Neovibe: SO close....

[finkployd]

I finished my neovibe tonight and to my total surprise the bulb oscillated and it gave a vibelike sound on the first try.

My problem though is that it is not at all smooth, more of a jerky abrupt jumpy kind of vibe. It smooths out a bit at lower speeds and lower depth but even that is kind of jumpy. The trem setting is kind of strange as well, it more detunes up and down. I will try to get some sound files recorded and voltage measurements tomorrow. When I was setting the lamp the dim orange glow was with the trimpot all the way up. I wonder if I need to up the resistance there, and if the jerkeyness is due to the bulb glowing too bright.

The transistors are all 2N3904, the parts are all stock from the pdf (no mods). Photocells (in fact everything) was from smallbear. Light shield is a tea light candle metal thing (eventually going to be replaced with an altoid box). Power supply is a 16v AC wallwart.

Anyone else seen anything like this?

[yeeshkul]

do the photocells face the bulb or do they look upwards?
what bulb?
what trimpot value did you use?
what value is R49?

[finkployd]

Photocells are flat against the board facing upwards

Bulb: http://www.smallbearelec.com/Detail.bok?no=716
Photocells: http://www.smallbearelec.com/Detail.bok?no=343
I also have these I am planning to try:
http://www.smallbearelec.com/Detail.bok?no=712
I don't think those are going to fit so well flat against the board, would it make sense to have them face the bulb?

Trimpot is a 200 ohm
R49 is 4.7k

It actually sounds pretty good if I take the light shield off and crank the intensity. Sounds even better if I wave a flashlight over it so I think I have the circuit right and just need to monkey around with the ldr placement and light shield. The trem setting still acts very strange but I really have no intention of using it.

[SonicVI]

There is no tremolo, it's vibrato, so pitch modulation is what you're supposed to be hearing.

[finkployd]

*smacks head*

Like Fender, I often get those two confused.

[yeeshkul]

12V/40mA bulb needs 40mA to work. That's why the trimpot can't limit the current well i guess. I use 20mA bulb and can turn the light down completely. Use either 25mA bulb or a higher value trimpot or a higher value R48 (this one is there just for protection so you won't blow the bulb turning down the trimpot).

[finkployd]

R48 replaced with a 150 ohm resister and I am back in business. Much smoother this time, especially at a more shallow depth. More depth is still not all that smooth but every sound clip I have heard of the univibe seems to match this. I still might try a 20ma bulb later, but for now I'm sticking with this.

One snafu, while playing with the trimpot, one of the external pots touched a jack (or something, I'm not exactly sure which things touched) and Q12 lit up like a struck match. I ordered a bunch of extras though so a quick swap later and I am the happy owner of a new univibe. Now I just need to stop playing Breath long enough to drill out an enclosure and get this thing mounted properly.

Thank you everyone for the help and especially R.G. Keen for such a great project.

[yeeshkul]

and after diggin' this hole don't forget it will be time to dig another one