The Mini-A

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#243
Coulomb said:
jleaman said:



Yup,! Pretty expencive hobby, however im going to be building some audio stuff this winter, 😛

Jase

I see you put down a tarp so when you crash you can roll all the parts and take it home. 🙂
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HAH! I wish, no when i crash i crash good 😛 the tarp is for trimming the servos adn doing hand's off, and stuff 😛
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#244
preamp for mini A

Ok , once again I build a mini as graduation gift great way to share. This time I will build integrated amp, looking for compact preamp design. Since it will probably be fed from a Ipod single ended would be ok, but balanced out would be a bonus. Any Ideas ?

Bill
 
#245
Re: preamp for mini A

wirewiggler said:
Ok , once again I build a mini as graduation gift great way to share. This time I will build integrated amp, looking for compact preamp design. Since it will probably be fed from a Ipod single ended would be ok, but balanced out would be a bonus. Any Ideas ?

Bill
Click to expand...


Balanced out from a ipod as a source, YUK! just use the analogue, and run a pot for a passive volume control.
 
#247
Hi guys,

I got my mini-A boards from BrianGT and ordered all resistors with .125w rating other than the 3w source resistors. I found the .125w fits better on this small boards.
Are .125w ok for this application?

Albert

BTW I ordered some more at the same time for F4 & F5 too. Or I've to re-order them otherwise.
 
#248
albertli said:
Hi guys,

I got my mini-A boards from BrianGT and ordered all resistors with .125w rating other than the 3w source resistors. I found the .125w fits better on this small boards.
Are .125w ok for this application?

Albert

BTW I ordered some more at the same time for F4 & F5 too. Or I've to re-order them otherwise.
Click to expand...


You can stand them up like how i did, or use the smaller ones, the only resistors that matter for power/current are the main 3watt ones. Other than that you'll be ok.
 
#251
Power Supply PCB

Hi,

just curious if anyone used resistors on the brian gt power supply pcb for the mini-a. There are footprints for up to 5 resistors per rail.

how do these .47 ohms in parallel help to reduce noise?
I see a similiar circuit on the F4/F5 power supply using 4 resistors per rail.

thx.
 
#252
Re: Power Supply PCB

Bengali said:
Hi,

just curious if anyone used resistors on the brian gt power supply pcb for the mini-a. There are footprints for up to 5 resistors per rail.

how do these .47 ohms in parallel help to reduce noise?
I see a similiar circuit on the F4/F5 power supply using 4 resistors per rail.

thx.
Click to expand...


I used 4 large resistors in parallel on my Brian GT PSU boards to drop a couple of volts in a CRC arrangement.

-David
 
#254
You might want to play with PSU Designer 2 from Duncan Amp
Tools. When I pluged in a power supply using a 20v transformer
with 1 ohm source resistance ,25A bridge rectifier then a CRC
using 20,000 uf .1ohm 20,000uf and 20,000uf loaded at 1.5A the ripple was about 6db less than using just 2 20,000uf caps in parallel without the .1ohm resistor.
 
#256
It sings!!

My Mini-A is finally done and has been singing for 3 days.
It wasn't as smooth sailing as I would hope, but each time it didn't work, I reread the
previous posts, looked at the schematic, took measurements, and tried whatever fixes that I thought would be the cause. I really learned a lot through out this kind of exercise. Casualties weren't that bad - 2 x ZTX450, 1 x IFP9610, and 2 fuses, plus a few drops of my precious blood ....

It is time to say thank you and a big cyber hug to Papa and Grey to share such fantastic design.

Here are a few photos of the naked and buttoned up Mini-A.

http://s257.photobucket.com/albums/hh207/fredvu/Mini-A/?action=view&current=mini-a-1.jpg
http://s257.photobucket.com/albums/hh207/fredvu/Mini-A/?action=view&current=mini-a-1.jpg
http://s257.photobucket.com/albums/hh207/fredvu/Mini-A/?action=view&current=mini-a-1.jpg

Thanks again!!
 
#258
Re: It sings!!

pchw said:
My Mini-A is finally done and has been singing for 3 days.
It wasn't as smooth sailing as I would hope, but each time it didn't work, I reread the
previous posts, looked at the schematic, took measurements, and tried whatever fixes that I thought would be the cause. I really learned a lot through out this kind of exercise. Casualties weren't that bad - 2 x ZTX450, 1 x IFP9610, and 2 fuses, plus a few drops of my precious blood ....

It is time to say thank you and a big cyber hug to Papa and Grey to share such fantastic design.

Here are a few photos of the naked and buttoned up Mini-A.

http://s257.photobucket.com/albums/hh207/fredvu/Mini-A/?action=view&current=mini-a-1.jpg
http://s257.photobucket.com/albums/hh207/fredvu/Mini-A/?action=view&current=mini-a-1.jpg
http://s257.photobucket.com/albums/hh207/fredvu/Mini-A/?action=view&current=mini-a-1.jpg

Thanks again!!
Click to expand...


Heat sinks aren't needed for the 3 fets that are on the amplifier board, they don't get that warm. Also make sure they are not touching if you keep them.



J'
 
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