i’m very proud having my first DIY Synth just started! I decided to build a SID Synth with as much SID’s as possible and also a YMF262 FM Synth. When i tried to desolder the yac chips i was overtly too rough and broke some pins. But fortunatelly i had found another soundcard on ebay, bought it and now the YMF scheme is ready soldered.
I thought about doing the same 19" version as shown on the ucapps site, but i came to the conclusion, that my 19" Cabinet is already full enough and a desktop version would also be very beautiful. So i just drafted an idea i had last night. I want to build the FM Synth in a white coloured frontpanel and some wooden parts on the side…
here is a small draft of my idea… these days i’ll take my order from the tax office and build the rest of the schmes which were needed
ps: sry for bad english skills
ppps: the draft is build with the original version jpgs of TK and just arranged in another way
all modules are ready soldered, dinx doutx, core and ymf module are done. Today i wanted to buy an transformer, but i read in the forum that it is possible to use the c64 one. i have one laing around and so i decided to use this. can anyvbody tell me if i need some accomodations or can i use it directly? has somebody maybe a scheme about the c64 transformer pinning?
I believe that someone has been working on a schematic for using the MBSID Optimised PSU with the MBFM but it might be a little while before they can talk about it… But it has been described before. You do need to add some circuitry to make it work.
@foona: hey thank you very much! i love to hearing that …
i already downloaded the scheffer software to but i did not jet found an option to make white panels there, just black ones. but at the website they also offer white one … i’ll phone them tomrrow and ask if that would be possible
@strydeone:
yesterday night i watched the psu options which were provided at the wiki and i’m not sure if i shall take one of these, the c64 one, a already build ±12v one … or however. Do you know if they all work fine or if there are some problems with the fm and one of these psu systems?
i thought about method 3 “3. Then there are two excamples of how to connect two identical 12v power adaptors. It is very important to use two identical ones! Same brand, same rating, best bought in the same shop the same day! You get these in regulated and unregulated versions.”
Well, the C64 optimised psu is not bipolar so it requires some modification… Using two EXACT same PSU’s should work, and has for some people, but it’s also caused trouble for others. Just my own personal opinion, I would not go that way.
If I was you right now, I would be waiting for that person (who shall remain nameless until they announce this themselves) to return with a known and working solution, or I would look at NorthernLightX 's very big informative PSU thread… You linked to a +/-12V transformer, personally I’d go for the +/-15V and use circuit #1 from the wiki page - which in case anyone’s wondering, is this one: http://www.midibox.org/dokuwiki/bipolar_12v_psu. Quite a few of us have recently bought transformers from pollin.de: cheap transformer for bipolar PSUs at pollin.de Which look perfect for a power supply that would be bang-on for an FM, and various other projects too
thanks for your fast reply! yes i think it heps a lot and i’ll try to buid the same one if you think that works fine for the fm. another question, what is exactly meant with the double size of caps? aren’t they just 100n and 10u ones?
the ground conections in the middle are also connected aren’t they? i already ave the 78xx and 79xx here, i can’t build them in the circuit on the wrond direction? and one last thing … is the thing on the left side a diode and which one shall i use?
i’m sry but i’m not really experienced in electronical circuit but nevertheless i want to build it save and working fine. cnan i also use the mk528 with circuit scheme one … in the wiki they tell something about 15±v and this one is 13,6v is there any mdification needed with the 4,2v output or can i use that directly?
thanks for your fast reply! yes i think it heps a lot and i’ll try to buid the same one if you think that works fine for the fm. another question, what is exactly meant with the double size of caps? aren’t they just 100n and 10u ones?
the ground conections in the middle are also connected aren’t they? i already ave the 78xx and 79xx here, i can’t build them in the circuit on the wrond direction? and one last thing … is the thing on the left side a diode and which one shall i use?
i’m sry but i’m not really experienced in electronical circuit but nevertheless i want to build it save and working fine. cnan i also use the mk528 with circuit scheme one … in the wiki they tell something about 15±v and this one is 13,6v is there any mdification needed with the 4,2v output or can i use that directly?
thanks for your patience
markus
I wouldn’t worry about patience here.
If this forum has an abudance of anything, it’s patience…and information. ;D
When i started in the DIY electronics buissness, i hardly knew anything myself.
But by the help of google, forums like this one and patience iv’e learned alot.
