AMB Laboratories DIY Audio

[mikeg88]

Whoa...some cool options. It didn't even occur to me to look to Neutrik for such a product. Thanks AMB & MisterX!

Funny that some these products didn't come up in my search on Mouser...

[amb]

Update: Testing/development is complete and production boards have been ordered. Estimated arrival is about 2.5 weeks. I will be working on the website during this time.

For those of you who want to build one as soon as the board becomes available, if you order the batteries online (such as eBay) the shipping time may be 2 weeks or more, so you may want to start looking now. You need two 3.7V 600mAH lithium-ion polymer cells (Walkera HM-4G6-Z-37, HM-4#6-Z-34 or equivalent, for Walkera 4#3, 4#6, 4G3, 4G6 RC helicopters). These are commonly available from RC hobby retailers and online. The two cells fit perfectly in the Mini³ Hammond enclosure, where the 9V NiMH battery occupied. The size of the battery (each) is about 42mm x 25mm x 8mm.

Please do not substitute with other batteries even if they fit. The charging circuit parameters are tailored for the specified batteries.

I have a very small number of these batteries on hand, when the boards arrive you may ask me to add two of these batteries to your order, but it's on a first-come, first-served basis and may run out quickly.

[amb]

Some pics for your enjoyment:

[lampee]

Great work! As always!

[MisterX]

Pretty graphs?



(the bottom "graph" was snipped from the charge controller datasheet and included for reference)

[jtktam]

i am heavily involved in the RC car scene and depending on the quality of the individual cells, lipo need to be balanced every once in a while or else you will get a pack that is overcharged and a pack that is undercharged. an undercharge pack will swell and can be potential fire hazard.

the hard plastic cases used by cameras and such prevents this type of swelling some what but there is still risk. there is lipo cutoff circuits that will "stall" the car a few times to let us know when it's running pass the danger low voltage cut off.. maybe something similiar.. cycle the amp when the voltage is running low

search for lipo fires on youtube...

-joe

[amb]

The UCC3911 protection chip on the χ1 board monitors the two cells for balance. If they become badly out of balance it will shut off the circuit.

[MisterX]

Discharge cycle/battery runtime graph.

[jtktam]

The UCC3911 protection chip on the χ1 board monitors the two cells for balance. If they become badly out of balance it will shut off the circuit.

what do we do after it shuts off? is it possible to use a "normal" JST male balancer port on the x1 so that I can use my balancer instead of the screw terminals?

-joe

[amb]

what do we do after it shuts off?

See the UCC3911 datasheet (page 7, under the "Application Information" section, "state machine operation" sub-heading). Texas Instruments recommends discarding the batteries (and replace with news ones) if they become that badly balanced.

It goes without saying that when replacing the batteries, you should not mix old and new ones.