I built the Velleman MK194 kit. The radio works well, but there are several questions:
1.) Where can I get a circuit diagram of the radio?
2.) Can I attach a RDS-module to it in order to determine the received station? Where can I get a RDS-module?
3.) The module is designed for operating with 9 volts. However when using a battery as power source, its voltage will go down. Which is the minimum voltage required for operation? Which is the maximum voltage with which one can operates the device?
What about RDS-modules or frequency counters from other manufacturers?
Sorry, we are not aware of those and we do not have any experience with them.
Which is the manufacturer of the used FM-module KST-MW004? Can one buy it separately? Has someone a circuit diagram of the module?
Can the microcontroller PIC16F630-I/P be bought separately? Or must one always program it by its own means?
As the FM-modul KST-MW004 offers Stereo, it would be great that there would be a notice in the assembly instruction how to upgrade it to stereo.
The module is manufactured by Manlex.
Sorry, we do not sell it as a separate part.
Please Google for the datasheet.
Also the programmed controller is not available separately.
Sorry, since this is not an open source project, we cannot supply the code or hex files.
Basically, the best way to get hold of a spare controller and tuner module is to buy a second kit.
[quote=“Obelixx”]
As the FM-modul KST-MW004 offers Stereo, it would be great that there would be a notice in the assembly instruction how to upgrade it to stereo.[/quote]
Seems to me, if you copy the circuit of the left channel and connect it to the right channel out of the module you get stereo.
See pin 8 of FM module marked L-out on the diagram. Connect your copied circuit to Pin 7 marked R-out.
Don’t know if you have to tell the FM module to switch to stereo, as this would require to reprogram the PIC.
About the min and max voltage see datasheet of LM386, this seems to be the critical part since all other parts run of the stabilized 5V, the LM386 runs of stabilized input that means in case of 9V battery minus Diode voltage drop a voltage of about 8.4V.
Depending on the Model LM386(N) it’s capable of running on a range from about 5V through 12V. Note that if running from 12V the ua78L05 will get hot as it has to dissipate the 7V difference between 12V supply and the wanted 5V output.
If you decide to run on minimum(e.g. 5V) you must omit ua78L05 and you could run it from for instance USB.
On a side note: wanted to buy one of these kits myself; seems better to buy two… and experiment a bit.
Hope this helps.
Greetz Deekay
[quote=“Deekay”][quote=“Obelixx”]
As the FM-modul KST-MW004 offers Stereo, it would be great that there would be a notice in the assembly instruction how to upgrade it to stereo.[/quote]
Seems to me, if you copy the circuit of the left channel and connect it to the right channel out of the module you get stereo.
See pin 8 of FM module marked L-out on the diagram. Connect your copied circuit to Pin 7 marked R-out.
Don’t know if you have to tell the FM module to switch to stereo, as this would require to reprogram the PIC.[/quote]
IMHO the Ultimate Stereo Solution would be to buy 2 sets and the only difference would be the Pins 7 & 8 … see above
Maybe I oversee something? (With 2 times 4 presets, it could be done… But it isn’t an elegant solution, I agree.)
Cheers for an answer!
I’ll order 2 MK194’s today…
In the firmware, the unit is set to ‘MONO’, to ensure good reception at all times (STEREO needs a higher signal strenght and has worse S/N ratio), so I’m afraid getting two kit will not help to get stereo.
Thank you for the answer… Indeed it sounded to good to be true… 
eh I mean the idea, not the MK194!
In the meanwhile I expanded the radio with a power supply, a VU-meter, and now building a logaritmic “S-Meter” based on a CA3189 (by origin a FM detector) and for the near future a active antenna…
For me this is[color=#4040BF] ultimate “hobby”[/color]
Cheers!
Pictures please!
When ever this project comes to it’s final accomplishment, and I promise it will, pictures will follow. But first dealing with some construction problems…
Cheers
Hi, i want to know wich frequencys the presets are located on.
In my region i don’t get any stations on them.
is it possible to change the Presets?
greetings,
haweyn