The Boominator - another stab at the ultimate party machine

[Cooldox]

Hello again, and thanks for your previous responses.

As mentioned earlier, we are pretty sure we fried our AMP6-Basic in the months of storage our Boominator endured after Roskilde Festival this year. It was left in a decently-lit room for approximately a month, with our 10W solar panel constantly charging our two 7,2 Ah SLA batteries. The voltage on the batteries now is now 0.3 volts, and well beyond repair (as far as we've read on the internet).

To be honest, we can't really figure out whether the batteries have been drained completely or overcharged and boiled dry. Nonetheless, we've bought a new pair of batteries and a solar-charge controller, and are now looking entirely on the AMP.

Our amplifier makes absolutely zero sound. No hiss, no clicking. Nothing. We'd love to be more specific about what is wrong, but we have no clue.
We've of course attempted to diagnose it ourselves with the assembly instructions, but our attempts have been non-conclusive. As the assembly instructions specify in the "troubleshooting" section of the manual, we've tested the following.

• "Check if you have 5V over C2. " - We measure 0 volts.
  "Check if you have about 1.2 V over R7" - We measure 0 volts.
  "Check if you have about 10 V over C5" - We measure 0 volts.
  "Check if you have about 2.5V to ground" - We measure 12 volts?..

What could have happened to our amplifier? How can we measure what exact components are (if that's the case) fried?
What can we do to diagnose our AMP?

Thank you very much in advance.

[Saturnus]

Originally Posted by Cooldox

"Check if you have about 1.2 V over R7" - We measure 0 volts.

What could have happened to our amplifier?

The input of the chip is fried if it reads 0V. You need to replace the chip.

[Cooldox]

Originally Posted by Saturnus

The input of the chip is fried if it reads 0V. You need to replace the chip.

Well that settles that. Thank you so much!

It seems 41hz.com is out of stock of the Tripath TA2020. Do you know of anywhere else to buy another chip?

I already found a thread with a similar question on diyaudio, but neither profusionplc or 41hz have any in stock.

[Saturnus]

e-bay

[larzman]

Originally Posted by Kasper Jack

Looks fine to me, apart from two things.
I don't know if a 12v voltmeter will suffice, I think SLA's exceed 12v when fully charged, but I am not sure.
You might want to place the tweeter cables and resistors in the electronics compartment, in case you want to replace them one day.
Well that's just my ten cents

You can get a digital voltmeter (3.5 digit) that does up to 19.99V from Deal Extreme for about $7. I use it on my solar boombox. I chose to attach a double-pole, momentary contact switch so I could see charge level of the battery as well as solar panel output (to help adjust panel position). Use a momentary contact switch, with normal position turning the display off, this helps keep the battery charged, and you most likely only want to check voltages for a few seconds every now and then.

Even a "12 volt" solar panel will put out about 18+V when in the sun. I use a 20W monocrystalline panel that pushes 19+V in bright sun. Monocrystalline panels are the best, more power produced for minimum size. My mini-sized boombox version will use a pair of 12V 5W panels affixed on a hinge and/or detachable on the back of the speaker boxes. Amazon has good, cheap monorystalline panels and connectors. Make sure you use a charge controller between the panel(s) and the battery(s), or bad things will happen.

[larzman]

Originally Posted by danielwritesbac

Fiercely Bright nonstop sunlight, or. . . dual power
Put TWO low voltage schottky diodes into the input + port of your charge controller.
The diode's stripe goes closest to the charge controller.
Connect the solar cell to one of the schottky.
Connect laptop charger (SMPS) to the Other schottky.

Solar >| Charge controller
SMPS >| Charge controller
(One charge controller, two diodes, two sources)

Now, when the laptop charger (SMPS with inbuilt overcurrent protection) is plugged into mains, your battery will charge, efficiently, in less than 1 hour. The charge controller's indicator lights will tell you what's going on.

P.S.
Other way: Wallpaper the Boominator completely covered in solar cells.
I say this because a modest size solar cell may prevent draining but isn't enough for reliable charging.
P.P.S.
Buy a Multimeter and utilize the DC voltmeter function to confirm battery charging is working.

I beg to differ about the solar panels Daniel.

I have a proof of concept solar boombox thats a little over a year old, powered strictly by a 20W monocrystalline solar panel (23.5" by 12"). My next version will have a smaller (physical size) pair of 10W panels. From usage experience and theoretical calculations based on real-world measurements, my boombox can run for about 3 years, 24/7/365, at a little over half volume on a SI amplifier and 92dB efficiency 8" speakers. This is quite loud, although nowhere near Boominator level, but great for a patio party with friends. The limitation to longevity is the number of charge cycles a typical SLA/AGM battery can handle, around 1,000. About any charge controller will most likely have a charge/load limiter, reverse diode and OV/UV protection circuits.

A well designed solar power system can easily power a high-efficiency boombox. Be smart about the choices of solar panels, charge controller, and audio hardware and you get a very efficient system.

