diyAB Amp The "Honey Badger" build thread

Current limiter for HB may look like the one in the attachment
That looks like a variant of the output current limiter I posted. Something like this is used on some "Leach type" symmetrical designs for the VAS , as well. (NO ,Kay) On the Badger , altering VAS impedance is the concern. The TMC would be affected. A EF2 or EF3 output stage will not load the VAS dangerously. With the Badger, it is the beta enhanced follower that has internal saturation , not a external overload. The diode or (not clipping) takes care of that. Using this diode (vas) limiter and 3rd party DC/current protection is the usual "audiophile way". :D My H/K integrated amp uses the badger topology in this way - plus a upc1237 protection IC. Watch out , most Ebay/Chinese upc1237 solutions DO NOT include the overcurrent function ... (only delay + DC). Only a few add the extra couple transistors/diodes to pin 1 of the 1237. There will be an extra connector with pnp or npn designations (like below "A") - cheap !! 5-10 usd . RESEARCH the purchase.

OS
 

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  • overcurrent.png
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So it was your design. I copied it from one of the HB threads but do not remember which one. I gave it as an example. One can easily recalculate resistor values to suit ones needs. I did my calcs for SS9014/15 transistors and 12A and 15A load.

Ostripper,

What is J1 in your circuit?

cheers,
 
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The relay coil. See the back EMF diode in parallel with it. As far as the in circuit current clamp protection. Back EMF of a big woofer can affect it , it might ?? add a few PPM to the mix. On my Slewmaster , Re's have euro connects to be monitored by external protection circuits. Low Rdson MOSFET's then disconnect the short. Edit - same as a output fuse . Not audiophile , "wire with gain" has no fuse. It seems the current clamp is a cheap warranty "reducer" reserved for lower end consumer products.

OS
 
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prevent oscillation

My point exactly , why not just disconnect the speaker ?

Outputs are cheap , speakers are not.

Adding a positive feedback loop to the output stage is so "20'th century". PS - with older (slower) 90's output devices , clamps were "behaved" .With 21'st century 60mhz devices ,different story.

I am actually designing a class G OP stage with positive feedback now. Actually using a simulation probe to push the class G feedback above the Ft of the core AB stage.

Do as you want ..... :rolleyes:
OS
 
I do not like the idea of adding a relay betwen amplifier and speaker .... I try to reduce resistance as much as possible ..
MOSFET = super low Rdson ,less than some wire. https://www.onsemi.com/pub/Collateral/NDPL180N10B-D.PDF

Two of them form a solid state relay that can disconnect a speaker at the speed of the protection circuitry. http://hifisonix.com/wordpress/wp-content/uploads/2012/08/Speaker-Relay-V1.03.pdf

A mechanical relay is also "20'th century".;)

OS
 
Do not forget tu use a pair of capacitors to prevent oscillation.
They should be betwen base of protection transistor ( T1 & T2 ) and V out

Yes, of course. In old times I used a circuit like the one in Cordel's book.

ostripper,

So J1 is 24V relay's coil and S1 is the relay switch - am I right?
thank you,

cheers,
 

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  • Simple current limiter circuit Cordel 1.jpg
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Hi All.

Just been doing a bit more back to basics to help me better understand some of the building blocks of the HB and had the following Question in relation to the input network.
I am assuming that R1,2,3 combined with C1,2 form some form of low pass / high pass filter?
I assume that the coupling capacitor C1 blocks any DC that might be present from the source.
I assume that R3 provides a return path for the input bias current of the amplifier’s input stage. This also keeps the non inverting input node of the amplifier near 0 V.

I assume that the capacitance of C1 against R3 forms a high-pass filter.
I assume that the resistor R2 and capacitor C2 form a first-order input low-pass filter.
I assume that the resistor R1 keeps the input terminal from floating at DC.

If so can someone please provide some more information if this is correct and tell me why active filters are not used?
 
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Hi everyone.
I apologize for the English but I'm using a translator.
I bought these boards v 2.4, mounted the whole thing but when I turn on R53 R54 jump, I tried and the LEDs light up properly only remove driver Q15, without this the tensions seem correct.
What can I check?
Is there a short circuit somewhere?

Thank you in advance.