Schaller Tremolo build report

[RickL]

Built using the Topopiccione layout here: http://topopiccione.atspace.com/PJ20SchallerTremolo.html

The build was fairly easy and it fired up perfectly from the start.

It's a nice choppy trem, fairly quiet, very usable range of speeds. The Range switch is a nice feature. Top speed with the Range switch engaged is almost, but not quite, into Ring Mod range.

I found that a 100k pot works pretty much the same as a 50k for the Depth pot. The bottom quarter of the rotation with either value seems to have no effect. If you were picky you might want to add about a 10k or so resistor in series with the Depth pot to minimize the dead part of the rotation.

Bypassed volume seems to be just about the same as the engaged volume. I wonder if the volume could be made variable by replacing R4 with a 2k pot with the wiper going through a cap to ground (like the Fuzz pot on a Fuzz Face).

[Zero the hero]

Congrats and thaks for the report!

I still have to box this trem, I'm working like a mad, and I have no time at all...

[markm]

What's the sound like?
Is it similar to the Pulsar with a choppy type trem?

[Bernardduur]

What kind of transistors did you use? I have some problem getting the right ones here (already tried BC550B's and BC546B's and both give only the bypass signal).....

Also, is the 5.8k value resistor important? I can only get 5.6k here

[RickL]

I used 2N5088s. I don't see why it wouldn't work with just about any hight gain transistor. I suspect even 2N3904s would work.

I made up a 5.8k by adding a 200 ohm resistor in series with a 5.6k. I suspect that a 5.6k would work fine.

I haven't listened to my Pulsar for a long time so I can't give an exact comparison, but it is a choppy type tremolo of the same general type. Not exactly machine gun choppy but you won't mistake it for a sine wave type. Square wave with slightly rounded corners might describe it.

[Bernardduur]

OK, thanks!! Guess my layout must be wrong then..... I will build it again!

Edit: Call me stupid; I've found it!

[Zero the hero]

Bern, did you find why it's not working?
I used a 5k6 with no problem at all, and all BC54x ( with 6 <= x <= 9 ) should work fine.

[Bernardduur]

I used a stupid layout (made by myself) that turned a couple of trannies the other way to make space......... they were in the other way around...... 

It only gave the bypassed signal, the depth pot worked (as it reduced the signal when turned open).

Now I used a lot of trannies and they all seem to work. BC550 B and C just work, 549 B and C, 548 B and C all work

[mongo]

I used 2N5088s. I don't see why it wouldn't work with just about any hight gain transistor. I suspect even 2N3904s would work.

I made up a 5.8k by adding a 200 ohm resistor in series with a 5.6k. I suspect that a 5.6k would work fine.

I haven't listened to my Pulsar for a long time so I can't give an exact comparison, but it is a choppy type tremolo of the same general type. Not exactly machine gun choppy but you won't mistake it for a sine wave type. Square wave with slightly rounded corners might describe it.

does the pinout of the 5088's is the same as the trannies marked on the layout you used?

Andy