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The art of Sen

Interesting battery facts
I would try regulated supplies but think it’s wise to give battery a go as there have been some clues to using battery for Sen
 
This might be just the ticket. Bit overkill on capacity but quite cheap :p

Stefan
 
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Have I missed something Stefan, they look like £200 for four banks, over twice the cost of AAA NiMh
 
I'll defer to your experience on this Stefan - my experiences relate to their use in caving lights and, touch wood, in that application they seem to be very reliable (not that I go caving any more, sadly).
 
Have I missed something Stefan, they look like £200 for four banks, over twice the cost of AAA NiMh

Ah, they are, I meant for what you get, balancing and battery management system and LOADS of capacity, you wouldn't need to recharge very often at all. If you broke the cost down to hours of use until failure i think this kind of cell is much cheaper than NiMh.

There are smaller capacity ones on the 'bay similar to a typical AA capacity which are much cheaper, these for example.

Might be worth noting that most of the BMS (battery management) systems which are necessary are designed for 4,8,12 or 16 cells when we need 6.

Stefan
 
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or from the same site Ansmann ones which would come in at £78 - more expensive but VERY good batteries at more than twice the capacity. Still a bit worried about failure of NiMh though, i'f one failed would there be damage to the SEN circuit?

Stefan

Ignore my crappy math above, I was still working on 3.2v cells not the 1.2v of the AA cells - the Ansmann ones are about £200 Gulp.
 
These really are a bargain. It'd be less than £50 for the cells, they should really be used with a balancing circuit though.

Stefan
 
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Or these from the same e-bay seller, same 1000mAh capacity but a far smaller form factor which might make them easier to get in a box !!

Less that £25 too ;)

Stefan
 
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Hi

(Suffolk) Tony- yes, batteries are essential. All Nic's efforts with mains powered supplies were sonic failures. This isn't because batteries have some magical properties- I avoided them for years- just that connection to the mains introduces noise which is detrimental to the SEN/CEN circuitry. Mains power seems fine for the digital circuitry- though I will try a battery here too (probably a lead acid type of about 15Ah- too big for my case, as Buffalo + regs draws upward of 500 mA)

I think 4 x 4 blocks of AAA NiMH batteries- I used 900 mAh types- giving at least 20 h of operation- is the cheapest way of providing sufficient capacity. And Patrick has used this arrangement, with his simple charging circuit, for over 4 years ( I think) without any failures. Just buy 16 battery holders (4 x AAA, with lids). When wired together and stacked 4 x 4 they form a neat block


Have another look at my comments of the previous thread

http://www.pinkfishmedia.net/forum/showpost.php?p=1743371&postcount=1152

Don't over elaborate things- you may end up with a worse result!

Paul N

Just saw the post about the LiFePO4 batteries. I stand corrected - 4 x7 of those would be cheaper. No idea about sonics though, and you still need holders and a charger circuit
 
Red Wine Audio even use the LFP batteries for power amps! I'm thinking that LFPs could run an entire Buffalo-based DAC. In comparison to PH regs, etc., it could prove to be very cost effective, perhaps provide better sonics, and will certainly run cooler.

At the very least, I'm willing to put in some more research and even some experimentation.
 
Well now I have a headache.
Never heard of LiFePO4 Lithium, looks like a car number plate.

Can we still trickle charge them at C/40 like NiMh

Hint, I NEED some batteries soon.
 
LiFePo4 are very useful as they pretty much put out 3.3v (sounds like a common requirement ;-) )for most of a discharge cycle and genuine ones have a low internal resistance (a baby's handful of milliohms).

Difficult to get hold of genuine cells though because the manufacturer had a really lousy business model and - last I read - was on the skids. Lots of dodgy-heritage cells with an identity crisis around which probably don't measure as well or hold charge well or provide for a long operational cell life.

If I could be arsed with the whole charging cycle management thing, I'd be giving them a go (if I could get some assured genuine cells). insert a cell wherever you need 3.3v and stick a reg between a cell and anywhere you need 1.2v. But mains powered regs are just so much more convenient most of the time. And you can engineer a reg to suit a given application much better than a one cell fits all approach.

Mark
 
If I could be arsed with the whole charging cycle management thing, I'd be giving them a go

Mark

Thanks Mark
That's the LiFePo4 charging management in particular then not cells in general.

I was just thinking of just trickling NiMh sort of simple stupid like
 
Hi Nik, yes, sorry should have said as an interim get me going measure, the kits on the plank and powered so real quick dirty fix for charging, one worry less, one purchase less.

Sure to find a better use for the Placid later on though.
 
About to push the button on the battery pack
16 x 4 gang Battery holder RS 512-3568 @ £4.96 + VAT

I have a choice of cells, but going with AAA NiMh UK supply

64 x RS brand AAA NiMh battery,1.2V 800mAh RS 504-6051 @ £92.32 + VAT
or
64 x Energiser brand AAA NiMh battery,1.2V 800mAh @ £101.28 + VAT
or
64 x GP85AAAHCB4 GP ReCyko brand AAA NiMh battery,1.2V 850mAh @ £91.00 + VAT

RS brand should be trusted, Energiser is major brand but most expensive and the GP ReCyko is unknown to me but good price and 850Mah

Found GP ReCyko on ebay for £63.84

Any advice
Tony
 
Jfet Idss matching.

Patrick said:
The 10mA is a typical figure.
What I said in the article is that you do not want to swing more than 25% of bias.
So if you total current swing is say 8mA (as in ES9018), you want to have at least 32mA total bias.

For example, Nic uses a set of 2SK369Vs with Idss of around 17mA.
So two of them in parallel (Q1//Q2, or Q3//Q4) gives about 34mA bias, thus satisfying the above mentioned rule of thumb.

It is important that Q1 has about the same Idss as Q3, and Q2 same as Q4.
Furthermore to have minimum DC offset, Idss of Q1+Q2 should equal Q3+Q4.
On top of that Q1 and Q3 should be glued onto the same heat sink, so that they thermally track each other.
The same applies to Q2 and Q4.

Of course if Idss of alll 4 FETs are exactly identical, you can aloocate them randomly.
For all those who obtain JFET sets from us, they all have a table telling them which JFET to use in which position.
 
Here are the IDss of my 2SK369Vs and my thoughts to pairing

Left channel
First quad
16.89 Q1
16.89 Q3
16.90 Q2
16.90 Q4
Second Quad
16.91 Q1
16.92 Q3
16.94 Q2
16.95 Q4
Right channel
First quad
16.97 Q1
16.98 Q3
17.01 Q2
17.02 Q4
Second Quad
17.03 Q1
17.03 Q3
17.04 Q2
17.05 Q4

Any thoughts
 


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