Optimized PSU-what type of caps?

[tel3]

I'm going to build the optimized PSU circuit for my Quad-SID and I am unsure of what type of 100nf and 330nf caps to get? (Mylar/Polystyrene, Ceramic, etc.) Does it even matter?

Thanks!

-tel3

[Wilba]

I've used Monolithic/Multilayer Ceramic capacitors for all the power supply and "bypass" capacitors... i.e. all those used in PSU or between +5v/ground of ICs. I'm no expert but they seem to work fine for me.

[stryd_one]

Actually I noticed last week that there is a bit of a shortcoming in documentation for newbies... All of the parts lists mention the cap and resistor values, but not types/tolerances. I was able to figure out what was required but I've been hanging around here for years. I wouldn't wanna be new to all this!

Might be worth noting for you uber clever hardware developer types :)

[Therezin]

This is another thing that's been getting to me too - I might have been hanging around here for ages, but I'm still at the planning stages of my SID. I bought all the bits for the optimised PSU, but the shop I got the bits only had 100nF in ceramic and 330 in mylar. Would there be any problem using them like this?

[Mr modnaR]

RS do a 330nF in ceramic, but they're £1.06 each and you have to buy ten of them!  :o anyone in the UK know of a better place?

[Altitude]

for most things, it should not matter unless the cap is needs to be precise. For bypass and power filter caps, it wont make any difference other than the physical size of the part.  here is some good reading:

http://musicsynthesizer.com/txt/caps2.txt

[stryd_one]

'course if money is a concern then polystyrene might be a bad call ;)

www.rsaustralia.com is where I got mine from for AUD$0.65c, which is less than 50c USD.

[Therezin]

That's cool. The other thing that's been bugging me (apologies for the thread hijack tel3) is the 14VDC output to the SID module. Is it really only 1 pin? That strikes me as a little odd...

[Mr modnaR]

you have to remember that the ground on the sid module goes all around the chip. the connection J2 on the sid module has +5VDC and a GND pin. it is there that the chip gets it's ground.

hope this helps.

ps i had trouble understanding this too at first, but i'm getting there thanks to the kind souls on this forum.  8)

[tel3]

Thanks everyone for the info. I realized after I made the post that I can probably use the same types as specified in the parts lists for the modules using the same values, being that they will be used in very much the same manner...Right??

Also, do the bypass caps go in place of the voltage regs, or in addition to them?

(apologies for the thread hijack tel3)

No prob, your questions will help me as well!

-tel3

[Therezin]

you have to remember that the ground on the sid module goes all around the chip. the connection J2 on the sid module has +5VDC and a GND pin. it is there that the chip gets it's ground.

hope this helps.

ps i had trouble understanding this too at first, but i'm getting there thanks to the kind souls on this forum.  8)

Thanks man, I appreciate the quick answer. Time to get soldering methinks..

[Mr modnaR]

Also, do the bypass caps go in place of the voltage regs, or in addition to them?

in addition.

[tel3]

Alright, Just so I am totally clear on this...

Where the Optimized PSU.pdf talks about not stuffing the voltage regs and shorting across the input and output line(number 3) of the where the v reg goes and it says "1000uf is ok", that is where I put the 1000uf caps in place of the voltage regs(across the in and out lines) right?? To me it looks as if you would just put jumper wire there? ???

-tel3

[Altitude]

No. that is referring to C5 (the big one) since there is some filtering already done on the PSU board, you do not need such a big cap

[tel3]

So, I do just put a jumper wire across the in and out lines?

Also, What exactly are these "bypass caps" and where do they go??

Should I change C5 from a 2200uF cap to a 1000uf cap?

-tel3

[Altitude]

you dont need to. If you already have the cap, then just use that and yes jumper the spot where the regulator was

What exactly are these "bypass caps" and where do they go??

Bypass caps go on the solder side between the pins of the IC's 5v input and ground.

look here:

http://www.midibox.org/forum/index.php?topic=4455.0

[tel3]

Bypass caps go on the solder side between the pins of the IC's 5v input and ground.

OK, I get it...

I am using the latest SmashTV boards. Does anyone know if they already have the bypass caps in the design?

-tel3

[Altitude]

yes they do

[tel3]

yes they do

I checked the info on SmashTV's page and got an answer.  :-[

Yeah, I always seem to find an answer soon after I post my questions for some reason? I guess I should try a little harder to find the answer before I make a post... ;)

-tel3

[tel3]

Is it absolutly necessary to remove/not stuff the 7805's in the Core? Or, can they be left in? (referring to them in the optimized PSU context)

It would be more convenient to have 'em in there in case I temporarily need a Core board for another project!  ;)

-tel3

[tel3]

Is it absolutly necessary to remove/not stuff the 7805's in the Core? Or, can they be left in? (referring to them in the optimized PSU context)

Well, anyone??

[Altitude]

they should be removed and bridged, the 5V coming from the optimized psu is already 5v

[tel3]

O.K. So, I've collected all the parts for the optimized PSU circuit and have figured out the placement of components on the board I'll be using! Yay!  ;D I'm getting excited!!! Tonight I will assemble my PSU board and I'll report back when I have it completed.  ;)

-tel3