LND150 Tremolo?

[Ten Over]

For that arrangement I would add another FET as a source follower, exactly as in the Vibro-Champ.

You may want to increase that 68K because those LND150's can swing nearly rail to rail. The 150K that I showed may be a little too much. Or not.

[Mr. Lime]

For that arrangement I would add another FET as a source follower, exactly as in the Vibro-Champ.

Thanks so much, I will add that circuit to my upcoming project.

For that arrangement I would add another FET as a source follower, exactly as in the Vibro-Champ.

You may want to increase that 68K because those LND150's can swing nearly rail to rail. The 150K that I showed may be a little too much. Or not.

I'll keep in mind to experiment with that resistor, 100k seem to be a good value to start with I guess?


Just to mention; I came across the Mesa Tremoverb schematic. They used an 555 Oscillator IC with a LDR just like a common stompbox.
I wonder why I have never seen a bias wiggle tremolo with different waveshape options?
Not sure if a squarewave would be that appealing but sawtooths or ramps might be interesting?

[martin manning]

68k or 100k will work. I'd experiment, but I wouldn't make it less than 68K. You will get different levels of intensity if you keep the same 25k pot, too.

I've wondered what different waveforms would sound like too. I guess it would be easy enough to find out by connecting a function generator to an amp ;^).

[Ten Over]

The value of the Source Follower tail resistor and the Intensity Pot have a significant effect on the useable range. The 68K Cathode Follower tail resistor and the 25K Reverse Audio pot typically yields an on-off tremolo by the time the knob is at 8. The next value up for the guys that designed this is 100K, which would be better for the max. end of the range. The stock setup is barely noticeable until the knob is at 4. A 100K tail resistor would move the min. end of the range up, which is not desirable. The next resistor down is 47K which would be good for extending the min. end, but bad for the max. end of the useable range, so they seem to have compromised at 68K.

A 50K Reverse Audio pot only has what I would consider to be a useable range from 3 to 5 with a 68K Cathode Follower tail resistor. 25K Reverse Audio pots don't seem to be readily available in our usual 24mm size, but they are available in the snap-in style. I cut a little PCB and mounted that on a snap-in pot in order to get the data for a stock Vibro-Champ.

The first schematic I posted on page 1 has what I would consider to be useable range for the entire sweep and it uses a readily available 25K Linear 24mm pot. Of course, others may not have the same opinion about just what a useable range is.

Lots of different Source Follower tail resistors will work, but the useable range on the Intensity pot may not be optimal.

[Masco]

Here's the CC trem: