OT: Who wants to build a 909?

[stevenclements]

I was sure I read in one of the notes you could swap in the Mylar/poly's for the 0.68's thanks for checking...

http://www.justradios.com/captips.html

http://www.justradios.com/uFnFpF.html

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

http://www.mikroelektronika.co.yu/engli ... keu/02.htm

http://www.kpsec.freeuk.com/components/capac.htm

I dunno 'bout y'all but I like pages like these... sounds to me like all caps should be Polystyrene Film if at all possible... but then I'm no EE

Has anyone ordered from here?

http://www.action-electronics.com/capacitr.htm

[stevenclements]

I got that mylar pack from china so I will have some 0.68s. Couldn't u use tantalum caps also? Mouser has 0.68s in Ta

I am almost tempted to get 1200 ($74) of those Nichons and just have a cartel on those bad boys, anyone game for a group buy?

ya know... I'm having a time finding some of the odd caps... but yeah I'd be in for group buy of these hard to find puppies... I wonder what the diff is with the tantalum ones? in one of those links I posted there was info on the cap construction materials and basic function or dysfunction because of the material. That's what affects the sound though... look at the guitar amp guys buying Mollary orange drops just cuz

[moogah]

I would stick with the film types, tants may not behave like we want.

[stevenclements]

I would stick with the film types, tants may not behave like we want.

Polystyrene Film: The Holy Grail of Film Capacitors, polystyrene has the most desirable electrical characteristics. With temperature coefficients as low as 30-40ppm (special) and typically less than 120ppm (standard), they have excellent linearity of temperature coefficient over the entire temperature range most equipment ever sees on this planet. Dielectric Absorption (.02%) is the lowest found in any capacitor variety. This makes the polystyrene cap the first choice for all critical timing circuits, such as VCO and VCF timings, and for all Sample / Hold circuits. Polystyrene caps cannot tolerate high temperatures (85 degrees Celsius max.), so they are not available in the metallized variety. Careless soldering can destroy them easily, and they are often poorly suited to automated production equipment. There is a persistent rumor that the only manufacturer in the world that made capacitor grade polystyrene film has ceased production. There is still stock in most values on the market, but people are well advised to save a few for top of the line circuits. There are some new polycarbonate caps which will approach the performance of
polystyrene.

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

Makes me wonder if I should be looking for more of these to keep on hand.

One other question... when in the 9090 bom it requests values of 50V... can larger values be replaced here? If so what sort of range is possible before the circuit is screwed up. As I understand it, the voltage rating indicates the maximum voltage which it is safe to use the capacitor.

I've read that it is common practice is to use capacitors well below their maximum operating voltage and temperature in order to ensure longevity.

So... if I find a good polystyene with the right capacitance value and rated for 630v or 400v wouldn't that be just ducky? Wouldn't it be a better cap to have in then one running at 50v?

Cheers

[stevenclements]

ok... here it is...

http://www.ecp.cc/cap-notes.html

One of the most common questions that shows up on DIY forums is what coupling caps to use in a particular application. <snip>

The voltage rating of a cap needs to be higher than any voltages that will be applied. In a solid state circuit, this is almost never a concern as most caps used for coupling are at least 200V, and usually higher (the exception to this is the use of electrolytics like Blackgates which is touched on a bit below.) In a tube circuit choosing a properly rated cap can be more important, but as long as the cap's voltage rating is higher than B+, you are usually okay. One thing to consider is that some high voltage capacitors are said to perform better at higher voltages. If used in low voltage circuits, theyare said to sounda bit flat. I don't know whether this is true or not. I was comfortable swapping caps in and out of a low voltage circuit without powering down, but not in a high voltage one.

[subatomic]

I got that mylar pack from china so I will have some 0.68s. Couldn't u use tantalum caps also? Mouser has 0.68s in Ta

I am almost tempted to get 1200 ($74) of those Nichons and just have a cartel on those bad boys, anyone game for a group buy?

sure, i'd buy, uh, 20 or so from you... 1200, that's kind of a lot...


there's also a 0.68uF "tantalum electrolytic" (not sure if it's polar or not)
http://www.newark.com/NewarkWebCommerce ... 0K8916&N=0

I think the mouser has "solid tantalum" 0.68uF (not sure if this is considered "electrolytic")
http://www.mouser.com/index.cfm?handler ... deid=74004

Does anyone know why it would matter (not work) to use non-polar in place of a polar cap?
It seems like non-polar should (theoretically) do everything a polar one could do, plus run backwards (being AC compatible)... I'd love to learn more about this...

For transformers, I found (at mouser)
120 to 16VAC 1.0A Wall Plug-In
33ct VAC / 1 Amp
30ct VAC / .5
I'm really hoping I'm reading this right, that it's 30V in serial, and 15 for each side (I take VCT to mean "center tapped", which I take to mean there's 0V in the center, and -15 on one side, +15 on the other?).

subatomic is getting a very nice excel spreadsheet together... with hyperlinks to mouser parts and hopefully we'll be able to find the others for relatively easy ordering... and with links - so others can find them easier.

