I just used that electrical tape in a jar with its own brush to seal it up. Doubt if the USB or micro SD slot will work though. He just uses his cell any way for input. He shows it off to his friends and they can't believe the sound from his Walmart small garbage pail speakers. Prob plays for days with that 7.2 Ah batt and 3116 d2 amp?
Bt board similar to the plain board doc and u posted about. It has aptx and bt4.0 from eBay. It is likely 2-3 weeks from China, with the extra amps. I also bought a pair of the 8932 boards for play/comparison. Will likely mocup in foam board with wires outside to adjust xo and try different boards?
Would one of these perhaps work for the noisy BT modules?
Isolated Power Module DC DC Converter Input Voltage 9V 36V Output 12V 5W | eBay
VB1212LS 1W Isolated Power Module w 4PINS DC DC Converter in 10 16V Out 12V 1W | eBay
A decent source of a high quality CSR based Bluetooth receiver is actually the AmazonBasics receiver. Sound quality is superb, no interference or hiss to speak of, and the board can easily be taken out and mounted in your own enclosure. Only about 4x the cost of the Chinese ones, worth it if you value your time
http://www.amazon.com/AmazonBasics-...5717&sr=8-8&keywords=bluetooth+audio+receiver
Isolated Power Module DC DC Converter Input Voltage 9V 36V Output 12V 5W | eBay
VB1212LS 1W Isolated Power Module w 4PINS DC DC Converter in 10 16V Out 12V 1W | eBay
A decent source of a high quality CSR based Bluetooth receiver is actually the AmazonBasics receiver. Sound quality is superb, no interference or hiss to speak of, and the board can easily be taken out and mounted in your own enclosure. Only about 4x the cost of the Chinese ones, worth it if you value your time
http://www.amazon.com/AmazonBasics-...5717&sr=8-8&keywords=bluetooth+audio+receiver
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Thanks for the suggestion. I will keep that in mind if I have lousy results from the one ordered! There is just something about putting together a system for pennies that makes me smile when it all works out. Just completed a 9year old system with cornucopya horn with two 3" computer speakers for $5 pair and 2497 $3.50 amp and $1 thrift store PS brick that sound decent. For $10 all in it cranks it for what it is. Addicting!
TPA3118D2
Oh they put some effort in the layout, nice. Programming header avail on the backside. Will see how mine is performing. Actually hacked the firmware to the point that you can pear 2 devices at the same time + line-in with seamless switchover. Also have the ability to use it as an UsB sound card and hopefully I2S out.
For the isolated DCDC, you want to have a 5Vout module (guessing yours is working with 5V). For those MP3/WAV/FM boards, increasing the capacitance of the first filter cap is the way to go. You want to have lots of capacitance while having super low ESR to form a HF-reflector together with a ferrite. Will post a picture tomorrow.
Oh they put some effort in the layout, nice. Programming header avail on the backside.
Will see how mine is performing. Actually hacked the firmware to the point that you can pear 2 devices at the same time + line-in with seamless switchover. Also have the ability to use it as an UsB sound card and hopefully I2S out. For the isolated DCDC, you want to have a 5Vout module (guessing yours is working with 5V). For those MP3/WAV/FM boards, increasing the capacitance of the first filter cap is the way to go. You want to have lots of capacitance while having super low ESR to form a HF-reflector together with a ferrite. Will post a picture tomorrow.
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Yeah, always makes me smile to pull apart a piece of generic consumer gear and find something that has clearly had some thought put into it. The programming header on the back definitely topped it off, with all the pins labeled too, don't even have to follow the traces back.
Nice work on the firmware hacks, should be interesting. Something I have always wanted to do is figure out how to pair my phone with 2 recievers at once, and use one of them for left channel, and one for right channel, so you can have your speakers totally independent from each other wiring wise.
For the isolated DC-DC, something like this would probably work better then? Basically will have to regulate to 5V, then isolate with these.
2pcs B0505S 1W DC DC 5V Power Supply Module 4 Pin Isolated Converter New Z3 | eBay
Nice work on the firmware hacks, should be interesting. Something I have always wanted to do is figure out how to pair my phone with 2 recievers at once, and use one of them for left channel, and one for right channel, so you can have your speakers totally independent from each other wiring wise.
For the isolated DC-DC, something like this would probably work better then? Basically will have to regulate to 5V, then isolate with these.
2pcs B0505S 1W DC DC 5V Power Supply Module 4 Pin Isolated Converter New Z3 | eBay
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no the commercial stuff can be had readily > M.G. Chemicals Acrylic Conformal Coating II 419C-340G
I've used the Mil_spec stuff and its really nasty to apply and clean up E.g. Tolene based. hard as a rock tho.
watch out for all connector, pots, and switches if any. Do consider replacement of all hardware fasteners with stainless.
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It is pretty clear you have dutch ancestors
BTW this thread is going all directions but still it is nice to read.
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Yes, I experienced similar with two types of el cheapo USB-BT dongles. The problem is a pulsating current consumption of the dongle that produces audible noise voltage across the common GND return. So your options are
-power the dongle with an isolated DC-DC converter, as stated above
-in case of bridged outputs, add a symmetrical input
-or provide very short, central GND wiring.
I chosed the last option, i.e. there is an USB-connector on my small amp PCB that provides a nearly perfect GND-plane.
This gives a very low noise floor.
But if you insert some USB-cable in between, the GND-impedance rises significantly and noise becomes inacceptable.
You could do that but you will indeed add noise. Best would be to find a 24V linear PSU. That is an opinion from someone that hates switchers
Or find a very good 24V 5A or higher rail mount industrial switcher and build it in a nice case. You are lucky since 24V is a bog standard industry value. Those are often used in automation. Phoenix, Murr etc. Just make sure you check/replace electrolytic caps if you find s second hand one.
Or find a very good 24V 5A or higher rail mount industrial switcher and build it in a nice case. You are lucky since 24V is a bog standard industry value. Those are often used in automation. Phoenix, Murr etc. Just make sure you check/replace electrolytic caps if you find s second hand one.
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Fixing it:
Noise level amplitude were determined by scoping the rail.
Stock board is like:
+470uF low ESR:
If you go for R1=10R and C1 = 1000uF ESR = 20mR, you'll reach -51dB at 10kHz.
The module i have:
At stock configuration it is like (data transmission can clearly be seen):
With additional 560uF SEPC cap:
Changing the resistor to 10R:
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You will be adding noise, how much that matters is completely dependent on your sensitivity to it, and the decoupling on your amplifier board.
The most perfect DC supply on earth can be super noisy at the IC if there is poor decoupling on the load it is connected to. In the same fashion, the noisiest supply on earth can be made to be dead quiet at the IC with proper decoupling.
To me, the noise from the supply is really not a big deal as long as it is not completely terrible, because it is really the voltage right at the IC pins we care about.
**NOTE: Everything above is specifically for Class D, and even more specifically for the "chip amp" style ICs, like the TPA3118 discussed here. Class A or Class AB are much different.**
Mord: Thanks for the BT board details, will try some things out this weekend.