Thor, an all discrete Lateral FET Headphone Amplifier.

[Neutrality]

Thor Supply CapMultiplier board in progress.

Some component values still not decided as well as the transistors in the capmultiplier but I have a few ideas.

The Cap Multiplier part of the supply circuit will be using a star ground to minimize hum.

 

[Avro Arrow]

I might be interested in a pair of Mk2 amps boards depending on final price.

 

[Neutrality]

I might be interested in a pair of Mk2 amps boards depending on final price.

Price would be $25 USD for a pair of MKII boards if I ever decide to get some boards made, not totally decided on that just yet.

 

[Neutrality]

It is not a perfect star but I think it would work quite well anyway.

 

[Avro Arrow]

You should just make a polygon and fill that whole area up.
Thats more like a spider than a star

 

[Avro Arrow]

Here is an example of a dual rail board I did:

DIY Lab Power Supply

 

[Neutrality]

You should just make a polygon and fill that whole area up.
Thats more like a spider than a star

Haha, yea, it looks like a spider.

However, I'm not sure a ground plane is a good idea for a cap multiplier.

What info I could find suggets a star ground layout for cap multipliers or atleast using something star-like.

But then again that was with nothing else than the cap multiplier connected after rectification, with LM317/LM337 as preregulation it might not be needed.

 

[Avro Arrow]

Maybe double the thickness of the center trace and end it at C13.
Polygon around the ground connections.
Try and get the other traces to come into the center trace closer together.

Good job on the project so far!

 

[Neutrality]

Well, think I'm going with a ground plane.

Supply board should be done soon, just have to do a little more simulation and finding the correct transistors and resistor values.

Board should be ordered, mounted and tested some time in the beginning of april if all goes well.

 

[Neutrality]

Transistors will be BC546/556 or BC547/557 preferably in C grade and BD135/136 or equivalent for the main pass transistor.

Gerber.

 

[Avro Arrow]

That power board looks really nice now...well done!

 

[Avro Arrow]

Here is a tip for Eagle...
Those heat sinks with pads have have pins in the schematic.
You can tie the heat sink pad to a net if you wish.

 

[Neutrality]

Here is a tip for Eagle...
Those heat sinks with pads have have pins in the schematic.
You can tie the heat sink pad to a net if you wish.

I know, but I like to keep heatsinks isolated from the circuit, including isolated from ground.

 

[dirkwright]

I know, but I like to keep heatsinks isolated from the circuit, including isolated from ground.

I have heard that this can sometimes lead to problems.

 

[Neutrality]

I have heard that this can sometimes lead to problems.

Out of interest, what problems might that be?

 

[Neutrality]

No-thump boards are on their way, should get them sometime next week, so I hope I have some spare time to get them mounted and tested when I get them.

 

[mnturner]

I've never seen it happen, but I've heard about it causing OscillatIon in power amp output stages

 

[Neutrality]

I've never seen it happen, but I've heard about it causing OscillatIon in power amp output stages

Interesting. That is something to think about then.

 

[Neutrality]

Did some re-thinking and subsequent re-designing of my supply.

Zener voltage reference with pass transistor follow by a cap multiplier using a 4A, 750 Hfe darlington transistor.

Ripple below 1 mV p-p in simulation at full load.

Starground with dual stars.

 

[Neutrality]

Thinking about using the TL431 precision reference as a low-noise voltage reference replacing the 15V Zener.

I'm worried that using a zener will produce too much noise.