Neovibe lamp - ldr arrangement

[alfafalfa]

So I'm building the Neovibe finally, had a lot of trouble finding a suitable lamp . Now I used a 12 volt 30 mA minilamp and 4 ldr which can be moved back and forward. Hope it's going to work.


So now it's time to cut the film capsule box and cover the whole arrrangement with the removable lid.

Has anyone so far encountered any hum from the ac coming right into the board ?

Alf

[wlrs]

I tried an ac transformer on my neovibe and it humed real bad so I went with something else. If you move your LDR closer to the light it will work better. I used some black tape to cover my LDRS I wound the black tape back wards around my first 2 fingers to make a O and put some tape on the top to cover. I have pics but I dont know how to post them
I guess we all need some help ah :>) ...
walrus

[alfafalfa]

Thanks Walrus for the black tape advice but I'm going to proceed as R.G. wrote in his description.
You take a black film canister saw of half and cover the lamp and Ldrs with it . So the whole assembly will be in the dark.

Pictures you can post by putting them on a site : I use Photobucket, then you paste the url on this site ( first click the picture icon ) in your message.

Alf

[alfafalfa]

Well I finished my Neovibe and am biasing the lamp. I had the wrong trimpot in, so I put a 200 ohm resistor in. The lamp won't come on only when I shortcircuit the resistor, so 200 ohms is too much .
When it's zero the lamp comes on but  it won't shine brightly.

My question is how bright does the lamp have to get ?
It's a 12 volt   30 mA lamp ( see picture) . It  will also be rather dim when I connect it e.g to a 9 volt battery.
So do I have the wrong lamp ?
The lfo works well  and so does the speedknob.

[Aharon]

I built the NeoVibe a while back and run ito a similar problem (me thinks) and as always RG to the rescue...........he suggested replacing the 200R trim with a 500R......I had a 1K in hand so I did and it worked fine.

Here's the thread......
http://www.diystompboxes.com/smfforum/index.php?topic=49667.msg370448;topicseen#msg370448

Aharon

[Minion]

Maybe try a super bright LED....you will get more light with less power and voltage and without any heat.....

[alfafalfa]

That could work too !

I never had any problems etching the board. But then I have now finally standardized my etching procedure after a lot trial and error


Anybody else tried a led , does it have the correct risetime?

Alf

[Aharon]

I would not think so............
Try a bigger trim.............
Aharon

[John Lyons]

An LED will not work for the Neovibe. The viewing angle is much to steep to feed light to 4 LDRs.
Also the speed that an LED turnes on and off will through off the Neovibes characteristic feel.
Not to mention that the bulb uses 12v and an LED uses 2v or less as well as the current difference.

Do a search for SteveB and Neovibe and you will find pics of a monster sounding Neovibe he built.

John

[alfafalfa]

Thanks John , I found the thread and it has a lot of good info.
But one thing I haven't been able to trace so far: how bright is the lamp supposed to get ?

I noticed , Steve B also used a small "grain of wheat " type like I used myself.
I sent him a personal message and hope he will respond .
He gets an awesome sound !

Alf

[John Lyons]

I used a radio shack 12v/25ma bulb. I think SteveB did as well. His photo may have been of another one though as it's an old photo.
Steve is a nice guy, he helped me with mine...
The distance and spacing of the LDRs can make a differece in the sound of the neovibe. I went with something like steveB's but I spaced the LDRs so they all "see" the bulb at thye same angle and see the broad part of the filament as opposed to the side if the filament which looks like a dot (hard to describe that...)
The bulb should be dim and orange with the depth set at 0 and the bulb should be bright and white at max depth but not you can set the trimmer to find a nice max setting. Sometimes if the bulb is too bright you can get a thump sound...

The Problem with the Neovibe is that there are a few different ways you can make it. They all sound different and you can use several different specification parts to get to a "good" sound. The LDRs are a big part of how mine came to life. I got a set from a friend that really made a big difference in how it sounded. Fast and wide ranging LDRs seem to sound best  in my opinion. But which ones to buy? I don't know...that's part of the problem and confusion, there isn't a specific part that you can go out and buy that is listed anywhere.
All the info is in the threads here on the forum, you need to dig a little though.


