Mr modnaR

now that looks good, shame we can't see the blue front panel.

cheers, yeah that helps clear things up a lot, thank you. now to find a three or four output transformer!

see, now i don't get why that would work, and using the 6 and 12 from my existing transformer would not work?? is it because the two secondaries are joined? if so, could i get a 4 output transformer with 4 6VAC secondaries, and bridge two of them to make 12, and have two 6VACs? or is it the fact that the primary is common that is causing the problem? cheers.

no, i need smooth power unfortunately, grrr, seems like this plan didn't work. thank you for your patience and understanding. *returns to drawing board to weep slightly*

what i want however, is to get BOTH 6VAC and 12VAC from the transformer, with the idea of giving the 6VAC (rectified obviously) to the 7805 in order to save it from chewing up the extra volts when given the full transformer output. doing the whole 12VAC to 5VDC and 12VDC was what i tried initially, and the 7805 got hot too hot for my liking (don't worry i had it heatsinked!).

thanks for your suggestion. would something like this work?:

yes i think you're right, maybe i should chuck a 7812 in there, and bridge the regulators on the sid boards? what do you reckon on using the first transformer pin as ground then using a rectifier to give 12VAC and 6VAC above that? does that work?

in NorthernLightX's psu: the centre pin of his dual 12V transformer is used as ground. is this what i need to do with the first pin of s1 to give me 12VAC and 6VAC? i need enough to power 4xCores and 4xSIDs and 1xLED Backlight and Control Surface C! in recent tests, Altitude measure this lot pulling around 500mA, i would like around 1000mA if possible. thank you for your help.

thanks for explaining that! your reasoning stands, i just measured just under 5V between the two grounds. :'( now what? can i not do it this way with this transformer?

ok, i'm completely new to all this eletronical malarkey, so please treat me as a newbie, because that's what i am! why would the grounds HAVE to be connected? and why, if they were to be connected, would that bring bad things? i appreciate the input, thank you.

i see, no i'm keeping them separate, or is that not a good idea?

link the ground? it's AC, there is no ground, correct? or do you mean the centre two output pins on the transformer? still confused...

here's the link to the website it's available from, but there's no specsheet, i suppose you could email them: http://www.mini-itx.com/store/?c=10#picoPSU

i'm sorry, i don't understand what you mean by 'half the bridge is parallelised' ??? i read 12VAC across the two outer pins on the trafo, and 6VAC from the the middle to either outer pin. that was my logic: to get 6VAC and 12VAC from one trafo, so that the 7805 wouldn't have to do as much work. is there a way to do it with that trafo?

i'm pretty sure it's standard ATX, which looks like this:

well tk reckoned that some people had success with switching PSUs, but you need more bits on top of the PSU (for noise suppression) than if you just built a linear PSU. honestly, it's not that hard to do it yourself.

when i said ATX PSUs introduce high frequency noise into the SID, i meant through the power lines, not through the air.

well, yeah, the big ones are, i thought you were talking about the little one i posted the picture of.

well, no. technically it's a DC-DC converter, you need to input 12V. as for shielding, just stick it in a metal, earthed cage.

normal PC PSUs are a bit bulky for my liking, but you can get 120W PSUs the size of the ATX plug:

i was just using the picture as an example of a knob, not suggesting anyone should use them for encoders. i also dislike the white lines on encoder knobs. it's a shame i couldn't get hold of any i liked.

the MBFM circuits themselves only take what current they need. the 6.5A quoted is a maximum threshold that the PSU can provide. as long as what you are powering requires less, there should be no problem. it was suggested to me by TK, that PC PSUs were not suitable for my MBSID project, because they are switching power supplies, which means they'd introduce lots of high frequency noise into the SID. as to whether this applies to the FM, i don't know, but it might be worth looking into more before commiting yourself. hope this helps.

yeah i was about to say that! i think you'll find that most pressure cookers won't take vacuum. you need a short piece of 8-inch gas piping or something similar. plate the ends over with something thick, bolt down and seal one end, then put thin neoprene seal on other end to enable it to be opened easily, and voila!

thanks for the tip about the extra caps. this design seems to work well. fitted all the bits onto stripboard. took up 11tracks x 21 holes: quite compact! getting a stable 15V and 5V, though i've yet to try it on the 4 cores and SIDs. will keep you posted. @Altitude, can you not get hold of a 4 output 24V transformer, each with 6V? that way you could bridge a few, and make 12V, 5V and -12V quite easily. feeding the 7805 with ~7V (that's around 7V not 7VAC!) makes it run cool, which is a load off my mind! cheers for all the input!

glad to know you got it sorted! cheers for listening to the tracks, just some oldies really.