[oohms]

Silicon chip headphone amp (SCHA) in a 3.5" external hard drive enclosure
 
Minimal mods, gain to 4.7, larger low ESR caps, changed values on HF filtering caps
The black box attached to the PCB is a switchmode PSU, 12 to +/-15v - makes less audible noise than any linear PSU i have had
 

 

 

[Avro_Arrow]

Here is a little something I put together to practice my circuit
board making skills. 3 Channel design, gain of 2. Sounds good too!
 

 

 

[ujamerstand]

Cool, which technique did you use to etch your boards? Also, any cheap local supply store I should be aware of?

 

[Avro_Arrow]

I'm using the photo method.
Drawn up in Eagle, laser printed on transparency.
I built my own exposure light.
Chemicals and board are from Sayal.
Sometimes you can find better priced at Active so it
pays to check both places.
Pretty standard stuff, really.

 

[Pageygeeza]

Quote:

 
Pretty standard stuff, really.

Lol, yer kidding?
 
It sure doesn't look standard to me!  It looks flawless!

 

[sandbasser]

Quote:

Here is a little something I put together to practice my circuit
board making skills. 3 Channel design, gain of 2. Sounds good too!
 

 

I'm curious about your batteries...care to share what they are???
 

 

[Avro_Arrow]

They're Lithium Ion salvaged from a laptop battery pack.
I used to work in Laptop repair and I have bags full of them. 

 
Quote:

I'm curious about your batteries...care to share what they are???
 

 

[Avro_Arrow]

Thanks, I guess you didn't see the first couple...
 
 
Quote:

Lol, yer kidding?
 
It sure doesn't look standard to me!  It looks flawless!

 

[Spacehead]

I don't think my protoboard works lose much to those, what you think? Nice work though Avro_Arrow!

 

[Fred_fred2004]

Avro_Arrow
 
Brilliant work, I think the DIY bar just raised another couple of notches
 
congratulations
 
cheers
FRED

 

[Avro_Arrow]

Thanks Fred, I was just trying to keep up with you...
 
Quote:

Avro_Arrow
 
Brilliant work, I think the DIY bar just raised another couple of notches
 
congratulations
 
cheers
FRED

 

[Avro_Arrow]

Here is the amp I did this morning.
It has a split power battery supply.
AD8620 is the op amp. Gain is 2.
 
A word of warning...some op amps will tolerate
mis-matched rail voltages and some will put out
a nasty DC offset. Try this design at your own risk.
 

 

 

[ujamerstand]

I guess its called the hornet for a good reason.

 

[Avro_Arrow]

Exactly.
 
Quote:

I guess its called the hornet for a good reason.

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[jdkJake]

Wow, beautiful etching work avro_arrow!

Really, really nice work.