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Projecttitel:  Fonik VCO 555 Thomas Henry


Startdate: 2012

Duedate: 09/2014

Manufacture link:



in the original schematic of the VCO frmo thomas henry we three times a resistor R26, whereas R25 is missing completely.
so here are the values corresponding to the PCB labeling that are not covered correctly by the schematic/parts list:
R25 - 300k
R26 - 39k
R55 - 5.6k

when powering from 12V:

R13 = 2k 
R27 = 22k 
R33 = 137k 

3) when you have a hard time finding a precision trimmer wit 25k, just use 50k. does the job as well. 4) C4 is the timing cap. use a nice C0G/NP0 or a mica for better stability.





  File Modified
JPEG File VCO555-schematic.JPG Aug 27, 2013 by LED-man
JPEG File VCO555-Partlist.JPG Aug 27, 2013 by LED-man
Text File info.txt Aug 27, 2013 by LED-man
GIF File 555-VCO_layout.gif Aug 27, 2013 by LED-man
GIF File 555VCO_FP_sketch.gif Aug 27, 2013 by LED-man
File vco-TH555.fpd 5u conversion for schaeffer panel- untested Sep 11, 2014 by LED-man