Little Worker - Yet another easy phaser

[Crontox102098]

Introducing the Little Worker a easy 2 stages LDR based phaser

This is a phaser, based on the thousands of effects that can be found on the internet and mainly on the post "The technology of phase shifters and flangers" of R.G.Keen., unifying all in one, with easy to find and cheap components.

No more to say, the scheme:

The LFO is borrowed from Culturejam's "Shot to the Moon" tremolo pedal.

1. The LEDs are red.
2. The LDRs are common 10K light and 1M dark.

Soon i will place the layout, all your contributions are welcome.
(I'm spanish, sorry by my eng)

[amptramp]

There should be a variable resistor set up as the speed control connected between IC3A pin 2 and IC3A pin 1 and C6 should go from IC3A pin 2 to ground in order to get this stage to be the LFO.  The 100K pot sets depth, not speed as shown.

The input impedance is 100K set by R2 in parallel with the 1 Meg anti-pop resistor R1 or around 91K total.  The design may be better served by a non-inverting buffer which would permit a higher input impedance.  The design as it stands is OK if you are driving it from a low-impedance device, but not if you are going directly from a guitar to the unit.  This means the output of the device would be inverted, but this is rarely a problem.

The depth control affects the bias on D2.  The current through D2 goes up on average as the control is moved clockwise (the direction of the arrow), but the amplitude of the change in current goes to half of what it is at the minimum setting.  Perhaps a pot in series with R23 is what you actually want.  It is not clear what the light source is for the LDR's.  Does D1 go to LDR1 and D2 to LDR2 or does D2 go to both and is D1 only an indicator lamp?

[Crontox102098]

There should be a variable resistor set up as the speed control connected between IC3A pin 2 and IC3A pin 1 and C6 should go from IC3A pin 2 to ground in order to get this stage to be the LFO.  The 100K pot sets depth, not speed as shown.

The input impedance is 100K set by R2 in parallel with the 1 Meg anti-pop resistor R1 or around 91K total.  The design may be better served by a non-inverting buffer which would permit a higher input impedance.  The design as it stands is OK if you are driving it from a low-impedance device, but not if you are going directly from a guitar to the unit.  This means the output of the device would be inverted, but this is rarely a problem.

The depth control affects the bias on D2.  The current through D2 goes up on average as the control is moved clockwise (the direction of the arrow), but the amplitude of the change in current goes to half of what it is at the minimum setting.  Perhaps a pot in series with R23 is what you actually want.  It is not clear what the light source is for the LDR's.  Does D1 go to LDR1 and D2 to LDR2 or does D2 go to both and is D1 only an indicator lamp?

I sould pay attention in the input impedance and do that you suggest... 2 LDRs give the light from D1.

[noisette]

The obsession to make things more tiny is really a nice direction. But you have yet to beat the Hollis/Easyvibe   (which is a phaser when built with repeating cap value/ technically even without).
http://www.hollis.co.uk/john/easyvibe.jpg

One thing that could improve that circuit is adding feedback. That would add nothing more than a voltage divider pot between the output of 2B and the -in of 1A.
Or maybe even just a 2 resistors and a switch, a tiny one

Btw. the R10/R11 connection has not been made by eagle.

[amptramp]

I sould pay attention in the input impedance and do that you suggest... 2 LDRs give the light from D1.

D1 is controlled directly from the buffer stage and the level control has no effect on it.  You existing speed control actually controls depth, but it is frequency dependent, so you might want to change it.  If D2 is only an indicator then your existing depth control only affects what you see, not what you hear.

[Crontox102098]

I sould pay attention in the input impedance and do that you suggest... 2 LDRs give the light from D1.

D1 is controlled directly from the buffer stage and the level control has no effect on it.  You existing speed control actually controls depth, but it is frequency dependent, so you might want to change it.  If D2 is only an indicator then your existing depth control only affects what you see, not what you hear.

Uhh  sorry, i didn't saw that... is D2 that gives light. D1 is only an frequency indicator.

[Kipper4]

Necro post.
I came cross this searching the forum for something else.
Did anyone ever build it and get it working please.

[mth5044]

The LFO needs work as stated. It's missing a 220k resistor between pin 2 and 5 of IC3 and some of the values are different from the Shoot the Moon LFO. Not sure if that was intentional. The phase part looks sort of like a Phase 45 with LDRs instead of transistors.

[Kipper4]

Yep Thanks Matt gottya.
Its high time I made a stand alone perf of a good LFO for breadboarding.
So as soon I can I'll throw it on the BB and report back.
Thanks for the help
Rich

[Kipper4]

After a few days pondering why my lfo isnt lfoing.
Note to self. Do not put a 47uf smoothing cap at the vbias node.
Its working, I now have a nice shoot the moon lfo ready for breadboarding.

[Kipper4]

Yep it works.
first experiment with a single ldr. Might need to keep the depth control down.
using 5mm bright yellow led and a bitsbox 10k lux 1M dark ldr.
Its kinda like   a tremolo more than a phaser. perhaps it needs a tweeking.
i'll try two ldrs next see if its any better.