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** DIY tech tip :-) **


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#1 jimmyjimmy19702010

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Posted 28 October 2017 - 07:45 PM

Hi Guys & Gal(s),

Well I’m still refining the performance of my big boy V5.0 build. It’s been performing great apart from one issue.

The V5.0 suffers from a common issue called a ground loop that causes an annoying buzzing/popping noise that’s most noticible during quiet passages during music and movies (I ocassionally use the V5.0 as my home theatre centre speaker).

This issue is caused by the amplifier and BT receiver sharing a common power source.

Enter my latest EBay purchase: a 12 volt DC-DC Converter Isolated power module.
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Simple really - According to the schematic, power in (from the 12v SLA battery) - pins 1 (+) & 2 (-), power out via pins 4 (-) & 6 (+).

BTW, the seller doesn’t supply the schematic with the unit - it took a couple of messages to the seller for them to email me the info above.

I installed the module in the power supply wiring for the BT receiver:
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A little heat strink tubing later: :-)
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In place and ready to go:
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Success!! - no more hiss, popping, clicking or buzzing noises. Sounds like a modern BT pro box now! :-) It’ll add $5 to your build cost but trust me, it’s worth it!

eBay link: https://www.ebay.com.au/i/401394723485

Have a great weekend guys,

James..... :-)

#2 Reli

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Posted 28 October 2017 - 08:24 PM

Guess I'm not clear. Where is the power in from, and the power out to?



#3 jimmyjimmy19702010

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Posted 28 October 2017 - 08:51 PM

Guess I'm not clear. Where is the power in from, and the power out to?

Power is in from the 12v SLA battery and power out goes to the Coast BT receiver. :-)

#4 Reli

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Posted 28 October 2017 - 11:29 PM

And if the boombox is 15V?



#5 jimmyjimmy19702010

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Posted 28 October 2017 - 11:35 PM

The module can handle 10-16 volts so you’re all good. The specs say 12 volt out but after testing, it appears that the voltage out matches the voltage going in. :-)

#6 Northerner

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Posted 29 October 2017 - 02:16 AM

Interesting. I know this is a big problem on some BT conversions. I'll keep that item in my eBay watch list. Thanks for the tip :-)

#7 Reli

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Posted 29 October 2017 - 12:27 PM

The module can handle 10-16 volts so you’re all good. The specs say 12 volt out but after testing, it appears that the voltage out matches the voltage going in. :-)

 

For them to say "12V out" seems odd



#8 jimmyjimmy19702010

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Posted 29 October 2017 - 01:10 PM

The module can handle 10-16 volts so you’re all good. The specs say 12 volt out but after testing, it appears that the voltage out matches the voltage going in. :-)


For them to say "12V out" seems odd
Well just use it on 12v boxes. All my builds are based on 12 volt componentry as it’s a standard format.

#9 Reli

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Posted 29 October 2017 - 02:05 PM

Looking at Ebay there's lots of choices, you can select your input and output voltages, you can even get more voltage out than you put in. 

 

I guess the watt rating doesn't need to be very high since this is just intended for a Bluetooth receiver



#10 trippy1313

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Posted 01 November 2017 - 04:05 PM

I like how it's labeled "GODSEND." Hahaha.

#11 Superduper

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Posted 02 November 2017 - 07:26 PM

I guess the watt rating doesn't need to be very high since this is just intended for a Bluetooth receiver


Watt rating on Bluetooth receivers don’t need to be too high but does need to have enough juice to operate satisfactorily. The thing is that this godsend chip didn’t even include a current rating. Is 100mA enough? Because a single old school tuner dial incandescent bulb could consume 80 mA. Bluetooth receivers need to output audio signals in stereo, and have enough RF power to communicate with the transmitter.

#12 jimmyjimmy19702010

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Posted 02 November 2017 - 11:28 PM

The BT receiver works exactly the same way it did before the mod (same range, quality etc).

Just no more strange noises. :-)

I’ve requested the wattage of the module from the eBay seller.

#13 jimmyjimmy19702010

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Posted 03 November 2017 - 04:58 PM

After a night of extensive, near maximum volume cranking over a 3.5 hour period, the performance of the BT receiver has been flawless with regards to sound quality and range.

You can literally turn the amp volume pot to max whilst connected to a paused BT device and have zero hiss/buzzing noises from the speakers. I know this doesn’t sound like a big deal to most but anything that improves sound quality is important. Its a big improvement on what I have been able to achieve without this module. It’s a ‘Godsend’ :lol:

So the receiver doesn’t ‘appear’ to be starved of adequate power with this module. This of course only applies to the Coast receiver used in this build. :-)

I certainly wouldn’t suggest anyone to utilize this module to power a high draw component like an amplifier or USB charging outlet.

James..... :-)