(PS, the excel sheet is going well, PM me if you want a sneek peek, and I'll email it to you.
or if you'd like to help track down the last couple caps, and police my data to find places where I shouldn't have used ceramic, etc... please be my guest...).

[moogah]

In general I've found non-polar 'lytics to work fine as a replacement for polar 'lytics.

BTW: Those are some *excellent* capacitor resources you keep posting!

[stevenclements]

In general I've found non-polar 'lytics to work fine as a replacement for polar 'lytics.

BTW: Those are some *excellent* capacitor resources you keep posting!

Those links are just to good not to share. I'm all about spreading knowledge it does me no good otherwise. On that note. I just bought 10 units of the VERY hard to find IC CA3080 (thanks for the ebay note subatomic!)

They're on the way from China... I'll stick them in my stock and if anyone is having a hard time finding them let me know... As I mentioned to Subatomic recently. I sent the xls to a local guy who sells a lot of caps and resistors on ebay. He said he'll try to see how much of the list he can fill. If I get any of these hard to find one's I'm more then willing to share.


check this out...
http://www.newark.com/NewarkWebCommerce ... 474&QText=

Newark InOne Part No.: 30C8937

Manufacturer: VISHAY SPRAGUE

Manufacturer Part No.: 199D684X9035A1V1
Description: Tantalum Electrolytic Capacitor Capacitance:0.68uF; Capacitance Tolerance:+/- 10 %; Working Voltage, DC:35V; Package/Case:A; Terminal Type:Radial Leaded; Lead Pitch:0.100"; Mounting Type:Through Hole



cheers
Steve

[altitude]

They're on the way from China

I hope from a reliable source.. I saw those and I'm not convinced. Nikko had CA3080AE's (the mil spec ones) last time i ordered from them.

The vishays Ta .68 uf are the ones I am looking too

[stevenclements]

They're on the way from China

I hope from a reliable source.. I saw those and I'm not convinced. Nikko had CA3080AE's (the mil spec ones) last time i ordered from them.

The vishays Ta .68 uf are the ones I am looking too

I'll let you know... they're Harris Semiconductor 2MHz, operational transconductance amplifier (OTA). They appear operationaly similar to the intersil one...

http://www.datasheetarchive.com/datashe ... le=1098400

[moogah]

Didn't get them from HongKongSuperSeller, right? If so they are likely pulled from old boards. If you need 3080's or the harder to find 3280's I reccomend futurlec (google). They have LM394's cheap too. And a bunch of non-ROHS WIMA caps too..

I should really stop telling people about that place..

[subatomic]

I found everything IC/tranistor wise at mouser/digikey/nikko (mostly nikko)

If anyone finds a good source for a 4 mhz xtal, transformers, or the wierd cap values let me know PLEASE

Altitude, I looked at mouser, nikko (dalbani), and digikey for 2.7nF and for 0.0027uF neither came up...

Could you tell me where you found this one, or what search term you used?
Thanks...

note: to anyone interested... our .xls file with the part numbers is uploaded to introspectiv's file area, check it out and tell PM me if you have any changes you'd like to see... Some peer review of this doc would definately help 9090'ers source the correct parts! My goal is to make the barrier to entry on that project a lot lower... (if only mouser supported some kind of parts list file format a DIY project could submit to them... would make sourcing so much easier)...


UPDATE: I did find a 2.7nF at reichelt... seems overkill to spend overseas shipping on a single cap! still hoping to find something more local...

CY 22-5 2,7N Mica 2,7nF, 100V, ±1%, 6.5mm

[stevenclements]

Didn't get them from HongKongSuperSeller, right? If so they are likely pulled from old boards. If you need 3080's or the harder to find 3280's I reccomend futurlec (google). They have LM394's cheap too. And a bunch of non-ROHS WIMA caps too..

I should really stop telling people about that place..

ah BANNED! yeah that's the dork I ordered them from LOL... stoopid me.

well... it was only $30 we'll see what they look like when I get them... I'm on the futurlec site now

and there it is...

http://www.futurlec.com/Linear/CA3080Epr.shtml

[altitude]

Here are some more good links:

Power supplies/Tranformers (u are correct subatomic btw):

http://www.newton.dep.anl.gov/askasci/e ... g99316.htm

Capacitor value convertor (cause I always get confused):

http://www.onlineconversion.com/electri ... itance.htm

More capacitor stuff:

http://www.kpsec.freeuk.com/components/capac.htm

And another good 9090 DIY page:

http://members.lycos.nl/diy9090/frames.htm

[altitude]

Subatomic spoketh:

Altitude, I looked at mouser, nikko (dalbani), and digikey for 2.7nF and for 0.0027uF neither came up...

http://www.futurlec.com/CapPolyFilm.shtml for all your poly capacitor needs