05.19 - LaVache and Cosmopolitan

[bigmufffuzzwizz]

this is all ive ever wanted

[madbean]

I posted this in the wrong thread, and meant it as a follow to go in this one!
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Here's a few more details: it's based on the Escobedo Wobbletron and has a bunch of mods. First, instead of using a transistor to create the vibrato, it uses a complete implementation of the Univibe LFO. This drives a small 18v lamp. The advantage of this over a transistor or LED based approach is the smoothness of the ramp up and down of the actual lamp. It's more natural and less choppy than an LED, I went with a tiny lamp to make this thing fit into a 1590B with ease.

Next, it has an added JFET input buffer and a simple bi-polar output gain stage. Lastly, it has a switch so that you can change between vibrato and pure tremolo.

I'm looking into getting a supply of the specific lamp I'm recommending. It will actually require a Road Rage board, too (or a charge pump, at least).

[sgmezei]

Looks awesome Bean! Any idea when the BOM will be up. I'm doing some ordering....

[crash]

I have all the components for the LaVache, except the 3.3M resistors.  Could I use 2.2M resistors for these instead, or will that mess up the biasing?

[sgmezei]

You could put the 2m2 and another resistor in series, twist them together like a tipi to get as close as possible. I will let one of the smarter chaps comment on the biasing though.

2M2 + 1M1 = 3M3 or if you have a 1M you can get close at 3M2

[crash]

I suppose I can do that in the short term, then put a 3.3M the next time I place a component order.

[highway jones]

Cosmo's are gone..  Crap!  i waited too late.

[madbean]

I'll have a few more soon. I'll etch a new panel in a couple of days.