[danielwritesbac]

Originally Posted by larzman

I beg to differ about the solar panels Daniel.

I have a proof of concept solar boombox thats a little over a year old, powered strictly by a 20W monocrystalline solar panel (23.5" by 12"). My next version will have a smaller (physical size) pair of 10W panels. From usage experience and theoretical calculations based on real-world measurements, my boombox can run for about 3 years, 24/7/365, at a little over half volume on a SI amplifier and 92dB efficiency 8" speakers. This is quite loud, although nowhere near Boominator level, but great for a patio party with friends. The limitation to longevity is the number of charge cycles a typical SLA/AGM battery can handle, around 1,000. About any charge controller will most likely have a charge/load limiter, reverse diode and OV/UV protection circuits.

A well designed solar power system can easily power a high-efficiency boombox. Be smart about the choices of solar panels, charge controller, and audio hardware and you get a very efficient system.

Thanks! Amazingly timely too.

Maybe there is an easy solution.
What do you think about 4 of "non glass" 5w solar panels, each with 14v zener directly parallel with and mounted on the individual solar panels; also, each solar panel has a series schottky inline with its own cord so that if a leaf lands on one solar panel, the rest still work? 13.8 zener load subtract 0.3 series loss of schottky = 13.6vdc charger. . . actually 4 individual 13.6v chargers. Well, it can't either overcharge or drain.

I did that to an RV, except with 15v zener's parallel with each solar panel, and yes each 5w panel has its own schottky in-line series with the cord in case a leaf lands on one of them (a leaf is all it takes to turn a useful solar panel into a counterproductive resistor, so this is why each panel has individual schottky outputs). Well, 14.8 subtract 0.3 schottky is 14.5v like a car alternator voltage.
4 of 5 watt panel is only barely enough solar panel wattage to give the huge battery a boost to 12.8v on a cloudy day; however, it is so much better than a dead battery. The battery stays charged well enough that the generator will start eagerly if AC is needed; however, the typical need of lighting is accomplished with led's and that gigantic battery.
Cost reduction? $40 per month less on the electric bill because of unplugging the RV.

It seems to me that the advantage of that cruder zener diode-based charge control is that there's no charge controller battery monitor to slowly drain and irreparably break the battery if the boominator is stored in a dark closet for months because the manufacturer of the charge controller assumed roof mounted panels, not dark closets. So, by controlling 5 watt panels with simple zener didoes on the panel, see how both the solar panel and the voltage limiter is isolated from the battery by schottky diode? Can't drain. Nice!!

What do you think of that?

[joeoz]

Hi there,

Hoping to build a boominator or qubinator at some stage (need one to take to the beach, camping, etc. this summer). The amount of useful information in this thread is overwhelming. Well done Saturnus and the others for this fantastic project.

A regular theme here has been about boosting the signal from iPods, MP3 players, etc. to get the most out of the amp being used.

I recently put together one of these very simple preamps for under $10:

http://beavishifi.com/projects/Passive_IPOD_Preamplifier/

Did some simple tests, using a small el-cheapo MP3 player connected to a TA2024. I did some quick comparisons with, and without this preamp connected, and there difference was quite noticeable.

On a separate note, probably not relevant to boominator usage, I noticed much less noise when using the preamp, which was only an issue because I had the MP3 player connected to my laptop via USB (I was charging it). The preamp lowered the hissy noise substantially, which I guess is an added bonus...

Not sure how much gain this preamp provides, but it might be worth trying for those who don't have an easy way to adjust the gain on their amps via the resistors.

A pair of transformers, a simple project box, with 3.5mm stereo jacks on each end. A nice (and optional) non-intrusive way to get some extra gain.

Anyone tried this on their project?

Cheers,
Joe

[larzman]

Daniel,

Sounds good, but I would simply use a charge controller as any I've seen or designed always had the reverse diode. Heck, a lot of panels have one (diode) built inline with it's output wires. It also protects the battery from overcharge or overdraw. Both of those will seriously shorten battery life or worse.

On my 5W mono solar panels, which are only 10.5" by 8.75", a leaf would need to cover 20% of the panel to decrease power by 1W, not too realistic considering the panel should be at least somewhat vertical. If one is going to store the panels/controller/battery in a closet, probably best to unhook the panels entirely.

In the end, that's where you have to live with your design choices. I went through some extra trouble/time to make things work good for me. This included using detachable connectors for all devices and putting switches in key places, e.g. volt meter. It's also wise to add fuses at several points, especially in the battery connections. Some good planning and you can inexpensively make a very reliable, sun-powered, power supply to suit your needs and it will power a portable boombox to deafening levels, without the need to replace batteries (at least not very often) and no power cord.

[larzman]

Joeoz - I like the sounds of your passive preamp idea. I looked at the circuit on the link you provided (thanks) and it's super simple to build. However, I'm wondering about the audio quality after running through a transformer rated at 300~10kHz. How does it sound? Are the bass and high notes subdued? Would a better transformer help?