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Topic: Neovibe lamp - ldr arrangement (Read 972 times)
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alfafalfa
Posts: 247
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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
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« Last Edit: September 08, 2007, 10:02:44 AM by alfafalfa »
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wlrs
Posts: 45
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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
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alfafalfa
Posts: 247
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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
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alfafalfa
Posts: 247
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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.
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Minion
Posts: 197
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Maybe try a super bright LED....you will get more light with less power and voltage and without any heat.....
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alfafalfa
Posts: 247
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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
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Aharon
Posts: 833
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I would not think so............ Try a bigger trim............. Aharon
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Aharon
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John Lyons
Posts: 3066
Basic Audio
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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
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alfafalfa
Posts: 247
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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
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John Lyons
Posts: 3066
Basic Audio
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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
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alfafalfa
Posts: 247
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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
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wlrs
Posts: 45
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I'm sorry I forgot to mention that the black tape was temporary so I could do my final tuning
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RedHouse
Posts: 693
Brad B
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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).
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« Last Edit: October 04, 2007, 08:08:01 AM by RedHouse »
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-Brad (this is where stuff goes that nobody wants to read)
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R.G.
Posts: 7808
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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.
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R.G.
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alfafalfa
Posts: 247
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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
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RedHouse
Posts: 693
Brad B
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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.
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« Last Edit: October 04, 2007, 03:58:40 PM by RedHouse »
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-Brad (this is where stuff goes that nobody wants to read)
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RedHouse
Posts: 693
Brad B
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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?
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-Brad (this is where stuff goes that nobody wants to read)
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R.G.
Posts: 7808
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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
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R.G.
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Tony Forestiere
Posts: 238
"F" and a lot of vowels
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R.G As usual...you are teaching the man HOW to fish.
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Duct tape is like the Force. It has a light side and a dark side, and it holds the universe together. Carl Zwanzig
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