[Nospam]

I just learned that, apparently, it's not a good idea to wire NiMH batteries in parallel... I had planned to do just that with my next MINT, since I'll be using the AD Op-Amps which don't need much voltage. Besides, I really didn't notice any sound quality differences when testing my first MINT (9.6V vs 19.2V)

So, if I use the Altoids tins, is it still worth it to wire the batteries in series?

If I decide to just use a single battery, what could I do with the extra space?

A few things that have occurred to me are (using Altoids tin and single 9V):
Put in a recharging circuit.
Add a power jack for non-portable applications.
Get rid of the power switch and see if the switching Pot can fit.

I could also go with a different, more durable case and a single 9V (to minimize the size).

Any other ideas?

Once I move into my new apartment, I should have enough room (and hopefully free time) to start playing with DIY again

 

[Coelomate]

I always thought that in one battery models it might be cute if you actually put in a compartment that held mints.

The look on somebody's face if you actually offered one from the tin with the wires poking out would be classic

 

[Nospam]

I like that idea, although I'd be a little concerned with mint debris getting into everything.

Now, if I could come up with some sort of self-sealing compartment...

 

[Coelomate]

haha... talk about over engineering - building a mint tin for a mint tin

Anyway, that's a valid concern - I'd forgotten I had to wash out my tins before puting the electronics in.

Well - are altoids conductors or insulators?

I bet you could fit one of those little breath strip holders into it?

"Oh, this altoids tin? No, it doesn't have any altoids, it has menthos breath strips. The wires? Well, it's complicated..."

 

[tangent]

Quote:

Originally Posted by Nospam I'll be using the AD Op-Amps which don't need much voltage.

ADI chips aren't special in this regard...they're all over the map. Which ones in particular will you use?

Quote:

So, if I use the Altoids tins, is it still worth it to wire the batteries in series?

If you can't hear a difference, and the chips will work down to the minimum useful voltage of your battery (1.1V x number of cells for NiMH, in my experience) then no.

Quote:

Put in a recharging circuit. Add a power jack for non-portable applications.

These are a single item, actually, or should be considered so. It won't take a whole 9V worth of volume, though, because about the only thing that makes sense for 9V NiMHs is a basic trickle charger.

Quote:

Get rid of the power switch and see if the switching Pot can fit.

Certainly it can:

Quote:

Any other ideas?

Use a set of prismatic cells, and add that recharging circuit. This will give you more mAh.

If you're using a truly low-voltage op-amp, use 4xAAA.

Quote:

Well - are altoids conductors or insulators?

Cinnamon Altoids and regular Penguin mints are insulators. You want to know the answer for any other type, all it takes is an ohmmeter.

 

[Nospam]

Quote:

Originally Posted by tangent ADI chips aren't special in this regard...they're all over the map. Which ones in particular will you use?...

I'm planning to use the AD8620AR, I think.

Thanks for all the suggestions. So many choices, so little time...

 

[Porksoda]

Quote:

Originally Posted by tangent Cinnamon Altoids and regular Penguin mints are insulators. You want to know the answer for any other type, all it takes is an ohmmeter.

I believe the peppermint altoids sound the best. I noticed a slightly expanded soundstage, and more liquidity in the mids.


EDIT: As for a charging circuit, you can EASILY pack a stripped down version of the PPA fast charger into that ammount of space if you do some creative board folding. I used two pieces of protoboard folded back to back to fit a charging circuit into my pimeta a while back. Check it out:

The charger is standing vertically just to the right of that green AA battery, with the LM317 mounted to the floor of the case. The circuit was pretty much right off of the MC33340 datasheet, which is pretty simple. The only reason Tangent's is more complicated is because it is designed for higher voltages, like say 18 volts or more. Since you are only charging 10V or so, you can use pretty much the datasheet schematic, and power it with a radio shack wall wart or a TREAD if you are feeling ambitious.

2nd Edit: Just for the record, I have since cleaned up the wiring in there

 

[tangent]

Quote:

Originally Posted by Porksoda I believe the peppermint altoids sound the best. I noticed a slightly expanded soundstage, and more liquidity in the mids.

True, but for deep, rich bass, you can't beat chocolate Penguin Mints.

 

[Sinbios]

Quote:

Originally Posted by Porksoda I believe the peppermint altoids sound the best. I noticed a slightly expanded soundstage, and more liquidity in the mids.

I found that covering the circuitry in cinnamon altoids dust makes the sound crisper and sweeter!

A new line of mods?