reagenerated tremolo Transmogrifox?

[Arn C.]

http://www.geocities.com/transmogrifox/rEAgenerated_Trem

What transistor is used for the unlabelled transistor in the schematic?

Thanks!
Arn C.

[calpolyengineer]

Well I'm only guessing here, but since its an NPN and the only other NPN in the circuit is a 2N5089, it probably is too.

-Joe

[Arn C.]

Bump!  Anyone else know what transistor it is?  Calpolyengineer, thanks for your guess, I was looking for a more positive answer on this.  Again thanks!

Arn C.

[lovekraft0]

Don't take my word for this, but if I understood the explanation correctly, nearly any GP silicon transistor will work as the CCS. Hopefully Transmogrifox will weigh in shortly, but I was planning on using a 2N5088 (when I get around to building this one), simply because it's what I have on hand.

[soggybag]

I like the name what does this do exactly, or should I ask what makes this different from a regular tremolo?

[Transmogrifox]

Sorry for the delay.  It's been a while since I've had a chance to browse the forum (just been busy).

A previous post was correct:  the unlabelled transistor can be any general purpose npn device.  I recommend the 2N5089 or similar because it's low noise and high gain.  The higher the gain, the higher the impedance seen at the collector in this configuration (and this is what we want).

You can also swap transistors in the oscillator section with whatever you have on hand, though you may need to change the collector-base bias resistor (3.3M) to something else to get it to start up.

I think the JFETs are the most flexible as far as parts swapping.

To Soggybag:
There is nothing that makes this different from a regular tremolo.  It's actually supposed to be very regular.  It's based on the ever-popular EA Tremolo.  The oscillator and general sound of the EA is grEAt, but it is difficult to get good depth.   One of the problems is that the resistor in the emitter/source (depending on which version of the EA you build) leaves the minimum gain at something audible.  I had guessed that putting a constant current source with a very high impedance in the source to bias the amp stage would eliminate that factor, and make the AC gain 99.9999...% dependent on the equivalent resistance on the JFET variable resistor.

In short, the rEAgenerated Tremolo is an EA Tremolo that has been re-worked to get a deeper depth.  In addition, the volume pot was moved from the end to the front so that you could prevent it from distorting with high output pickups.

I have been happy with my prototype.  It does get deep, and makes for a nice little effect to stomp every once in a while.  I have been promising to make a PDF project file of it.  It will take a while to complete since I tend to get into the outdoors more during the summer.  It's a hard trade-off between building stompboxes and walking around on mountains...but really, how many of you have the opportunity any given evening of the week to go on a trail run to a cabin by a lake, paddle a canoe around to a good view of a black bear grubbing near the shore...and be back home in time to grill some steaks before hitting the sack?  Hard trade-off.