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Re: Sneak preview of the new χ1 Li-Po battery board

PostPosted: October 5th, 2011, 10:16 pm
by goldkenn
Then maybe I tell "should be within this month", since people always think I should know some insider news and keep asking........

Re: Sneak preview of the new χ1 Li-Po battery board

PostPosted: October 6th, 2011, 5:21 pm
by Rustybutterkniv
Hey, just wanted to say thanks for your creativity and committment to the hobby. When I built my Mini^3 I ended up reversing the battery contacts and needing to resolder. I must have done a rather bad job while removing the solder, because there wasn't much of anything left for the contacts to adhere to on the board after resoldering and readjusting a couple times. I ended up having to run hookup wire from B+ to D4, and the positive battery contact has always been a bit loose because only one of the anchoring pads for positive is still good. Lately I've been running it straight out of the wall, no battery.

Anyway, the X1 project is perfect for me. I was thinking about getting a totally new board, batt contacts, and op-amps (among other things that might need to be replaced going to a new board), but if I can get longer batter life, faster charging, for about the same price.. I'm jumping on that right away! Dunno if anyone else has suffered the same problems as I have, after reversing the NiMH contact polarity, but it's definitely an option.

:D

Re: Sneak preview of the new χ1 Li-Po battery board

PostPosted: October 10th, 2011, 1:54 am
by point1
Nice Project. I will probably build one as well…

In the "old" Mini³ stereo pocket headphone amplifier design, the rail splitter is needed to create a virtual ground. With this x1 Li-Po update, there will be a real ground available. Are there some other advantages I don't see in this virtual ground? I assume, a passive ground will be more stable.
I see your argument of not changing the amplifier board. Makes perfectly senses.
Just in case you would design a new amplifier board, with the x1 Li-Po supply, would you still use the rail splitter design?
Could I remove the virtual ground (remove U3 and U4) and replace it with the Li-Po mid point? Would this work?

I’m not criticising, just wondering

Re: Sneak preview of the new χ1 Li-Po battery board

PostPosted: October 10th, 2011, 12:53 pm
by amb
There are a couple of problems with using the node between the two Li-Po cells as "real ground" in the Mini³.

First, the amp is powered on and off with a single SPST switch (integrated with the Alps RK097 pot). When you turn off the power, it disconnects V-, but not V+. In the virtual ground design, it's not a problem because when V- is disconnected, the TLE2426 rail splitter also loses power and the whole thing collapses together. If we use the node between the two cells as ground, when the power switch is opened, V- collapses but V+ is still "live" relative to ground and the output will likely emit a loud pop and produce a nasty DC offset.

Second, the UCC3911 protection IC on the χ1 battery board works by disconnecting the batteries from the load via an internal FET on the V- leg. A similar situation as the power switch above would occur if the chip decides to cut out the battery due to, e.g., over- or under-voltage conditions.

Re: Sneak preview of the new χ1 LiPo battery board

PostPosted: October 21st, 2011, 2:01 am
by amb
The day has come! χ1 v1.0 is now released and shipping.
The official χ1 website is also now online.

Re: Sneak preview of the new χ1 LiPo battery board

PostPosted: October 21st, 2011, 7:22 am
by jtktam
amb wrote:The day has come! χ1 v1.0 is now released and shipping.
The official χ1 website is also now online.


:two thumbs up:

Re: Sneak preview of the new χ1 LiPo battery board

PostPosted: October 21st, 2011, 10:16 am
by bcg27
amb wrote:The day has come! χ1 v1.0 is now released and shipping.
The official χ1 website is also now online.


Congrats on the successful completion of yet another project!

Re: Sneak preview of the new χ1 LiPo battery board

PostPosted: October 21st, 2011, 1:03 pm
by Rustybutterkniv
Congrats on finishing this!

I just have a quick question. I have a Radioshack regulated AC Adaptor for 3-12 V (including 9V) at 1 A. This is Catalog Number 273-029. It appears that RS has switched over to 273-316, with similar specs since I bought that one. I'm wondering if this would work for charging the X1, and if so, you could put it on the parts list.

Here's a link:
http://www.radioshack.com/product/index ... Id=3875403

Re: Sneak preview of the new χ1 LiPo battery board

PostPosted: October 21st, 2011, 2:21 pm
by amb
The 372-316 specs doesn't say whether it's regulated. You can measure its output at the "9V" setting to see what the actual voltage is and if it meets the requirements.

I am using a Radio Shack 273-356, which is 9V regulated 1500mA and it works fine. Like most Radio Shack AC adapters, the output plug is sold separately -- you have to buy the right one (2.5mm barrel) and put it on for the proper polarity.

Re: Sneak preview of the new χ1 LiPo battery board

PostPosted: October 22nd, 2011, 6:29 am
by Coughinhk
Great work Ti and MrX ! I'm sure this is going to be a very popular.

Have you thought about using one of these batteries/charger to power an ldo like the adp150 to create a clean 3.3V supply for a XO ?

Anyway, my order is in - thanks again !