No.058 - Vintage Sharp GF-6060 Ghetto Blaster Bluetooth Conversion

[@TheDefpom]

I suggest adding some series ferrites to the supply wiring and audio outputs to the bt module to stop the digital noise back feeding the supply, also add some tantalums to it, maybe also try using screened cable for the supply, digital noise is a pain to get rid of sometimes, I had issues with it on my CB PLL replacement board, in that case the noise was from the multiplexed 7 segment display driver and was radiated and picked up by the VCO/mixers.

[@ericgee6585]

I had lots of noise problems too, all were cured by ferrite rings on the BT audio output leads :)

[@IanScottJohnston]

I have fixed the noisy bluetooth module with an isolated DC-DC (0505) converter after the 7805 regulator, and wiring the supply to the 7805 back to the main DC input from the bridge rectifier. It's 100% better now.

[@IanScottJohnston]

UPDATE: I have fixed the noisy bluetooth module with an isolated DC-DC (0505) converter after the 7805 regulator, and wiring the supply to the 7805 back to the main DC input from the bridge rectifier. I also left the BT module 0Vdc connection tied to the GND pin of the pre-amp IC. The ground loop is gone and it's sounding 100% better now. Very, very little background noise. I've also had to fit a small heatsink to the 7805 now as the incoming DC is higher and there's more load on it with the DC-DC converter. All good. www.ianjohnston.com/images/stories/IanJ/SharpGF6060/BT.jpg

[@mattsan70]

You need an isolated supply for the BT module. You've basically got a ground loop. Get a decoupler.

[@IanScottJohnston]

I'll give that a bash this weekend.

[@simontay4851]

@@IanScottJohnston put a small high mH value inductor in series with the BT module supply to filter the high frequency noise and take the supply for the BT module directly from the bridge rectifier before the ripple filter transistor so any noise is not coupled to the audio preamp circuit. Maybe even make your own copy of the ripple filter.

[@Peter12662]

I had a different BT module but I used one of these www.digikey.com/product-detail/en/recom-power/RFM-0505S/945-3159-ND/8550767

[@IanScottJohnston]

@@simontay4851 I originally had the supply across the main bulk cap on the rectifier output....it was noisier albeit without an extra inductor.....nice idea of the copy ripple filter though. I will play with some ideas this wekend though and possibly a wee follow up video. For now the quietest solution is as I have it in the video.

[@muckabeaga2536]

As @morenormal said, you need an isolated supply for your BT board. Check out M Caldeira's series of videos about this very topic (kzbin.info/www/bejne/hKrYeJWPbaZnmJo). He uses a variety of methods, but his most recent one is to use a suitable dc-dc converter. Problem solved!;-)

[@jp040759]

Timely video. I just refurbed my 1978 Radio Shack ghetto blaster I got specifically to take to College. I got tired of all the scratchy controls. Now it sounds like new. I will definitely look into the bluetooth modules. I got one 6 years ago to have my PC Bluetoothed to my home stereo system receiver. I just wonder what the frequency response the Bluetooth gizmos are designed to reproduce. It is so funny to see how large the 7805 is next to the Bluetooth module.

[@DaveMcAnulty]

Be neat to use that "Mute" output to drive a relay to do the Radio/Bluetooth switching.

[@robbieaussievic]

.... Good thinking, although, BT auto pair with phone in your pocket, and you would have to manually select mute on app to switch to radio. ( ? )

[@user-mp7vn7te4h]

Спасибо тебе большое

[@kittsdiy]

i have used many of those chinese BT boards .. they work fine if they are not on the same PSU of the amplifier .. seems the audio GND and VCC can"t be the same .. 1:1 audio transformer in the audio pad or isolated DC-DC and noise is gone ...

[@SeanBZA]

I think they have high pulse currents in the power supply, from running the bluetooth keep alive transmissions, so you will get noise. Definitely looks like you need to have an isolated supply for them, to keep that pulse current out of the audio path.

[@SatyajitRoy2048]

I think changing the GND connection of BT module at another point might solve the noise problem. Looks like its infected noise.

[@electronicshobbyistmushtha5448]

can you make a video on your lab?????

[@robbieaussievic]

..... I don't care what INTERPOL say, I think your a 'Top Bloke'. I was thinking extending the BT LED up to the indicator panel.

[@IanScottJohnston]

I did think about that.....but the bluetooth pairing seems so faultless and quick n easy I didn't bother. Hmmmm!

[@Rich-on6fe]

I attempted something similar recently to find that the Bluetooth device was indeed only as good as its price had suggested it should be. It would arguably have been usable if I'd been desperate for it but under the circumstances I decided it was crap and threw it in the bin. Noisy, buzzy, refused to work unless it was charging and charging created noise. When it was not connected, even noisier. Wasted an evening on the bloody thing.

[@Keep-Exploring128]

At the 2:66 i almost ended up on the floor :)

[@ahmadazam2843]

halo mister radio me not pungsi fm 🙏🙏🙏helep me mister🙏🙏🙏🙏🙏🙏🙏