EA Trem - A little help from the masters...

[Blues_Boy_4096]

OK, here's the thing.

I've built an EA tremolo based on the PCB layout from ROG.

It works fine except from the Depth control - it isn't much noticed...

I've measured the voltages on Q2 and I have a changing voltage at the Gate (from around .5 to 2V), but nothing at the Drain.
Is it supposed to be like this or is there anything wrong?

Thanks

[gez]

Varying the resistor chain from the LFO to the FET which does the modulation will get you more depth.  Plenty in the archives about this, and it's mentioned in the original magazine article (its on-line). 

Alternatively, link to the schematic and I'm sure you'll get some advice.

[mac]

I suggest you to use trimpots everywhere in the oscillator. Some fets just don't work with the original resistor.
Looking at GGG schematic, I'd replace r7, r8, r10 with trimpots, use different fets, like BF245A which has enough gain and moderate VGSoff. Also add a resistor from the source to ground like in the original Phozer. If you get distortion increase r5. Play with c5-c7 or just replace one of them with a 0.47 or 2.2 cap.

Actually I'm working with the original PHozer which uses the same oscillator. As stated at ROG, in its stock form the effects just works. I modified the oscillator to get almost 3sec between peaks, more deepness even at high rates, and wha. Have to experiment a little more.

mac

[nobody]

Varying the resistor chain from the LFO to the FET which does the modulation will get you more depth.  Plenty in the archives about this, and it's mentioned in the original magazine article (its on-line). 

Alternatively, link to the schematic and I'm sure you'll get some advice.

Got a link to the magazine article? I've been trying to find it and I can't. The link at GGG is broke.

[markm]

Check out Casey's gallery.
Nice stuff in there! 

[nobody]

nice!!!! Good stuff in there.

Thank you!

[gez]

Varying the resistor chain from the LFO to the FET which does the modulation will get you more depth.  Plenty in the archives about this, and it's mentioned in the original magazine article (its on-line). 

Alternatively, link to the schematic and I'm sure you'll get some advice.

Got a link to the magazine article? I've been trying to find it and I can't. The link at GGG is broke.

I'm afraid I don't.  Can anyone help?

[markm]

Right this way; http://aronnelson.com/gallery/album57