M70 & M90 with hardwired bluetooth module mod.

HRmeteohub

HRmeteohub

Member (SA)
Mar 19, 2017
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Okelly said:
^ I believe it's about keeping the integrity of the box but updating to be used with today's technology. I personally would love to have all my boxes setup with Bluetooth and have them look factory because I don't see myself making tons of cassettes of new music just to use the box. The phone I carry on my pocket has unlimited music.
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I second that.
Although the blue LEDs can look nice, they can also scream: " I was different!", or perhaps:" I am Frankestein!".
Somehow I do like the incadescent lights, and I tend to replace the bulbs or if not possible, put similar LEDs instead.
While we are at it, that is a nice looking boombox!

What are your thoughts about SD card MP3 players with remote controls or RaspberryPi based media players (WiFi connected and probably wth remote control or touch screen)? I mean, when in Rome... why not go all the way?
 
HRmeteohub

HRmeteohub

Member (SA)
Mar 19, 2017
138
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Croatia
Reading this thread it seems to me that people do not know that it matters a lot what kind of BT dongle they use. There is rather good text on Wikipedia. Specifically, the range depends a lot on what version of BT standard is used. Range alone goes from 10 m to 240m (33 ft to 800ft).

So, If you do not need 100 m /330 ft, go for $2 BT v2.0+EDR and it will do fine. Of course that v3.0 or v4.0 will work better...
 
dan

dan

Member (SA)
Apr 6, 2019
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trippy1313 said:
Let us know how well it works, and take pics and details of the install!
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well, i installed the BT module and it works but i'm getting high frequency noises after the bluetooth module connects. don't think it's a ground loop, positioning of the module or routing of audio wires. everything is fine when the unit is powered off a power source that doesn't come from within the radio such as a battery or usb charger connected to the wall outlet. i'm powering the unit off the X505 power rail via the the lamp power line with a 5 volt LDO regulator. the regulator isn't causing the noise either. it seems like high frequency switching noises are coming from within the BT module and feeding back through the BT module's power connection and into the M70. it's annoying if you have the volume cranked up with no audio signal. the noise is also present on other input selections if the BT module is powered on.


i wonder if this would help with the noise. it is a DC to DC isolation module:

B0505S-1W

https://www.mornsun-power.com/uploads/pdf/B_D-1W.pdf

https://www.ebay.ca/itm/NEW-B0505S-1W-DC-DC-module-power-module-isolation-module-SIP-4/201415049948?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

provides 200mA of current max. must have a load of at least 20mA to operate correctly. some passive components required, 4.7uf cap on input and 10uf cap on output. it has a max capacitive load of 220uF. my bluetooth module has 2 100uF caps on it plus all the other nF caps. i wonder if it would be pushing it close to the operating tolerances.

here are some different units from digikey:

https://www.digikey.ca/product-detail/en/recom-power/RM-0505S/945-1206-ND/2256386 50mA out


https://www.digikey.ca/product-detail/en/recom-power/ROL-0505S/945-1949-5-ND/2315051 100mA out


https://www.digikey.ca/product-detail/en/recom-power/RFM-0505S/945-3159-ND/8550767 200mA out


these can operate with a capacitive load of 470uF max.
 
trippy1313

trippy1313

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Jul 16, 2013
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Did you take pics of the install? What I've found with the module I used was to use the ground for the module but don't connect the negative side of the audio outputs. With the module I used, the shared the same ground, so connecting the audio ground made the loop noise.

I think I also found to connect to module ground to the main chassis board ground on the radio, if that makes sense.


Also, test out the range, let us know what kind of connectivity distance you get.
 
dan

dan

Member (SA)
Apr 6, 2019
65
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trippy1313 said:
Did you take pics of the install? What I've found with the module I used was to use the ground for the module but don't connect the negative side of the audio outputs. With the module I used, the shared the same ground, so connecting the audio ground made the loop noise.

I think I also found to connect to module ground to the main chassis board ground on the radio, if that makes sense.


Also, test out the range, let us know what kind of connectivity distance you get.
Click to expand...
i took some pictures and will post when i finish. i tried disconnecting the audio ground but it didn't help. i don't know why there would be a ground loop. usually that happens if the grounds are not at similar potential. the ground for my audio and the ground for the BT module have no resistance between them so they should be at the same potential, unless the BT module is doing something inside its self that is causing a difference. the module can either be powered from the unit with audio disconnected or powered externally with the audio connected. power from the unit and connect the audio and weirdness happens, you hear those digital switching noises. i'm gonna get those DC to DC isolators from digikey and power the BT module through that and see what happens. i'd rather go that route than use a ground loop isolator on the audio because those things tend to affect the sound, they tend to kill the bass is my experience. the DC to DC isolator is smaller and cheaper and hopefully provides galvanic isolation which should eliminate any loop issues or interference feeding back through the power lines from the BT module. it should essentially be the same as running the BT module from a separate battery.

p.s, i ordered xy-bt-mini modules from a place, i blew those in my experimentation and ordered another 5 from the same guy. they arrived the other day and i received hw-770 modules which look exactly the same. the only problem is that the hw-770 have a heavily chinese accented english language voice instead of the tones on the xy-bt-mini. i prefer tones over people talking.

i gotta see if they have any BT modules that are made in italy. i wouldn't mind super mario telling me my blue a tootha is a now a connected. ;)

p.s, on the BT module, i measured resistance between the negative power terminal, audio ground and the pcb antenna and there is no resistance between these points. i wonder if this is the issue. if the antenna is connected to the ground, then the BT signal would feed back through the power ground and audio ground. if the BT module is powered by an external source, the BT signal would be part of a different electrical circuit and wouldn't feed into the M70.
 
dan

dan

Member (SA)
Apr 6, 2019
65
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UPDATE: 6/11/19

success! the dc to dc isolator works. no more RF signal noise. the sound quality is also excellent now. it seems like range is also a bit better.

the isolator adds around 35-40mA current usage to the circuit. i think it has a quiescent current of about 20mA and is around 70%-80% efficient. my lighting and BT use around 110mA when everything is on. it's all on a 250mA fuse just in case something goes nuts it won't take out my x505 rail.
 
trippy1313

trippy1313

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Jul 16, 2013
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Did you get a chance to test the range and quality of this newer module?

I'm curious if the BT 5.0 range is really as good as its supposed to be. Supposedly around 150-200 feet I think.
 
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