[mb3k]

I have a feeling the gain of 4 is not high enough for the AD8397 to be stable enough. Tangent, I've tried running off of a single 9V, and the draw is 60mA, but the op-amps still get burning hot.
I'll try swapping R3 & R4 for a gain of 6 and see what I get.

 

[[AK]Zip]

Quote:

Originally Posted by mb3k I have a feeling the gain of 4 is not high enough for the AD8397 to be stable enough. Tangent, I've tried running off of a single 9V, and the draw is 60mA, but the op-amps still get burning hot. I'll try swapping R3 & R4 for a gain of 6 and see what I get.

I am running a gain of 4 with 1 9v and I am having no problems...

-Alex-

 

[sheya]

Perhaps this question will label me as too much of a neophyte to have attempted to build a PINT, but here goes.

I have a minified PINT built, but I haven' t hooked up the power supply yet. I don't know which pad goes to which wire. Where do W-, B-, M+, M-, W+, B+ hookup? I intend to use 2x9volt batteries, so I have two +, two - for the batteries, and one + and one - for the charger. Which pad is for which? I tried figuring it out based on the schematic, but I found it confusing and am not sure.

Any help would be appreciated, I'd like to hook up the power supply correctly so I don't fry the amp in learning how to hook it up.

Thanks-
Aaron.

 

[MisterX]

W+ = External DC input Positive
W- = External DC input negative


For two batteries wired in series:
M+ = Battery 1 Positive
B- = Battery 1 Negative
M- = Battery 2 Negative
B+ = Battery 2 Positive

For a single battery:
B+ = Battery Positive
B- = Battery Negative

Clear enough?

 

[cire]

Quote:

Originally Posted by sheya Where do W-, B-, M+, M-, W+, B+ hookup?

wow, uhm...yeah... here we go: the markings are fairly self explainatory. W- and W+ are the pads for the wallwart, B+ and B- are the pads for the battery and M+ and M- are shorted together and are for if you intend on using two batteries in series.

damn, beaten by the X

 

[mb3k]

Quote:

Originally Posted by sheya Perhaps this question will label me as too much of a neophyte to have attempted to build a PINT, but here goes. I have a minified PINT built, but I haven' t hooked up the power supply yet. I don't know which pad goes to which wire. Where do W-, B-, M+, M-, W+, B+ hookup? I intend to use 2x9volt batteries, so I have two +, two - for the batteries, and one + and one - for the charger. Which pad is for which? I tried figuring it out based on the schematic, but I found it confusing and am not sure. Any help would be appreciated, I'd like to hook up the power supply correctly so I don't fry the amp in learning how to hook it up. Thanks- Aaron.

W+/- is for the wall
B+/- is for the batteries
M+/- are pads that are common points connected together to make it easier/cleaner to connect two batteries.

EDIT: Dang, beaten by both of you. That was really fast.

 

[sheya]

Thanks for your responses, I appreciate your help.

-Aaron.

 

[sheya]

I'm listening to my minified PINT right now with my Etymotic ER4P w/S adaptor. All seems to be well, I'm using the minified version. I have less than 10ma of offset, and the chips are reasonably cool. Now I just have to case it up, making sure to isolate all the jacks from the case.

I obviously haven't been able to do any critical listening or comparison, but at first listen, it sounds very good, using an audioquest ministereo plug to RCA cable, playing CD's through my Parasound CDP1000.

This was my first surface mount project, and it really wasn't difficult at all. The hardest part was seeing which way the diodes are supposed to go, even with a magnifying glass and a bright light it was hard to see the line.

I understand the discontinuation of the project, because of problems that people have had with building the amp, but from my experience of building one PINT (I have two more to build), it isn't difficult or troublesome. Granted, I minified it right away because I didn't order the correct part for the output capacitors, and I had the resistors and other parts to make the minified version on hand.

Thanks to all who have posted in this thread and others about the PINT, reading them helped me a lot in building the amp. And thanks to Tangent for making such a great product that can be built for such an affordable price.

-Aaron.

 

[Heady]

Didn't tangent said he may change his mind and still sell the PINT pcb for at least another lot of pcbs? Maybe tangent will change his mind if enough people ask him nicely?

 

[Heady]

Ok, sorry for re-surrecting this thread even though PINT is no longer available from Tangent.

I asked for help before with my PINT builts. To be fair to Tangent, the second built was fine. It just doesn't want to run at 4.5V which is what I used to power it. When I switched to a 9V battery, the PINT ran fine.

I notice once the 9V battery approaches 6V, I get the strange whistles etc indicating that oscillations are probably present. At 9V, the current draw is about 55mA.

So there, see, Tangent. It wasn't your fault.

 

[splaz]

Okay. Still have not got round to starting one as I'm getting some parts.

Question about the ferrites. Are the DC resistance and current specs important ?

The difference is 0.1 as compared to 0.01 dcr and 500mA compared to 6000mA.

 

[amb]

Quote:

Originally Posted by splaz Question about the ferrites. Are the DC resistance and current specs important ? The difference is 0.1 as compared to 0.01 dcr and 500mA compared to 6000mA.

DC resistance should ideally be low so that it doesn't waste power and negate the low output impedance of the AD8397. The current rating should be high enough to handle the highest output current the amp might deliver without magnetic saturation (which causes distortion). Between your two choices, the "smaller" ferrite with 0.1Ω DCR is more than low enough and 500mA is also more than the opamp's output rating. The "bigger" ferrite would be overkill in this application. Would it even fit the space on the board?

 

[splaz]

Both are 1206. Different manufacturers.

Better spec one is Maruta, 33 ohm @ 100MHz, it's in tangent's part list, from Mouser.

The lower spec is Fair-rite 30 ohm @100MHz, from RS Components.

Closest value I can get relatively easily. Good to hear the specifications are fine though.

 

[splaz]

Okay. Every single part except this one I have sorted.

C6. I've read through the parts selection guide. Tangent says that it is not needed, sort of a 'just in case' part. I'd rather have it in. Problem is I can't seem to easily find a 4.7 microfarad in 35V in the right package size. I can however fairly easily get a 2.2 microfarad in 35V rating.

Thing is, does 2.2 still fulfil the purpose of the part ?

Tangent stated that it provides additional bypassing in the frequency between C4 and C5. I'm assuming the value is important to that function.

 

[quicksilver96]

On Tangent's parts list, he has "4.7+ µF/25 V tantalum caps, 3528-21 size" listed. I used Digikey P/N 399-3368-1-ND, 6.8 µF/25 V tantalum caps in the above size. They are $1.35/ea, I have a few extra PM if you want a couple.