thanks for your reply! i also read a few things and the 78xx and 79xx pinning should be clear now, thanks again! i found a cheap tranformer at reichelt and bought this, it’s just a single one, but as i understood the threats i read it shoukld also work fine with scheme 2 …
i bought
WIPPE 1832.3312 Wippschalter, 2-polig AUS, 20(4)A/250 1 1,95 Euro
FLINK 0,63A Feinsicherung 5x20mm, flink 0,63A 4 1,16 Euro
SB 140 SCHOTTKY-DIODE 1A/40V 4 0,53 Euro
FLINK 0,5A Feinsicherung 5x20mm, flink 0,5A 2 0,58 Euro
TEKO 364 ABS-Kunststoffgehäuse 311x170x87mm 1 15,50 Euro
MKS-2-5 100N WIMA Folienkondensator, Rm 5mm, 100nF 6 0,74 Euro
RAD 10/35 Elektrolytkondensator, 5x11mm, RM 2,0 10 0,41 Euro
EI 48/16,8 115 Trafo 10VA, 15V, 666mA 1 4,10 Euro
LEITPASTE 10GR Wärmeleitpaste, Metalloxydpulver, 10g 1 1,70 Euro
BSN 4.700/40 Snap-in Becher-Elko, 25x40mm, 4.700F/ 2 5,40 Euro
PL 112000 Sicherungshalter, 5x20mm, max. 6,3A-2 4 0,49 Euro
SM 10/16RAD Subminiatur-Elko, radial, 10µF/16Volt 4 0,29 Euro
V CK960/20 Aufsteckkühlkörper für Gehäuse TO-220 2 3,40 Euro
KES 1 Kaltgeräte-Einbaustecker, waagerecht 1 0,30 Euro
EI 42/14,8 109 Trafo 5VA, 9V, 556mA 1 3,30 Euro
FLINK 0,8A Feinsicherung 5x20mm, flink 0,8A 2 0,58 Euro
i hope the 15v 666mA and 9v 556ma transformer is enough for this project. i already thought about the fuses, they are obviously too little for using. For scheme 2 it is told that the double caps size of the elkos should be used, i took 4.700F/40v hope thats ok, and i hope the diodes will also work
i haven’t found a good and safety looking ± transformer, that’s why i decided to try it with this
Thanks Foona! I’ve had this reply on my to-do list, and now I get to take a break, thankyou
I’ll give some quick answers and extra info… Pardon me for being brief, but my browser has crashed 3 times while typing this reply… after the third time, I feel somewhat less poetic
what is exactly meant with the double size of caps? aren’t they just 100n and 10u ones?
That refers to the caps labelled C, or in that diagram, 2xC. See section 4 in that document for the size of those caps, which should be doubled if you use the design you refer to.
the ground conections in the middle are also connected aren’t they?
Yes (see foona’s post)
i already ave the 78xx and 79xx here, i can’t build them in the circuit on the wrond direction?
You can, and it won’t work and may blow things up. Not highly recommended Make sure you get the correct datasheet (see foona’s post)
is the thing on the left side a diode and which one shall i use?
well on the seft is the transformer… Diagram one shows a rectifier after that, which is a box with an arrow onit - that’s your four diodes. The other symbols which look like an arrow pointing at a wall are diodes. Essentially, they make the electricity only flow in one direction (electrons, ie negative charge, go in the direction of the arrow). This takes the AC current and makes it DC.
cnan i also use the mk528 with circuit scheme one …
Yes it’s recommended. I will
in the wiki they tell something about 15±v and this one is 13,6v is there any mdification needed
Well, no, is the short answer… Long answer goes somewhere though…
in the wiki page it says:
The regulators need a voltage 3v higher than their output to work correctly.
That’s kinda right. The voltage regulators need an input which is 2V greater than their output**. This is because the electronics in there need power. Also, the diodes tend to cause a bit of ‘friction’ (all those electrons smacking that wall) and that means that they drop about 1V also. So, in total, you should aim for around 3V greater input, than output.
So, to get 12V out after the rectifiers and regulators, you really want 15V to be out put by the transformer.
Also take note of:
Many small printtransformers will give more than their rated voltage when little current is drawn.
The audio circuitry does not use a lot of power, mostly because there are no big flashy lights or heat or moving ports, which all eat lots of power. The quote from the wiki I pasted there is a hint, that perhaps your transformer may actually output a little more than what it is rated to. So ,maybe our 13.6V will actually output as much as 14V or so
** Coming back to the regulators - if your circuit does not draw too much current, then the regulator may need as little as 1.5V greater input than output. This, combined with the above, means we may only need about 14.5V input.
If you’ve done your math You already noticed that we are short by about 0.5V… So in theory, the pollin transformers should not work… However nILS put his $$ on the line and tested them, and sure enough he has assured us that they work a treat. Which just goes to show what theory is good for
with the 4,2v output or can i use that directly?
You won’t use that at all. Using the above theory, the +8V output of the transformer is meant for a regulated 5V circuit, and the 4.2V is meant for a 3.3V circuit. We don’t use any 3.3V componentry, so you can leave that one disconnected
it’s just a single one, but as i understood the threats i read it shoukld also work fine with scheme 2 …
I don’t know if anyone’s actually tried it yet, so please inform us of your progress
i hope the 15v 666mA and 9v 556ma transformer is enough for this project.
15V@666mA definitely, that’s lots.
9V@556mA…uhm… Maybe. I hope you don’t have lots of LEDs or a hungry backlight on your LCD.
For scheme 2 it is told that the double caps size of the elkos should be used, i took 4.700F/40v hope thats ok, and i hope the diodes will also work
Ahh I see you’ve been doing your reading, nice one. Next time, tell me that you found the answer to the question you asked me, so I don’t spend an hour typing something you already learned
i haven’t found a good and safety looking ± transformer, that’s why i decided to try it with this
thanks again for your reply … yes i did my homework and read a lot. please don’t worry about ordering some caps, and i don’t believe that your post was senseless, i read it very interested and talked tonight to an electrician, who told me that solution 1 would be the best. but i’ll try it with the single transformer and tell you if it works. but nevertheless i’m verry glad aboutyour answer and am very sorry about making you the work!
iv’e learned alot.