easyvibe questions.

[jimbob]

I decided to try this easyvibe and then the Neovibe. I was curious- Why is the drive a trim pot? Also I assume since is says any dual op that the jrc4558 that I have so many of will work fine. Is there anything special about the leds used I should look for? Or are they just supposed to be really bright?

[jimbob]

Also- Ive read the 3mm low current red led goes to a ldr. Does it matter they type of ldr? Ill have to get some at the Rat shack if I want to get this done soon and they carry a small bag of differening sizes. Does it matter?

[GibsonGM]

the trim pot on the EV is to set the 'range' of the LEDs....you turn back the depth pot a little from full and adjust for best sound.  Allows a few different LEDs to be used.

I used the recommended TL064 quad OA's (from Hollis' original schematic).  The dual OA model seems to run well with TL072s. Don't know about 4558s, might be noisy....   

I suggest getting TL072's, 3mm red LEDs and the Clairex LDR's at Smallbear (+/- $10 for all this), they are optimized for use in the Easyvibe, so no guesswork...testing LDR's is a bummer.  Make sure to use the same LEDs in the power section as in the phasing optocouplers 

[Roobin]

Does using green make any difference? Mr Hollis says NOT yellow, but are greens stable?

[Torchy]

http://www.hollis.co.uk/john/easyvibe.html

Mr. Hollis' FAQ.

[GibsonGM]

People have used green, I've read. The pot is to allow you to try other LED's. As long as they are the same all around; don't use red in the power section and green elsewhere, LOL!
I stuck with the ones from smallbear, 3mm red.   Might as well; it works fine

[oldrocker]

I just built mine and used the Rat Shack LDR pack and used the smaller diameter head size ones.  I bought the mixed pack of LEDS (Bought two packs) and used the larger size red LED's.  Shrinked tube them and it works great.  I used two TL072's and two TL082's (it's what I had in stock) with no problems.  The SPDT switch works cool too.  The chorus isn't really chorus but it's a nice vibrato that's wobbly and strong.  I set the trim pot for the brightest setting for the LED's.  It sounds strongest to me with the trim set all the way but backing off on the trim might have its uses too you'll have to decide.

[jimbob]

used the Rat Shack LDR pack and used the smaller diameter head size ones

I was about to buy that same pack of ldrs but I thought in order to have enough of the small pack I would have needed to packs due to the varying sizes. I did notice there were pacs of 2 3mm red low intensity and 5 mm ones. I thought I would need the 3mms. Is that the ones you bought?

BTW- Speaking of the Rat Shack, it seems someone in the phoenix area is buying up all the damned etchant! I was luck to have found 1 store in many that still had a few bottles in stock so I had to get them. All stocked up now!

[oldrocker]

Yes you're right I bought two packs of the LDR's but I figured I'd use them for some project down the road.  I woundn't buy the small size 3mm at Rat Shack.  They don't have the brightness needed for the LDR's work right.  Use the larger standard size red LED's.  I used the larger red LED's from that pack of multi colored LED's that Rat Shack sells.  I had to buy two packs of those too.  I used all red LED's for the project including the two going to ground from the 1N914 diode.

[jimbob]

I used all red LED's for the project including the two going to ground from the 1N914 diode.

Were they the bright ones or low intensity?

[oldrocker]

I guess the bright ones.  I'm speaking of the standard red LED's you see all the time.  They're not super bright but shine with a strong glow.  The reason I used the LED's in the variaty pack is because I use those strickly.  Some of the red LED's sold individually have different voltages and milliamps and I'm not sure which one to use.  But I do know the ones that come in the variety packs work good.  I'm not sure if they're 5mm or 3mm or what voltages-amps I just know they work.

[swt]

don't know if you know this...but i'm gonna shoot it anyway. i didn't wrote this... just use the search button, as i remember it was somewhere.
here it goes:

There are two types of LDRs, those made out of cadmium sulfide (CdS) or those made out of cadmium selenide (CdSe). CdS types, which seem to be all that Small Bear carries at the moment, exhibit the problem that you are worrying about, slow decay time. CdSe types have a turn off time nearly as fast as their turn on time and are perfectly suitable for applications where a CdS types turn off time is too slow, such as phasers and tremolos, among others.
Cadmium Sulphide (CdS) reacts best to green light wavelengths, Cadmium Selenide (CdSe) reacts best to red light wavelengths.
The only real difference is in the wavelength that they respond to with CdS responding to red light (about 500 nm) the best and CdSe  responding to green light (about 600 nm) the best.


hope this help...