EA Trem

[Axmanjr]

Cool, thanks Kaiowas!  I'll get to reading!

[Kaiowas]

Glad to help!

[Axmanjr]

I'm looking around, and I noticed that I can't seem to find a 25k audio pot anywhere!  What a bummer!  Are they still around?  If not, then what other substitute values can I use for the pots?

Also I'm having trouble finding the caps in both those schematics.  I can't find the right type (metal, film...).I can't find any caps in those values.  Instead, I found weird values- like 47Mf.

[Kaiowas]

Axmanjr,

I think the 25K audio pot is hard to find, very hard to find, in the article i told you earlier, you may read that you can change a linear pot to a log (audio) one, they tell you how to do it very clearly.

About the caps types, you can use any non-polarized type (ceramyc, film, etc) for the non-polarized caps in there (C8,C1,C2,C4,C5,C6,C7), and electrolytics for the other ones (C9,C3).

An about the caps values, i think the only value not-so-easy-to-find is the 0.05uF (C8), but anyway, if you don't find the right value of cap, you can put some caps in parallel to add them (i.e. to make the 0.05uF, you can put 2 of 0.022uF in parallel, C=C1+C2, C=0.022uF+0.022uF, C= 0.044uF, and 0.044uF is pretty close to 0.05uF).

You also can put them in series (C=(C1*C2)/(C1+C2)).

OH! i'm assuming you're using the "improved EA Tremolo" from JD.

Tell me if you don't understand something.

Bye!

[Axmanjr]

Thanks again Kaiowas!  I haven't read the part where the article explains about changing linear pots to audio pots- but I'm getting there !  

In this diagram http://www.generalguitargadgets.com/v2/diagrams/eatrem2_sc.gif, what does sw1a, sw1b, and sw1c mean.  I'm assuming that sw1 means the footswitch, but what are the 3 different numbers that are scattered throughout the schematic all about?

And also, since I'm still a beginner and don't want to trouble myself as much as I already am, is it possible to not include the DC Jack in the schem?  If so, how would I do this?  Would I simply just omit J3and have the (+) terminal of the battery connect to R15 and so on... and R18 would connect to it also?  Please let me know if this is right.

[smoguzbenjamin]

Sw1a, b, and c refer to the poles of a 3PDT switch. You're right on the exclusion off the DC jack though.

[Axmanjr]

Okay, here we go again!  After reading the previous article on POTs, I noticed that you can change an audio/log pot into a reverse audio pot by using a resistor.  However, there is nothing there about changing values of pots (say- like from a 50K to a 25K).  There also isn't anything on how to change pots from log to linear (or vice versa).  Is it possible to accomplish these things?

Also, as again, I CANNOT find the 25k audio pots anywhere!  I went to kiesubs (an electronics store here in Vegas- who boasts about having everything!) and I couldn't find them there.  So, is there any other possible pot values that I could use to replace the 25k logs (maybe 50k logs- or even 10k)?  How will this affect the effect pedal if I could do it?

I'm using this schematic http://www.generalguitargadgets.com/v2/diagrams/eatrem2_sc.gif.  Thanks for any help!

[Mike Burgundy]

I'd say RA means Reverse Audio, or reverse log.
Use a regular log pot wired in reverse, or a linear, or... experiment and see which you like.
GGG has the original EA, Runoffgroove has a modded version. which is the preferred version? Dunno. For runoffgroove, it's the modded one (duh) but your mileage may vary. Tinker, and come up with your own
Mucking about with values is right there at the heart of modding, which in itself is at the heart of improving *your* sound. You won't blow up anything by changing pot values or cap values, so knock yourself out. Keep a log of what you change, and what happens to the sound. Try to understand why...this is a very powerful learning experience, comparable in my mind to having lessons vs. playing in a band.
Enjoy.
*edit*: I forgot about a page 2. Sorry 'bout that
It's easy to make a linear pot into whatever you want, but more or less pointless to mod a log one. Just use the log, if it seems to concentrate all of it's sweep in one corner, buy a linear pot.
Stick in a 50k and a 10 k and see which one you like best. where are you? Mouser, Farnell, my shop around the corner all carry 25k? Smallbear, too.

[Axmanjr]

Thanks for the reply and motivation Mike!

I guess I should experiment.  I was under the assumption that if I used different values in a schematic that I might mess something up.  But since I'm breadboarding it first, then it should be no problem!  I'm from Las Vegas, NV.  I tried going about finding all of my components without the need of ordering, but I guess that may be needed- of course I'll still experiment with what I may have readily available here!

Okay, so I'll post back later (say a week) concering the progress of my pedal.  Thanks!

[Kaiowas]

Let us know if we can help you out when you get what you need!!

[Paul Marossy]

I used some 1uF films in mine. They are pretty small in physical size, too. Someone gave them to me a while ago, and I thought to myself "what the heck can I use these for?" Enter the EA tremolo...

[Axmanjr]

I sure will Kaiowas!

Hey Paul, where in Vegas are you from?  Where do you do all of your component shopping?

[smoguzbenjamin]

I built the runoffgroove one and I like it a lot. about the pot, you could use a tapering resistor to make a lin pot act like a reverse log pot

[Paul Marossy]

"Hey Paul, where in Vegas are you from? Where do you do all of your component shopping?"

I live in the NW part of town, near Summerlin. Lake Mead and US95 area.
Getting components is kind of a pain in the neck. I used to go to Sandy's Electronics a lot, and they and Kiesub Electronics have merged now. I haven't been there since that's happened. Sandy's has closed and moved their stuff into the Kiesub store off of Highland Drive.

I go to RadioShack a lot of the time for little stuff, but I try to avoid it these days since it is such a rip-off to get parts from them anymore.

For tube stuff, I use tubesandmore.com, thetubestore.com, hoffmanamps.com and partsexpress.com

I have placed a few orders with Mouser.com, too.

I have also scored a few things off of ebay, like Ge transistors, 2N5089s and 2N5457s.

It really all depends on what I need and how fast I want it. I haven't had to buy too much stuff outside of my parts stock for a while. Someone who used to be an instructor at DeAnza college at one time had given me bunches of resistors, caps, diodes, LEDs, enclosures, IC chips, transistors, solder type terminal strips, transformers and all kinds of other stuff. That has kept me going for just about a year now! (He used to own the coffee shop a few doors down from where I worked and we became good aquaintances since we both liked electronics)

[Axmanjr]

I'm up by Sunrise Mountain- next to the Nellis Base.  So a daily trip to Kiesubs is not particularly on my schedule!  I'm still a beginner... but I'm trying

[Chris S]

Hello EA temolo-ites

Is it possible to get the depth part of the curcuit so deep that the volume is actually going on and off. I am using the runoffgroove version and the first 25% has no effect (so it can be used as a volume boost too) I am happy to loose that part.

Thanks!

Chris

[smoguzbenjamin]

Uhmmm... Mmm lemme think... Maybe losing the resistors on one side of the depth pot, but it might start popping at you...

[Manolo Dudes]

Reduce significantly the value of the 180 Ohm resistor at the emmiter of the first transistor ant the depth will be increased. Not sure if it'll go where you want it to go  :roll:

[Manolo Dudes]

Reduce significantly the value of the 180 Ohm ...

Oooops!.. sorry. Now I see it shall increase the speed, not depth  :oops:

[smoguzbenjamin]

:mrgreen: That can be cool too you know. You could have a switch "Turbo" or something