Neovibe Question ...

[StevanL]

May as well say Hi first as this is my first post 

So, I have built a Neovibe and have now got it working after a bit of debugging. It does sound really nice, but I have
a couple of questions that maybe someone here may know the answers to:

So the bulb throbs nicely with the Kodak lid off, but I notice that it flashes much brighter as the speed increases. I am getting a really nice deep vibe tone with the speed around 12 o' clock, but as I slow itdown, it gets a bit thinner. (I am guessing this is because the bulb isn't getting as bright) Is this normal ?

I have fiddled with the trim pot too.

All components are stock (from Small bear, and using GGG pcb) apart from the bulb which I got at banzai. (all transistors are 2N3904's)

Thanks in advance.

[Jaicen_solo]

This is a normal side effect of the use of an incandescent bulb. The brightness increases because the bulb is repsonding to the average current, rather than voltage. Something to do with the resistance of the bulb.

[StevanL]

Thanks, I guess thats what the intensity knob is for then 

[plankspank]

So the bulb throbs nicely with the Kodak lid off, but I notice that it flashes much brighter as the speed increases. I am getting a really nice deep vibe tone with the speed around 12 o' clock, but as I slow itdown, it gets a bit thinner. (I am guessing this is because the bulb isn't getting as bright) Is this normal ?

This is normal- it is inherent in the design of the LFO circuit- as the speed increases, the amplitude of the LFO increases. The 2 diodes back to back limit this increase. This is all explained in RG's Univibe write-up.