Capacitor question, sorry if this is in the wrong forum..

Frequently asked questions on capacitor types, ratings, brands, use and abuse.
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beej67
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Post by beej67 »

I'm new around here and I'm not certain I fully understand the post filing system you guys work within.

I'm a civil engineer, and we typically adhere to the Magic Smoke theory of electronics, so my background is very limited. Two classes in college, almost two decades ago. I'm just getting into this stuff by building some projects from tonepad.com. Successfully completed the rebote 2.5 delay, so I'd like to move next to the filter/sample/hold (Maestro FSH1) build, and I'm struggling with the parts list. On the capacitors, they list a "0.03" capacitor, but don't have units beside it. 0.03 Faraday is a big godfarging capacitor, and I don't think it's even available in a through hole termination format. The board diagram seems to indicate it's no bigger than a resistor, and the circuit diagram doesn't even list a polarity. Should this thing be 0.03 uF or pF?

reference:

http://www.tonepad.com/project.asp?id=50

Thanks for any help in advance.

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Post by Nocentelli »

0.03 microfarads, or more likely 33nF.
modman wrote: Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...

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Post by beej67 »

How do I tell for sure? Should I buy a spread of values and try different capacitors until one works? Will that screw anything up?

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Post by phatt »

beej67 wrote:How do I tell for sure? Should I buy a spread of values and try different capacitors until one works? Will that screw anything up?
Only way to know for sure is speak to the horses mouth,, Tonepad. :wink:

Meantime have a chat with the great goo-gull bird,,,might get you there faster.
http://www.electricaltechnology.org/201 ... c-non.html

And here; http://www.seymourduncan.com/forum/show ... tor-values

As already mentioned,,.03 will most likely be 33nF.
Yes it takes a while to get your head around cap values and the way in which they are labeled,, I had to get help when I started out but once you get the hang of it becomes easy to work out. Same with the colour bands on resistors,, :roll: takes a while but you Will get there with time. :blackeye
Cheers,, Phil.

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Post by grrrunge »

I've built a few of these. Fun project :)
There are several cap values on that schematic, that just say .001 or .03. It seems like common (though really really bad) practice to just assume that values are in µF if no denominator is given. In this case the values all land in the nF range, which is what you should get ;)

.15 = 150nF
.05 = 50 nF (47 nF is fine here)
.03 = 30nF (33 nF is fine here)
.001 = 1nF

For tonepad projects you're usually best off getting box caps with 5mm leg spacing and long leads. They'll fit in anywhere ;)
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Post by beej67 »

Thanks for all the help.

I emailed tonepad. If they don't get back to me I'll presume uF and punch out the Mouser order.

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Post by beej67 »

From the horse's mouth:
yes. all capacitor values that have the units missing are uF's. that'd be a 0.03uF, you're probably going to find 0.033uF which is fine.

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Post by DrNomis »

beej67 wrote:From the horse's mouth:
yes. all capacitor values that have the units missing are uF's. that'd be a 0.03uF, you're probably going to find 0.033uF which is fine.


The reason why it's not really good practice to quote those cap values in microfarads rather than in nanofarads is that the little decimal point (.) could become hard to distinguish due to printing errors, sometimes the decimal point is replaced with the letter "u", for example 4u7 instead of 4.7uF...... :thumbsup
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Post by Nocentelli »

It's definitely 0.03 microfarads, there is no doubt. You are unlikely to find a 0.03 microfarad cap though, almost every vendor WILL sell 33nF caps, which are 0.033 microfarads and close enough.
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Post by DrNomis »

Nocentelli wrote:It's definitely 0.03 microfarads, there is no doubt. You are unlikely to find a 0.03 microfarad cap though, almost every vendor WILL sell 33nF caps, which are 0.033 microfarads and close enough.

Considering that the tolerance can be anywhere between +/- 10%, I think it is perfectly okay to substitute a 33n cap for a 0.03uF cap, it should have no effect on the operation of a circuit unless the circuit is uber-critical..... :thumbsup
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Post by beej67 »

Mouser actually has 0.03uF in their stock list, but they're all expensive and special order so I went with the 0.033uF.

Thanks for the help and the discussion. My actual project is a little weird and probably ambitious for a beginner, but I wouldn't mind sharing it to get some opinions now that the thread is moving.