John

[alfafalfa]

John ,

I got a reply from Steve b  and he said he lamp was a Radio Shack type and was as bright as a torch with weak batteries.
So I'm going to try my setup the way it is and will soon find out if it's getting bright enough.
I think I understand what you mean with the quote below .

but I spaced the LDRs so they all "see" the bulb at the same angle and see the broad part of the filament as opposed to the side if the filament which looks like a dot

All the ldr's are on long wires so I can bend them quite a lot.

Alf

[wlrs]

I'm sorry I forgot to mention that the black tape was temporary so I could do my final tuning 

[RedHouse]

Interesting pic from Fulltone's website. This is said to be a picture of the LDR's and Bulb under the light shield on a real vintage univibe, which BTW is covered by a shiny reflective tin cover (not quite a black film canister):



If true, this kinda suggests to me that the real vibe functioned a bit more from the bounced ambient light within the shield and perhaps less from the direct light from the bulb although the pic shows that the bulb is oriented so in such a way that some direct light can reach the faces of the LDR's from an angle.

I'll have to try it myself, I've mostly used the typical arrangement we all use, LDR's facing Bulb (sometimes at slightly off-angle).

[R.G.]

De-fogging time again.

The photo from the fulltone site is of the LDR arrangement on a real Univibe. They did use a shiny-inside bent-tin enclosure, and it was indeed to get a much more diffused light on the LDRs.

I came up with the film cannister to get an easy light tight enclosure. In my first instructions I suggested lining the inside of the cannister with aluminum foil. However, pointing the LDRs at the lamp works.  I also later came up with the tin-can light enclosure, which uses scissors-cut tin can to make the enclosure and glued-on aluminum foil for the light mixing chamber. If you're going with the tin-can style, mount the LDRs flat as in the original. The PCB has holes drilled in two places to allow both horizontal and vertical mounting.

Confusion about the vibe creeps in two ways: either by "experts" hyping their wares or by newbies opining about why things happened. Opining and hyping get accepted by even newer newbies and extended. This causes what might be called "information drift".

Wide range and fast is correct for the LDRs. These are competing requirements in LDRs, so every LDR is compromise. LDRs are so rare that my advice has always been - put in what you can get now, and search for the perfect ones while you enjoy your pedal.

Real univibes had a wide range of variations too. The key to a good sound is wide range, fast LDRs and tweaking the mix of dry and wet sound at the output mixer.

As well as doing the rest of the build correctly, of course.

All for now. Gotta go build fences.

[alfafalfa]

This is very interesting  guys, so I tried  a little modding myself.

I just cut off a piece of aluminium foil and put it loosely inside the film canister and ..... got  a helluva noise ..because the foil shortcircuited some of the ldr's .
So I took out the kining on the inside and bent the ldr's so they are facing upwards  halfway and  put some foil in the canister cap.
So now it's working again and I must say I do like the difference in sound ; it seems a more pronounced effect.

I'm going to experiment a bit more . This thing can  benefit a great deal from experimentation.

Alf

[RedHouse]

Same results here. I'm now experimenting with shrouding the bulb and letting the LDR's actually work off of the reflected light from the roof of the light shield.

I also am having a theory that part of it might be the bulb's contribution, when the LDR is not directly lit, the bulb is able to be run a liitle hotter, seems like more within it's changable brightness range.

I think (I'll know more later when I can profile it) that bulb's are faster at changing brightness when it goes from a definate on-state, the dull orange glow-to-bright as compared to when it goes from nearly off to some state of on'ness.

BTW, I wasn't knocking the Black Film canister idea RG, I was just pointing out the original had a different setup.

[RedHouse]

De-fogging time again....Confusion about the vibe.....

I re-read your post a couple times now and I can't figure out what the fog and confusion is you're speaking of RG, wha'sup?

[R.G.]

I re-read your post a couple times now and I can't figure out what the fog and confusion is you're speaking of RG, wha'sup?

Well,

Maybe try a super bright LED

That could work too !Anybody else tried a led , does it have the correct risetime?

I would not think so............ Try a bigger trim.............

how bright is the lamp supposed to get ?

Fast and wide ranging LDRs seem to sound best  in my opinion. But which ones to buy? I don't know...that's part of the problem and confusion, there isn't a specific part that you can go out and buy that is listed anywhere.

This is said to be a picture of the LDR's and Bulb under the light shield on a real vintage univibe ... If true, this kinda suggests to me that the real vibe functioned a bit more from the bounced ambient light within the shield and perhaps less from the direct light from the bulb

[Tony Forestiere]

R.G
As usual...you are teaching the man HOW to fish.