Inexpensive LiPo low voltage audibel alarm

[TriChrome]

One of my team mates showed me this product. Says it's TSD brand, but says "intellect-battery[.com]" on the product so they probably buy them from intellect and redistribute it:

http://hotspotairsoft.com/catalog/product_info.php?cPath=85_89&products_id=2720

Does anybody know if you can plug this into your battery's balancing plug while you're using/shooting the gun? I need something inexpensive to warn me when the batteries voltage is getting low, and this seems like it's incredibly small, and cheap. Any other options are welcomed (and sorry Wolfdragon, I would need 5 of yours so that's not cost effective for me and not all my guns have MOSFET's in them to hook your board up to).

[FiveseveN]

If you want to make one yourself, look here
http://www.rcgroups.com/forums/showthread.php?t=221018

You should be able to just plug it in the the balance plug while using the main connector.

[wolfdragon]

lol yeah, mines not designed with loud noises in mind, i like to be the crazy guy that makes people say *^*&^&(^! where the &*&^&$% he come from?!

as for an easy circuit, that micro scream is OK, but make sure you use tight toleranced resistors (.5% or less) as that circuit basically makes some fun happen with bias currents

it is a very tricky and possibly false alarmist for our uses considering that we use full bore drains following an insane burst current that will briefly lower the pack voltage can cause that circuit to chirp

an RC circuit with a time constant of a few seconds would help clean that one up, but even then, the tolerances of the reg plus that FET can add up to a board that alarms early or late, not very settable and if you used variable resistors you will drive yourself crazy with the tuning

give it a shot and see, im trying to get the cost down on my boards as best as i can but i cant get components for much cheaper so maybe a redesign isin the future?

[wolfdragon]

after playing around with my basic PCB design, I can make one that is a "Lite" version

it won't be compatible with the SW-______ types of MOSFETs so theres one limitation

but, i am fairly certain i can get it at or maybe below 15 USD

advantages over that RC one

1. hard coded limits that have error checking so droops dont cause alarms
2. no false alarms due to value tolerance issues
3. no fuzzy areas, will trip when it is supposed to trip, no exceptions

Being 100% digital, it and all of it's brothers will perform the same, each time, every time, resistor tolerances simply won't do that

basically its a very stripped down code version of what i already make, it will have one LED for telling you how many cells the board sees at startup (and possibly a battery low indication on the same LED) and EITHER a LED for dead battery alarm or a peizo buzzer


I can play around with the idea on paper butI won't get around to actually making a couple for protyping unless I see some interest for it.

I will even make the power configuration for it universal so you don't have to change anything but how many wires you solder onto the side of it for the pack to use different voltage packs


any interest?

[AIX]

it is a very tricky and possibly false alarmist for our uses considering that we use full bore drains following an insane burst current that will briefly lower the pack voltage can cause that circuit to chirp

I can vouch for this.. I've got one running in one my M4s...  Lots of chirping on semi-auto.

[wolfdragon]

lol yeah i would probably use a nice fat capacitor to keep the power steady for the regulator


looks like it would be a 15USD board, approx the size of a quarter, everything but the piezo alarm would be super low profile so it could be jammed nearly anywhere, I would most likely have the buzzer on some leads so you could put a 2 pin disconnect on it, put a small hole in tehside of your AEG and glue it in somewhere nice, then when you wanted to remove the board for whatever reason you coudl just unplug the buzzer


just pondering possibilities, i've got a basic layout and revision to the code right now, if desired i could probably get these to a production state in 2 weeks (assuming that i cleaned up the code and finalized the layout, not hard, just something that needs to be done)

[TriChrome]

I would order 4 of them right off the bat. No lights needed for me, just an audible alarm so when the unit is hidden inside the gun I can hear it when the voltage is low.

[mateba]

Wolddragon, HELL YEAH! CHEAP DUMMYPROOF LIPO SETUPS!

[wolfdragon]

LOL alright I will get a partslist and board layout done and get the first round of parts coming on Monday with the rest of the stuff I need from them

[TriChrome]

I will anxiously await the new product (and will tuck away a little bit of my paycheck to pick some up

[DyNo!]

The chirping got annoying and I use my mind (and an volt counter) to monitor the voltage on my lipos.

[wolfdragon]

which is why (and how my programming will do it too) i would make it not make noise until it was really time and not just a bad droop caused by the AEG firing

well TriChrome, looks like Sunday is finalized design day, already found the necessary bits to shrink it down and get everything happy

[TriChrome]

well TriChrome, looks like Sunday is finalized design day, already found the necessary bits to shrink it down and get everything happy

Great. You work fast. When they're ready to ship send me a PM and we can work out payment details.

Also, can you confirm they will fit inside the stock of an M4? (about 24mm diameter). That's where I'll be using most of these.

[wolfdragon]

i will keep whatever dimension you want in mind but i will do my best to make it as small as possible, is the stock inside a 24mm diameter cylinder?

[TriChrome]

i will keep whatever dimension you want in mind but i will do my best to make it as small as possible, is the stock inside a 24mm diameter cylinder?

Yes, and I'm just being selfish since that's where I store all my batteries and MOSFET's (have no other choice on the popular M4 platform with RIS's; there's barely room inside them for anything). And you said around the size of a quarter which is 24.3mm, and a standard M4 buffer tube is only 24mm in diameter, so I thought I'd clue you into that.

As small as possible is always best of course, as I'm sure people will be using these in extremely tight spaces (which is where people usually use LiPo's instead of Ni-Mh), but we all know there's a bunch of components to this alarm so it's not going to fit on the head of a pin (but if you ever build one like that let me know

I'll also have to take some shots of the balancing plugs on my batteries... I hear there's two popular types and I have no clue what mine are. EDIT, here's the pic:



Seems like I have 1 of each type.