Phase Shifter2


Blue #6


Big LED and CdS Cell
I've got a feelings.
Whichever, an error between each of photo coupler comes out. Experiments of my friend shows us that though there is errors, I can get the great sounds. But it's just a trial. the shape of curve is almost same. So triming brightness of LED will change the rate and it make them same. Or big error is at high value areas, so putting pots with parallel make errors small. But each plan needs pot for each stage. If you build 6stage then you need 6 pots. Can we tune them ?
One day, a menber of Japanese local bbs at Abe's site introduce this page.
It lools like Cds Cells are dancing around campfire. This method allow as to trim thier distance from LED it means we can trim resistance each of them.
I want use big LED that I saw the local electrical shop. So I buy it.
I use NPN/PNP matched pair anti log method based on ARP style. I use no match one and don't use TC. But it works fine. there already is so big drift in CdS Cell. so it's enough for this circuits, I think.


So beautiful bule LED light
I use 2 LEDs. One drive CdS Cell and the other is monitor. I cover the LED and CdS Cell by cap to prevent getting affect of anbient light.
I build them and take a picture and I turn it on, then LED was burn. That's the end. I mistake to put NPN and PNP. There is no stock for another Big LED. So I put the blue high brightness LED.
The raw data at the previous page is gotten from this schematics. and it Input voltage vs. resistance.

it's so bright. And there is no matter about the sensivity about the color. it's too bright.I move CdS Cell many times but I cant get matching with them.

At last I know. What ever do about this, We can't get matching from them

Buiding a phase shifter, at last


Camp Fire style prototype #1
It's so hard to get matchings . And their linearity is so poor. there is no need to do something carefully. And I got the infomation about commercial phase shifter (BOSS's RPH-10 phaser) which has 12 stage. it's consist from modulated 8 stages and fixed several stages. No modulation is OK for the phase shifters ? It hit me so hard. So I change the basic design. I throw away their linearity and I get the dynamic range of modulation. The charm of CdS Cell is easy to use and low noise. not their lenarity or speeds.

The core of phase shifter is the value of resistor and capacitor at the single shifter. CdS Cell is dynamic resister and capaciter is fixed.
It's same as RC filter so if resister is high then value of capacitor will go down.And small capaciter is also small and it's ok for reduce the size of PCB. I love small one.

The cap made from paper board. I paint it black its inside
I had been wondering how to determin the value of capacity. if resistor of CdS Cell is low enough, then we can use small value for capacitor. And this make whole size of this PCB or something. At last, I get this methods that the most high value which we can use for CdS Cell will determin the value of capacity. this will cover the lowest frequency. and most high frequency will be determined by the brightness or color of the LED.
I use 6 stages .And I use my CdS Cell as under 50K. So 0.022uF will determin the loest frequency
I had so many experiments but if you try re-experiments this, you should have to know the highest value of CdS Cell in usual use. It will lead you to the value of capacitor in most few steps. And next get bright LEDs.

schematics consists phase shift stage and input mixer for feed back and out put mixer for mix the orginal sound and shifted one. and if you add them it's going to be twice levels. so input mixer had 1/2 atteneutor. this will make output level same as input.


Result

I use these software for windows it's free to use but great!

We can get white noise from "WaveGen" and I put it to my phase shifter and I back the output to the input of windows machine. My sound board is coming with the mother board. it's not bad but not so good. this result includes the frequency responce of my build in sound systems.

Orenge LED frequency responce
Sounds under -80db or so is just noise that we can hear as hiss. In usual audio aplication, -80db or -90db means no sounds. Red and blue line means that frequency responce that give 0V and 15V to the CV input.we can the the 3 dips just same as simulator in blue line. red line means too low to use this in audio. we can see the highest dip in 110Hz or so.
I feel that I need more lightness! Big LED is provies light all CdS cell, but it's not enough to drive them so low resistance. The difference between green one and orange one are so small. So I use high bright red LED.


Hi bright Red LED frequency responce
As same as the Big LED, red line means 0V, blue means 15V. Low area is almost same as big one. both LED had no light in 0V. this is most lowest responce for this. if highset responce make you satisfiy then add some CV to bring lowest responce whitch you need.
Self tuning is the most big charm point for D.I.Y. but, I know that we don't know what's the best setting is.
at first, you sould better to try the center dip to 1kHz or so. It's good start point for you. In my experiments, the voltage brings it to 1k is 7.85V in case of big LED and 4.79V for High bright red LED.


White light LED. I use NSPW500BS for this experients
Here comes the hero. "Mirror, mirror, what's the best in the world" , "Yes, It's snow white". Everybody said so ,I think. white have every light. so it drive CdS Cell so well. I love it!

another LED can't light when CV input is 0V.But bule and white LED can light in so small current. and it rise the resistance of CdS Cell. So we don't need inital tune pot for CV inputs. We can use 0-15V in full range. the voltage brings cf to 1k is 1.92. Just high area is good to use, I think.

You don't have to put on the red light ( Police/Roxane )


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"Phase Shifter 2 " Copyright 2003, Motohiko Takeda, Crow Hill Laboratory
Motohiko Takeda Mail:takeda@aleph.co.jp