I play guitar, but I also do electronic music in the regime of ambient / noise as a hobby. Pursuant to that, I wanted to build something that I could easily manipulate from a bench to push weird sounds out of. I'm working completely with tonepad PCBs because I don't know enough electrical engineering to know what I'm doing with a custom job, and I figured I'd learn on the job. Part of my criteria is I wanted something small and manageable, with multiple effects in it, and the ability to swap them around in any order. I didn't need them in classic stomp box format. So here's the plan:

I already have the board built for a Rebote 2.5 delay, and I hotrodded one of the resistors to produce infinite delays and grungy feedback, per the instructions on the sheet. I have a 7inx11in enclosure, which I lined with urethane foam, and cut squares out of it to fit the board. I put a plate on top of acrylic plastic so you can see the guts of it below it, mounted my knobs in that, and had one input and output jack. Instead of wiring the input and output jacks straight to the board, I wired them to mini banana plug sockets, that I could connect to the board with jumpers. Image:

Image

Excuse my choice of wire colors. It's what I had laying around.

The plan is to put more tonepad boards in there, also wireable with banana plug jumpers, so I can rearrange them or even feedback them if I wanted. I've ordered a Ross Phaser, a Rebote 3 Delay, a Tremulus Lune tremelo, and a Maestro FSH1 filter/sample/hold board. That should pretty much fill the enclosure out. The ultimate goal of this contraption will be to feed a guitar signal into it, and then knob twiddle to make evolving ambient noise, somewhat akin to what those "modular synth" nerds do.

The rebote 2.5 seems to work, although it does occasionally cut out, so I need to go back and check some of the solder points. (rookie errors probably) Among the experienced crowd here, do you see any potential pitfalls with the plan?

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Post by DrNomis »

beej67 wrote:Mouser actually has 0.03uF in their stock list, but they're all expensive and special order so I went with the 0.033uF.

Thanks for the help and the discussion. My actual project is a little weird and probably ambitious for a beginner, but I wouldn't mind sharing it to get some opinions now that the thread is moving.

I play guitar, but I also do electronic music in the regime of ambient / noise as a hobby. Pursuant to that, I wanted to build something that I could easily manipulate from a bench to push weird sounds out of. I'm working completely with tonepad PCBs because I don't know enough electrical engineering to know what I'm doing with a custom job, and I figured I'd learn on the job. Part of my criteria is I wanted something small and manageable, with multiple effects in it, and the ability to swap them around in any order. I didn't need them in classic stomp box format. So here's the plan:

I already have the board built for a Rebote 2.5 delay, and I hotrodded one of the resistors to produce infinite delays and grungy feedback, per the instructions on the sheet. I have a 7inx11in enclosure, which I lined with urethane foam, and cut squares out of it to fit the board. I put a plate on top of acrylic plastic so you can see the guts of it below it, mounted my knobs in that, and had one input and output jack. Instead of wiring the input and output jacks straight to the board, I wired them to mini banana plug sockets, that I could connect to the board with jumpers. Image:

[ Image ]

Excuse my choice of wire colors. It's what I had laying around.

The plan is to put more tonepad boards in there, also wireable with banana plug jumpers, so I can rearrange them or even feedback them if I wanted. I've ordered a Ross Phaser, a Rebote 3 Delay, a Tremulus Lune tremelo, and a Maestro FSH1 filter/sample/hold board. That should pretty much fill the enclosure out. The ultimate goal of this contraption will be to feed a guitar signal into it, and then knob twiddle to make evolving ambient noise, somewhat akin to what those "modular synth" nerds do.

The rebote 2.5 seems to work, although it does occasionally cut out, so I need to go back and check some of the solder points. (rookie errors probably) Among the experienced crowd here, do you see any potential pitfalls with the plan?

Sounds pretty cool, I used to do something similar with an Ibanez Digital Delay pedal, it had two output sockets and I used to get it to feedback on itself by connecting one of the output sockets to the input with an instrument lead, it gave me some trippy Dub Delay effects.... :thumbsup
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Post by beej67 »

DrNomis wrote:Sounds pretty cool, I used to do something similar with an Ibanez Digital Delay pedal, it had two output sockets and I used to get it to feedback on itself by connecting one of the output sockets to the input with an instrument lead, it gave me some trippy Dub Delay effects.... :thumbsup
I should be able to do that with the one delay I already have, because it's jumpered with stackable banana plugs. One out can become as many outs as I need or want. That was my hope anyway.

I may need something to serve as a simple mixer though. Just to take a signal from a jumper, reduce the gain, and pass it on. You guys got any links to a simple project like that? Couldn't be too hard, I wouldn't think.

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Post by Nocentelli »

Maestro FSH is a great circuit. Took me a long while to actually get it going, but I wasn't using a tonepad board.

Single opamp mixer is probably enough for your purposes:

Image

...if you're just planning to mix the outputs from several parallel effects. If you want to mix in some direct, unbuffered guitar I'm not sure those "high impedance" 10k input mix pots are high enough, but you'd probably want to buffer the guitar input before splitting it to separate parallel effects modules anyway.
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