Adapting the Lera circuit to the Neovibe

[Solidhex]

Yo

  Getting ready to build another neovibe and wanted to try something different. I was planning on doing the single pot LFO mod so I could use an expression pedal but after checking out the LERA circuit I think I might want to go for that instead.
  Here's a link to the single pot LFO mod article:  http://www.geofex.com/circuits/ldrlfo.htm
And one for the LERA: http://www.geofex.com/article_folders/lera/lera.htm
   Had something I wanted to confirm with someone else out there before start. The LERA uses a 10k pot to set the minimum resistance controlling the maximum speed of the LFO. To use the LERA with the Dual resistances needed by the Univibe you would need to use a dual Opto AND also a dual 10k pot in series correct?
  Also could you just tap into the Neovibes board to power the LERA? Would it need its own 9v supply?
I did a search and found other people had looked into this but these points weren't discussed.

Thanks! Brad

[rhdwave]

Hey Solidhex,

I could be wrong, but it seems that it would be easiest to utilize the LERA if you went ahead and made the single speed pot mod as well.  This way, the LERA could be hooked up i would think via a switching jack to the speed pot in lieu of an expression pedal.  I was thinking of doing this as well on my next vibe project...

[danielzink]

Being as there's already a lot going on with it - I'm wondering what we'd get with this mod as far as an audible difference in a Univibe ?


Dan

[rhdwave]

I think the idea is that it's like an automatic movement of the speed control...so it's constantly ramping up or down depending on which way you set it with the switch...

[danielzink]

I'm going to give this a shot here in the next week or so.

I've DIYLayout'd a PCB for it and will etch it soon.

I'm going to try and implement it with a re-housed chicken salad which I'm already modding to use RG's suggestion for getting rid of the dual gang pot.

I've searched the mod (LERA) to death on this board and others......some say it works great and some say that there's no in between with the speed...it's either really fast or really slow.

There's the suggestion that the opto impedance should be close to the existing speed pots impedance....and that may be a source of the issue.

We'll see !



Dan

[Solidhex]

Hey Solidhex,

I could be wrong, but it seems that it would be easiest to utilize the LERA if you went ahead and made the single speed pot mod as well.  This way, the LERA could be hooked up i would think via a switching jack to the speed pot in lieu of an expression pedal.  I was thinking of doing this as well on my next vibe project...

Looking at the schems you can see in the LERA there is a 10k pot between the opto and the phaser's normal speed control. Since the Neovibe requires 2 separate resistances to control the speed it looks as if you'd have to not only use a dual opto like the VT5C3/2 in the LERA but also use a dual 10k pot between the LERA and the Neovibe's speed pot pads to adjust the "max speed".

--Brad