449
Item nr.


Homebuilt Fantasy Stereo radio

Failed Stereo project.


Data for Homebuilt Fantasy
ProductionThe Netherlands, 2017.
BandsFM.
CabinetPlastic.
PowerAC 230V.
DocumentsPlan.

The Design

On internet I found a funny module: the 747D FM, USB, SD music player, operating from 5V DC and including remote control. The idea was to construct a remote controlled stereo set by building this unit in old speaker units, together with an amplifier from PC speakers.

Obtained1/2017 from Scrap parts.
Condition5.
DisposedScrapped 1/2017.

This Object

The first prototype of my new stereo set was constructed in a pair of PC speakers. I wanted to do some measurements and tests and then, in case of success, buy some bigger wood speakers to have the same idea but with better sound.

In the side of the master speaker I sawed an opening and mounted the 747D unit. I added an L7805 voltage stabilizer to supply 5V to the unit, from the buffer elco of the amplifier. My idead for the final unit was that it could be used in Mono mode (just the Master) or Stereo (with the slave also connected). This worked more or less OK, I immediately got sound from the speakers and I could use the remote control, and play radio and MP3 files as well. Problem was that the pulsed current drain from the FM/MP3 unit caused a heavy noise in the amplifier! That this was really power induced I could verify by turning the amplifier volume control to zero: a nasty humming beep sound could still be heard.

When I tried to fix this with some extra elco's and tested with an external power supply, the 747D suddenly went black and broke down completely. After this failure, the processor chip immediately runs very hot after applying power.

And this was the second unit dying on my workbench within a week! A few days earlier I had tried to built one into my Sloper set, and that one also broke down while I tried to fix some problems. My conclusion to date is that these units are not very robust. A follow up project must have better power supply, perhaps even completely separate from the analogue parts of the project.

After failure of this project, I reworked the remains into a little micro amplifier, which was subsequently used by my offspring with BNS E12 speakers (60W).

A few years later, I did some more projects with Bluetooth sets and then they were very successful.


Part of Gerard's Radio Corner.
Generated by SiteBuilder on 26/2/2024 by Gerard (g.tel@uu.nl)