Easy Vibe

[Hal]

Hey, everyone!
Looking at http://www.geofex.com/PCB_layouts/Layouts/easyvibe.pdf I am tempted to buy all the parts and build it.  looks hot hot hot.  However....small problem with it.  What is LDR 1-4 ?  Steve sells "Clairex CL9P4 Plastic-cased photocell for the Easy Vibe and other modulation effects. Fast response, Dark Resistance 20 Meg, Light Resistance 20K"

is that it?  Also, should I use the TL072's or TL062's ?

thanks a lot!

[Doug H]

My understanding is that tl062's draw less current. So they will help with battery life, although tl072's will work too. John designs very efficiently that way.

I meant to build that sucker 3 years ago and still haven't gotten to it...

Doug

[MartyB]

The commercial optoisolators might be the very best, but they're also pricey.  I used 4 matched flat-faced LEDs from a photocopier wand and 4 15ohm photoresistors from Mouser Electronics.  I superglued the LEDs to the photocells and bound each unit with heatshrink.  Mine worked great - and cost me less than $2.

[MartyB]

Sorry, that's 15kohms.

[JohnM]

I used the recommended parts from Small Bear and it worked fine.  I just bent the components to face each other.  You have to cover it when out of the box, but otherwise the inside of the box is dark enough so you don't have to otherwise wrap or sheild the LED/LDR.

[Johan]

the TL062 will work with lower voltage than the TL072 aloving you to run the batterys a little longer. otherwise they are just about the same...the 62 will work down to +-2volt....

Johan

The TL08x is the standard, TL-07x low current, TL06x low voltage and TL05x "improved specs." (?)

[smallbearelec]

While I always like to sell from my own stock, John Hollis, the designer of the Easy Vibe, has said that tweaking of the 1K trimpot permits using a very wide variety of LED/LDR combinations.

[Hal]

Thanks a lot!

Just one more question JohnM - the grey "mexico" box in the bottom left...is that a trim pot?  If so, I've never seen one like that!  Would a standard one work?

Also, what do those 2 other LEDs do ? clip?

Last...how does it sound, man?  worth building?

[petemoore]

Gonna build another one that works right.
 Mine works but has this cool added feature of the sweep sound fades out after 45 xeconds to a minute, I 've a power interrupt switch to 'restart it.
   Actually I've used it on recordings and it's really cool this way..like yer Buzz' wears off...hardly even notice if you weren't paying attention till it comes back on a gain.
 The efkt IMO is captivating.

[Bill_F]

I used the recommended parts from Small Bear and it worked fine.  I just bent the components to face each other.  You have to cover it when out of the box, but otherwise the inside of the box is dark enough so you don't have to otherwise wrap or sheild the LED/LDR.

Hey John,

I've been thinking about building this. Do you like it? Can you get that Trower sound out of it?

Thanks,
Bill

[Paul Perry (Frostwave)]

JohnM, that's a great pic! (and doubtless a great fx). What sort of camera do i need to get this quality close up?

[MartyB]

JohnM,

 Nice build!  You still might consider shielding the LED/LDRs since there is bleed from one LED to the other LDRs within the box.  I would think stray light would blunt the effect to at least some degree.  Heat shrink, paper tube, electrician's tape.  I blackened('Sharpie'd) the back side of the LEDs to prevent shine out the back of the shrinkwrap.  Mine are the pale green variety.  I wonder what the peak wavelength sensitivity of those LDRs is.  

MartyB

[JohnM]

Thanks a lot!

Just one more question JohnM - the grey "mexico" box in the bottom left...is that a trim pot?  If so, I've never seen one like that!  Would a standard one work?

Also, what do those 2 other LEDs do ? clip?

Last...how does it sound, man?  worth building?

It's an 18-turn trimpot, and it's a pain.  PLEASE just use a normal one.

LEDs aren't for clipping, see GEOFEX article.

I recorded some clips at:
http://home.earthlink.net/~johnecat64/soundpage1.html

[JohnM]

JohnM, that's a great pic! (and doubtless a great fx). What sort of camera do i need to get this quality close up?

No camera, I used my scanner!  :-)

[JohnM]

I would think stray light would blunt the effect to at least some degree.

My intuition says it won't, but I've been wrong before!  I'll try it sometime.  (The original univibe has 1 light and 4 LDRs, that's why I think it won't matter...)  Definitely, leaving it uncovered out of the box does blunt the effect a lot.

[dubs]

The leds are v.low brightness so there would be very little leakage to other ldrs.

is there any way to improve the range of the pots? It's all happens in the last quarter turn of the pots. Perhap stick a fixed resistor in there? What values would be best?

this is a awesome sounding effect. Build it!

[george]

I would think stray light would blunt the effect to at least some degree.

My intuition says it won't, but I've been wrong before!  I'll try it sometime.  (The original univibe has 1 light and 4 LDRs, that's why I think it won't matter...)  Definitely, leaving it uncovered out of the box does blunt the effect a lot.

all the LEDs flash on and off at the same time (they're all hooked up to the LFO via the 1K trimpot) so shielding individual LED/LDR's won't make any difference.  Still it's pretty easy to put heatshrink tubing (pref black) over them, and this might make it easier to debug the effect with the PCB out of the case ...

The 2 LED's in series with the silicon diode are a convenient means of providing a bias voltage for the input signal to the 4 LED's. A diode has a forward voltage when it's conducting which is constant with varying current and applied voltage, thus the Easyvibe opamp inputs have bias voltage that remains constant even if the battery is getting a bit flat.

hth ...

[MartyB]

George, I don't think the LEDs are supposed to flash synchronously.  In fact viewing mine there is a visible difference in the timing of the flashes.  I'm not into circuit theory, but why would we need four different pairs of emitter/detector?  If they're in synchrony, then why not just have one LED?  Does that make sense?  As for me being fastidious about stray light, I haven't tested the effect of shielding on the vibe sound. It comes out of habit from dabbling in amateur astronomy - a hobby that's taken a back seat to music   .

[MartyB]

Hey George, You're right!  I just checked the layout of the original and there's just one incandescent bulb!  My "visible" delay in flashes is either a hallucination or there's something wrong with mine.  Anyway it sounds great.

[petemoore]

My EZ vibe needs attention, but as it is on perf, I need [can't find the original sheet I had] the schematic drawing of the ckt.
 Anyone know where I can find just the schematic drawing?