the voltage across the 100Ω is reduced and this would reduce the current drive of the transistor T2 and hence the switching of the circuit would be slow
Click to expand...

The circuit is for very small tweeter hence low voltage. My input voltage will be almost 2~3 times higher hence thinking of changing zener value.

IanP

There is no component value. So difficult to try the circuit. It it would hv been in my country i would hv purchased the kit 4 DIY.

Can we replace the relay with power Mosfet as switch. Then driver it in such a way that it will control the signal. More the input voltage more the attenuation through Mosfet.
 

loudspeaker protection circuits

i think using MOSFET is a better idea because you dont have to worry about the problem of inductive kickback.....
 

diy loudspeaker protection

A.Anand Srinivasan:
think using MOSFET is a better idea because you dont have to worry about the problem of inductive kickback
Click to expand...

Can u suggest some mosfet with min 15A~25A max current capacity & circuit modifications reqd.
 

that amount of current is too high for any MOSFET, i have seen power MOSFETs of current rating of 5A only..... maybe you can use 2 or more MOSFETs in parallel.... MOSFETs dont suffer that much problem when used in parallel unlike BJT......
 

for using mosfet instead of relay, i will hv to isolate it with opto coupler to drive it. Further the signal is AC.
Which will be more faster transistor in place of BD 139?
or should i use TIP122 darlington to drive relay?
 

using darlington pairs are generally slow since it involves the turning on of two transistors.... try searching for high speed transistors or use a schottkey transistor..,,,,,
 

    M

    mhtplsh

    Points: 2
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for the current source BF245A fet is used. Can i replace it with some BJT?
 

that particular circuit is a current diode configuration.... since a FET is being used the current source is stable to variation in temperature(due to surrounding as well as heating).... if BJT current source is used then you have to worry about biasing it as well as thermal runoff....
 

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