EA TREM - switching caps to adjust speed range

[aaronkessman]

anyone done this successfully? What cap value did you use and what frequency range did you achieve?

I'd like to speed mine up a bit, is there any single cap that I could make switchable (instead of all 3 of those 0.1uF's) so that I could have one slow speed range, one medium, and one high?

[dubs]

try replacing 1uf caps with 0.068uf for more speed. Checkout Runoffgrooves site, there are mods there.

[smoguzbenjamin]

One resistor to ground in the oscillator network, can't remember which one, can be adjusted for a difference in speed.... Try tinkering with that

[u1061810]

It's the 2k2 resistor just before the speed (rate) control.Smaller resistor, faster speed. I think 1k works well.

[Torchy]

Well pleased with my EA trem (the ROG version).

Slightly OT - on the Tremulus Lune, they switch a cap in/out for a separate "rate double" switch. Could the same idea be applied to the AE Trem  :?:  

I thought of a resistor same value as the pot wired across lugs 1 & 3 (parallel ?) via a switch.  :?

[aaronkessman]

the mod on runoffgroove includes changing the value of the speed pot as well as the 2k2 resistor. would simply bridging the pot with a switchable resistor do? I'm sure it would to an extent, but has anyone messed around with that is what Im asking

[maximee]

Funny, I just finished my EA Trem (General Guitar Gadgets) the day before yesterday and I was asking myself the same questions...this was my second pedal, it works just great, I love it very much already

From what I understand (which is not a lot in electronics... ) the 2k2 (1k in the ROG schem) in front of the Rate pot represents the max. speed rate...e.g. the smaller this resistor is, the faster the trem can oscillate...so I'd suggest you max your speed pot and then play around with that resistor. I ended up using a 1.2k...

The maximum resistance of the pot itself represents the minimum oscillation rate...that means, the more ohms, the slower it is gonna be when the pot is fully turned  counter-clockwise...

Please correct me if I am wrong here
I don't wanna confuse anybody with my newbie theories...


I also found the original 1M Depth pot way too big...I think I'll go for a 500k or even 250k...
I didn't have a 25k volume pot, I used a 10k and it feels just fine...

Another easy mod is the pulsating LED and it is way cool...
check ROG for how to apply it...

[maximee]

another mod i am planning to do myself:

i want to be able to activate my tremolo wit ha momentary nonlatching stompswitch so that i am able to play throgh chord progressions and only have certain short chords "tremolo"ed...

what are good sturdy momentary switches to get?

[puretube]

in the new sensor parts catalog 2005
(maybe Aron will carry them soon, or maybe smallbear ?)

[maximee]

the new 2005 sensor parts catalogue... how could i forget about that

man, you make us REALLY wanna know what's in there  :?:

[strungout]

Oy.

The EA trem LFO was used in the Phozer (check runoffgroove.com). I had increased the cap trio values (same for all three) to get a slower sweep, so lowering them should speed up the LFO quite alot.

Ciao.

[nirvanas silence]

I found the simple LFO very limiting, a simple 555 circuit would yield much more options.  Maybe you could consider going that route?

[gez]

a simple 555 circuit would yield much more options

Except sine wave, which is why people like this thing (vintage/Fender vibe to it).

[R.G.]

Phase shift oscillators rely on the summation of phase shifts in three (or more) RC filters to cause 180 degree phase shift from the output of the active stage back to the input. Each section can contribute more than zero and less than 90 degrees of phase shift, and they work best when they're all roughly equal. When they're not equal, you need more stages or more gain to make the thing work. Because each RC section causes some losses, there must be a gain from the active device to balance the losses  in the phase shift network to get a loop gain of one or over to sustain oscillation.

Unbalanced PSO's like the EA trem change one of the RCs by changing one of the resistors of the three. This gives you a limited range of frequencies. If you change one of the RCs too much, or even two of them, you need different gain to get the thing to oscillate, so the observed effect is if you get the RCs too unbalanced, oscillation quits, or just won't change much no matter what you do to the RC constant you're changing.

You can get a wider range by changing two of the resistors at a time by using a dual pot. You can also do this with dual LDRs, etc.

You can switch all three capacitors at a time by using a chip like the CD4053 to flip between two cap values, or to parallel in another cap.

[Manolo Dudes]

another mod i am planning to do myself:

i want to be able to activate my tremolo wit ha momentary nonlatching stompswitch so that i am able to play throgh chord progressions and only have certain short chords "tremolo"ed...

what are good sturdy momentary switches to get?

That's exactly what I did. Look here.

[maximee]

Thanks Manolo Dudes.
I should be able to figure it out, although I don't speak Spanish...

I also want to do the Vibra-Matic Add-On...I found it on geofex and Piso-Tones. Unfortunately the soundclip is a dead link...

Anyone know any further sites with info/sounds on that one?
The search function didn't help...

[R.G.]

The Vibra Magic add-on causes the LFO oscillator to start up with each new note. At the start of a note, there is no tremolo. As you hold the note longer, the tremolo gradually builds up to a max as though it were continually on. I designed it based on an old Thomas Organ circuit.

[Manolo Dudes]

...Unfortunately the soundclip is a dead link...

Sorry!  :oops:  Try this:

http://www.pisotones.com/EA-Tremolo/MBC/Vibmatic/BM_TL_EA_VB.mp3

Due to various reasons I cannot edit pisotones.com at this moment... as soon as I can, I'll correct the link.

[maximee]

thanks...

i'm gonna build it for sure! this is going to be my ÃœBER-tremolo...  :wink:

[Roberto]

LFO from 2Hz to 8Hz with this schematic:
( Q4 Hfe>700) .

http://www.thundertomate.com/tremolo/G-tremolo.jpg