Juergen Haible Krautrockphaser in MOTM

Description for Original Haible pcb (and randomsource Version) but the BOM is correct too, there is only a difference in design and extra Stage output, extra resonance pot option

Modifications Page: (CV MOD)

Schematics:

jh_krautrock_phaser_sch.pdf

further buildinginfos:

http://www.dragonflyalley.com/constructionJHKrautrockPhaser.htm

building tip:

use sockets for the 33nF Film caps - see bugtrack info

use 50K REV LOG pot for osc periode and bridge wiper to left pin (rearview)

Bugtracking/Known Build Problems:

if your modulation pot doesn´t work, check your wiring at active/bypass switch and check that you have the Bridge at the OSC Periode Pins (see above) (its also shown in the schematics)

if your sound is have to many middle sound, try other capaciator values (original is 33nF) sometimes 47nf or 68nf sounds better.

Feedback - bridge Pin1-2 in every case on the Random Source PCB for the Feedback path

Feedback not working: don't use Modular Levels (5VPP) for audio input - otherwise FB isn't working as designed.

Bill of Materials (BOM)

Here's a list of components that I've used:

Krautrock Phaser BOM.

It only contains the components that are soldered to the board, no front panel components.
You'll want to have a nice "retro" looking lamp holder on th efront panel, too.
The incandescent lamp for the front panel is the same type as the two for illuminating the LDRs.
In Europe, E10 sockets are probably more common than elsewhere in the world. You can choose whatever socket you want - it just has to fit the lamp you're using. You can also simply solder the lamps to the PCBs with short, stiff wires, if you don't find a socket that fits into the PCB.
The lamps I'm using are 7V / 100mA types - spec'ed the same as in the original Compact A Phasing. If you cannot get these, you can try with 6.3V lamps of approximately the same power (0.7 Watt). In that case, you have to connect two 1N4002 diodes in series with these lamps. The PCB has the necessary pads and holes for this already, but I have not tested 6.3V lamps myself.

-> non standard homestock parts from BOM:

5W 120Ohm resistor axial (reichelt)

Relay: Finder 30.22.9 12 (reichelt)

1x 50K log pot (banzai)

3x 50k lin pot (banzai)

13 SMT 805/1206  100n capaciator (reichelt)

cmos CD4007 (reichelt)

12x ua741 or Lm741 (reichelt)

1x MC1458 - or LM1458 (reichelt)

(dont use TL072 ! )

Basic Connection/Controls (common to all options)

Modulation Knob

Feedback Knob

Oscillation Period Knob

Modulation Depth Knob

Bypass Momentary Switch

Mode Switch

Modulation Indicator

Bypass Pedal Jack

Rate Pedal Jack

Depth Pedal Jack

Input Jack

Output L/Stereo Jack

Output R/Mono Jack