Neovibe Build Progress

[Joncaster]

Hey,

So i've been putting together a Neovibe for the last while (sourced local parts, boards, etc), populated last weekend,
spent a few days trying to debug a hum issue that wasn't actually an issue at all...just needed to be in an enclosure (doh!)
For some reason I forgot that external interference is an actual thing. Was probably cause I was so focused on the possibility the board had some user error in there.
At least I know it actually fired up first time, and thats not bad for my first PCB population ever.

Along the way read even more than I had, and now i've pretty much read every single thread and article on the Neovibe (and a lot of Uni/Forum/Resly stuff).
I have forgotten why I started building this in the first place, I think it's because the circuit and effect fascinate me.
Not going for a complete Trower thing (although I am a fan), but more a subtle movement as part of the song type thing.
I was fired up by a sound I heard Philip Sayce get in a live version of his song Aberystwyth (Live at The Bay)

So I just wanted to post here, touch base. Sometimes I get carried away alone with things, but its good to tell people sometimes what you are up to.

So far it's sounding pretty good,

Some resistor changes here and there,
2.2M on the input R3 (overdrives the circuit a bit more when played hard, but thats not a big issue for me. Might try a 7820 regulator and see if that opens up the headroom?)
250K output volume but no pot, just a fixed R.
Not using the Vibrato out cause I don't dig it, might sub that for a Tremolo mod and put a switch in but we'll see, I like it simple.
Biasing is going well, but that will take me time (have four different sets of LDR's to try if I really want to...
used 100E for the bias, 200E for trim. With the current LDR's theres enough to tune with.
Think I like 10-22K R49, (idea from SteveB)
Offset wise, i'm toying with R50 right now, 4k7 to 47k depending, like 22k right now.

I've been thinking a lot about the offset mod:

The name of the game seems to be the voltage divider, not the exact values of impedence, right?
So whether you add to R47 (simplified offset mod)
Or
Subtract/add from R50
Or
250K for both R47/R50 (JC offset Mod)

The outcome should be similar enough to have the desired effect?
Desired effect being to raise or lower the bias voltage so that the swing resides in the best place for the LDR's?

I tried to get into the heavier side of biasing a BJT with regard to in/out impedance and voltage/current gain and Q and...I got a bit frazzled.
But just changing R50 so far has given scope.
Will try the 250K so it changes R47 at the same time, see if that makes a difference.

So overall i'm pretty happy at the moment, it's going well:)

I want to thank RG, JC, Brad, SteveB, and all the other contributors to this forum over the years. It amazes me how much time you guys have put into answering guys here over the years.

[Joncaster]

Board was a bit neater before I started getting stuck in.
Will redo leads when it's time to box.

Light shield is from a little tin for gift cards I found.
Prefer the semi shiny metal to the shinier tin foil.

Lamp is 12V 30mA
LDRs are 5k - 1M

Just need a 16mm pot for the depth and I'm ready to box.

[Governor]

Looking good mate, I've just started a neo build myself - currently populated the pcb except for the LDRs and lamp.  I've been trying to find out how high to mount the LDRs and lamp as I would hate to cut the pins too short if I stuff it up! (I live in Australia so the cost of freight and delivery time from Europe I really don't want to do again). I'm following the geofex instructions to the tee but I just can't find how to mount these, what heights and angle did you mount yours above the pcb?

Thanks for posting your progress, make sure you keep us posted on how you go.

[Joncaster]

Looking good mate, I've just started a neo build myself - currently populated the pcb except for the LDRs and lamp.  I've been trying to find out how high to mount the LDRs and lamp as I would hate to cut the pins too short if I stuff it up! (I live in Australia so the cost of freight and delivery time from Europe I really don't want to do again). I'm following the geofex instructions to the tee but I just can't find how to mount these, what heights and angle did you mount yours above the pcb?

Thanks for posting your progress, make sure you keep us posted on how you go.

I mounted them as flat as they would go (their lead spacing is a bit smaller than the boards), having read that flat with reflected light was pretty traditional.
I planned to do a foil box anyway.
But I left a bit of lead sticking out the bottom (so I cut off about half the lead length), so I could pull them up if needed. Just did a light solder to keep them in place till I was happy.
I tried them facing the light more but it took away something in the sweep.
The lamp I just kinda gave it a bit of slack, maybe 1mm wire above the board, but didn't think too hard about it. But I did buy 2 of each of 4 different types, so wasn't worried with them.
I tried that one first and havent bothered with others...maybe I should...

The thing I did do that helped a lot was mount the board on standoffs, so that the wires sticking out the bottom had clearance.

Ended up trying all four sets of LDR's and came back to the first ones I stuck in (although I did move them to the further back set of holes). They went the highest Dark resistance, and my bias is set very dim (I find it's swirlier and more liquid in the dimmer settings). The brighter the bulb flashes, the more it starts moving into Wah territory.