BTW some of the circuit was stolen from this: http://xkcd.com/730/
but shhh… don’t tell him, he may want royalties.
Hahaha, I had a good laugh while reading that schematic! Thanks! 
yo, cool background track! mbfm-powered? very nice!
yo, cool background track! mbfm-powered? very nice!
TK really brought ‘cool educational television theme song’ vibe on that track.
Will the schematics be posted online? I am trying to be a bit more diligent about testing as I go and really want to make sure I get continuity on the tracks for the SMD devices. Since some of them run under the chips, it would be easier if I could have a PDF I can zoom down into (much like the MB6582 one). If no, I can make due but thought I’d ask
Wiki updated:
Here is the PDF of the base PCB. Ground plane is removed. Pads with no tracks can be assumed connected to ground.
http://www.mb6582.org/sammichFM/sammichFM_Base_PCB_Rev_1.pdf
w00t thanks Wilba!
Well it took two late nights but my sammichFM now powers up and shows Ready! I’ll be trying to load the firmware today, though I haven’t been brave enough to supply power to the FM chips just yet.
Wilba, you did a fantastic job with the kit! It has all the wonderful details that made building it fun and even relaxing. The little things, like having the header pins snap-in (which meant I didn’t have to take the header down, tack it, then burn my finger while trying to adjust it so it’s vertical) and having snap-in sockets. Very cool, and the LCD looks sexah too!
WOW… Impressive..
Congratulation for this beautifull little box.
I’ll definitely have to order one… maybe next month.
I’m surprised to read in the feature list:
“4 simultaneous instruments of 6 voice polyphony each, plus drum kit. Each voice is a 4 operator waveform.”
That makes 24 voices of 4 operators + drum kit ??
That sounds much more than in the opl3 spec:
“6 four operators melody sounds + 3 two operators melody sonds + 5 rythm sound”.
Did i miss something ?
Thanks,
Xavier
No, you’re right… I’m paraphrasing TK’s MIDIbox FM specifications here: http://www.ucapps.de/midibox_fm.html
Maybe it should be written as “4 simultaneous instruments of up to 6 voice polyphony each, plus drum kit. Each voice is a 4 operator waveform.”
Or you can propose an alternative.
OK. thanks for the clarification
Maybe something like :
“6 four operator voices played by 4 simultaneous different instruments plus drum kit.”
Xavier
I think there is an error in the voltage testing picture (the one with the colored dots) for the base PCB. Pin 2 of IC9 (2nd from the top on the left row) is connected to GND and not +5V. I noticed that during the voltage/continuity testing phase and looked it up in the PCB layout PDF.
Regards
trilader
Are you using the 1.0 version of the build guide? I believe that issue has been fixed in that version?
I emailed the link to the v1.0 build guide but forgot to update the link in the wiki. Fixed now.
Also, until the build guide is updated again, I recommend MIDIbox FM v1.4c which fixes issues with short notes for drum sounds.
Crikey! I slack for a few months and come back and Wilba’s gone and designed a whole new project. Beautiful job as always!
Ok, no problem then. I was on my desktop and didn’t look at the version number.
Maybe a potential PSU candidate for the sammichFM?
Reichelt doesn’t carry suitable PSUs, at least I haven’t found one.
That looks like a switched PSU to me (though I’m having Google Translate fail). You’d want a linear regulated PSU as the best option typically. Switchmode will work, but can induce noise (and usually causes a big flame-war here on the forums about half the time it’s mentioned )
Also quite often, voltage-switchable psus like the one you mentioned do provide the maximum current (1A from specs) only at the lower voltage settings.
@m00dawg: Well, the description says “stabilisiert” i.e. “stabilized”, which to me indicates that it’s a transformer based psu. Do switch-mode PSUs need to be stabilized? Probably not. But I’m not sure about this. The product description is quite poor.
@Hawkeye: The sammichFM draws about 200mA according to the sammichFM building guide. If 1A is provided only in the lower voltage range, I guess at least 200mA should be provided at 9V. But still guessing…
@all: Any recommendations for a transformer based (linear) power supply here in Germany/Europe? :clover:
Don’t you guys have local fleamarkets? There are lots of those PSUs available round here…