# my first build - Tremolo



## ezcomes (Jul 28, 2008)

it turned out pretty not bad...i thought i did ok...i forgot to get a shot of the soldering, but i think i did surprisingly good!
haven't given it a proper test run, but it works...i like how the LED blinks to the rate of the tremolo setting...
i only had two issues...the first being...i should've soldered the DC power jack with it already installed...it melted a bit and i had a difficult time getting the nut back on...and the second was liftin the board into place with the pots just sitting there...took three attempts cuz they kept falling out...
all in all...not bad...learned some stuff...learned what not to do...learned some painting no-no's...but it worked the first time...and i can't wait for the next build!


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## keto (May 23, 2006)

Cool...that's how I started out (and according to Scott from axeandyoushallreceive, several other well known boutique pedal makers also). For me, it was addictive!

Is that the trem (I forget the name offhand) that has a volume control and can be set as a dedicated preamp/clean boost? I built one up on perf (name's gonna come to me any second here) and it's an awesome sounding trem. Oh ya, E A Trem. Is that what BYOC model theirs after?

Looks cool to me, sometimes mistakes in finishing can be happy accidents - has a nice roadworn look. Of course, sometimes mistakes are gruesome and require much elbow grease to remove and start over lol.


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## The Grin (May 5, 2009)

I want to do this one day. I want to make the weirdest sound I can.


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## Spikezone (Feb 2, 2006)

Cool! I love your graphic!
-Mikey


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## mhammer (Nov 30, 2007)

Looking at the schematic for the BYOC Tremolo, it seems there is an error. The original (and this adapted version of the) circuit works by having an oscillator drive the gate of a JFET, which is Q3, a 2N5457 in this case. The JFET is operating as a voltage-controlled resistance, placed in parallel with R9 (1k, according to the schematic). In theory, as the resistance of Q3 goes low, the gain should be increased. But the mystery is that R8 (180k) is in series with both of these, such that varying the resistance of Q3 should have negligible impact on the gain/level.

Here is another version of the EA Tremolo. You will note that there is 180*ohm* resistor in the position where R8 is on the BYOC version. Big difference from 180k. I see that the parts list in the instructions:








Also, note that while the pulsing LED does correspond to tremolo rate, it is anti-phase. That is, it gets *brighter* as the volume gets *lower*. So while you can use the LED as a tempo indicator, do not trick yourself into syncing with it, because it will be backwards.

Here's a mod I've stolen from the 1st issue Small Stone, and found useful. Get yourself a .47uf (470n, 474) capacitor of some type, and wire it up between the two outside lugs of the "Depth" pot. R10 and the extra cap will act as a lowpass filter that kicks in around 3.4hz. This "softens" the sweep as you crank up the speed, so that what I like to call the "turnaround" at the extremes of the sweep are gentler. Making the cap value higehr will introduce that softening effect at slower rates, and making it smaller/lower in value restricts the softening until things are much faster. I install it with a toggle to disable, but feel free to simply tack it onto the depth knob first and see if you like it before making it a permanent or switchable feature.

Finally, as noted earlier, the gain of Q2 is set by the effective resistance from the emitter (pin closest to ground) and ground. When the resistance of Q3 goes close to zero ohms, C3 provides a bypass around R9 for audio/AC and provides more gain across the entire audio spectrum. If the value of C3 is smaller/lower, however, that extra gain is applied to only *part* of the audio spectrum, rather than *all* of it. So, if C3 were to be, say 1uf (a value 1/10 that of the existing C3), the gain would be applied beginning a little more than 3 octaves above where it is set now. So, if the present rolloff where gain is applied were 70hz, using a 1uf cap instead would now bump the point where the gain is being "wiggled" over to around 700hz, yielding a different sort of tonal feel.


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## ezcomes (Jul 28, 2008)

from the byoc site


> This kit is based on the EA(Electronics Austrailia) Tremolo. It's a great vintage sounding trem like you
> would you set the volume level. The amplitude modulation is done with transistors, so unlike most
> opto-coupler based trems, you don't get an "on/off" sound on slower speed settings and there is much
> less current draw. It's also a lot easier to build. And the LED status light blinks in time with the speed.


i've heard of people using it as a boost...turning the depth and rate knobs down and the volume up...i've only had a brief chance to test mine, and that was the impression i got...but i still haven't given it a proper run down yet


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## mhammer (Nov 30, 2007)

I will confirm that it can operate in the fashion described.

Although the LFO circuit feeding a JFET remains the same, there are a number of different versions of the "front end", some using a single transistor, others using more than one. The BYOC version uses a JFET as an input stage and a bipolar as the gain stage. I have absolutely no idea what the range of possible gains is across the various configurations, although they all provide some additional volume to produce an "average" level comparable to bypass.

If you want it to be a "super booster", just use a toggle to connect between the '-' end of C3 and ground, and that will set the unit to a fixed maximum gain, which you can then trim back with the volume knob. This will provide more gain than simply setting the depth knob to minimum.

Taking the C3 discussion above a little further, if you had a toggle that connected a smaller value cap (say .47uf or maybe even smaller) from the junction of R8/C3 directly to ground, you could turn the tremolo into a treble booster, although you'd need to set Depth to minimum to assist that. Turn the toggle off, and presto chango, back to tremolo mode.

Very flexible design, innit?


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## The Grin (May 5, 2009)

And thus is why i have yet to build one. I would have no idea how to read schematics, but it is inevitable since i have people in my house that can teach me.


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## ezcomes (Jul 28, 2008)

with the kits...there isn't much schematic reading to do...they outline what to do and where...including pictures of the board showing where the parts go...at least the BYOC kits


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