vibe light bulb

[Chico]

I know that there has been some members of this forum indicating a difficulty in finding 25 ma bulbs for the neovibe, etc.   Some have even indicated that the more common 50 ma bulbs do not sweep as well.

I was visiting JC Maillet's excellent site http://www.lynx.bc.ca/~jc/pedalsUnivibe.html

Somewhere in his discussion of the univibe+, he mentions the use of a Radio Shack bulb, Radio Shack part #272-1139.

I checked out this part on the Radio Shack Website, see
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F011%5F004%5F007%5F000&product%5Fid=272%2D1139

The web page lists this bulb as drawing about 25 ma.  However, no max operating voltage is given.

JC (apparently) runs his univibe + at 24 volts, so I would assume that the bulb can handle the voltage.

Just thought that I would pass the info along.  I am still about a month out from my univibe build, I have not even started my layout.  But I wanted to start getting my parts lined up.  Particularly, I wanted to build my dark box for the light bulb and ldrs while doing my layout so that I am sure everything will fit.

I went ahead and ordered one to test (its only 1.29 US), but seeing that I am early in the build, it will be a while before I can report its capability.

Anyone else out there use this bulb?


Best regards

[moosapotamus]

Order a few extra of those Radio Shack bulbs. It might blow if you don't have the trimmers set properly the first time you power it up. Better safe than sorry. :wink:

~ Charlie

[Eb7+9]

I know that there has been some members of this forum indicating a difficulty in finding 25 ma bulbs for the neovibe, etc.   Some have even indicated that the more common 50 ma bulbs do not sweep as well. ... JC (apparently) runs his univibe + at 24 volts, so I would assume that the bulb can handle the voltage.

Hi Chico,

The voltage across the circuit is not applied directly to the bulb so you can use a variety of bulbs as long as you adjust the gain of the bulb driver accordingly ... two of the early mods in my clone consists of (i) replacing the single device by a Darlington pair so the driver device doesn't get too hot and (ii) there's a vertical offset adjustment on the bulb driver circuit which allows the bulb turn-off point to be made adjustable, aside from the gain adjustment which determines the amount of brightness travel - combination of both is crucial in my opinion for getting a nice response out of the circuit ...

... the Radio Shack bulb that's listed on my Univibe page is rated for 1.5v 25mA - I guess that represents maximum or nominal brightness ratings ... I've tried a few going all the way up to 12v 40mA with no huge difference in performance - so there's a range of bulbs you can use but you don't go too high in current rating (the current rating matters more than the voltage one) ... I also recommend buying a few bulbs since they are easy to blow at first - it takes a while to get a hang of the gain control on the bulb driver - very easy to blow the bulb if you power up the circuit and the gain is maxed out (I've done it so many times) ... if you use my PCB layout as guide you'll have to shred the wires that are attached to the leads coming out of the glass bulb so that the bulb sits upright inside the circle of cells ... I also drew my layout so a Kodak film canister can be used to shield the photocells from outside light ...

I've had the Vibe running at 24v, 15v and 9v with no huge difference in sound - makes sense considering most of the stages are operating at unity gain ... try what's available to you - maybe test things out with a few 9v batteries at first to see if you find any preference ... the Shin-Ei "Resly-Tone" and JAX "Vibro-Chorus" likely operated at 9volts ...

Let us know how it turns out !

... JC

[Eb7+9]

... dblpst

[dr]

.....I used that same Rat Shack bulb in my Neovibe-it works great.....just leave the ldr's legs long so you can tweak their distance from/towards it to get what you need.....I tried others at various ma. ratings,and they all could be made to sound great depending on where you pointed the ldr's.....sounded best not pointing directly at or near the bulb.....just experiment!......

[Chico]

Thanks for the tips everyone.  This is my next main project, and I look forward to digging into this one.