Johansen Engineering Steiner VCF RevB

Status - VCF working

Initial

Stage	Detail	Status
create material	sch/pcb	OK
	gerber	OK
production		OK
	produced	OK
	delivered	Delivered

Preliminary validation

Test	Detail	Status
Initial Inspection	VCO	OK - bottom looks empty w/o gnd fill
Initial Inspection	VCF	OK - bottom looks empty w/o gnd fill
		Very difficult to mount as footprints are getting over soldering points in many places
		BP in the bottom
		HP in the middle
		LP on top
Initial Inspection	VCF SMD	OK - bottom looks empty w/o gnd fill
Initial Technical Test	VCO	SINE has PCB error - and Sine pot has +12V to chassis
Initial Technical Test	VCF	One pot gets -12v on chassis
Initial Technical Test	VCF SMD
Initial Product Test	VCO	Nice -
Initial Product Test	VCF
		CV1 and CV2 works fine
		Q is doing something
		Uncertain if the freq pot is right
Initial Product Test	VCF SMD

Secondary validation

Test	Detail	Status
Product Test
Product Test
Quality
Quality
Long Term Product Test
Power Draw	VCO	+12 4mA -12
Power Draw	VCF	+12 8mA -12
Power Draw	VCF SMD	+12 ?mA -12

Errata

Errata - VCO

• Due to footprint one of the pots gets -12v on chassis

• Sine signal is shorted to GND

• Glide pot is reversed

Errata - VCF

• Due to footprint one of the pots gets -12v on chassis

• R127 - DNP (Do not populate)

• R119 swap with 220nF-1uF to ac couple input stage

• R126 swap with 1uF to ac couple input stage

Errata - VCF SMD

Issues and Notes

VCF

Very difficult to mount as footprints are getting over soldering points in many places

VCO

• Remove output pots
• Collect jacks in the bottom
• Fix errors (glide, POT, PCB errors, footprint tightened)
• Consider removing sine shaper

Pictures

Schematic

Layout

Inspiration

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Johansen Engineering Steiner VCF

Purpose

Test some of the original designs for inspiration and reference.

Status - Preliminary tests

Initial

Stage	Detail	Status
create material	sch/pcb	produced Rev A
	gerber	produced and uploaded RevA
production	ordered	OK
	produced	OK
	delivered	OK

Preliminary validation

Test	Detail	Status
Initial Inspection	THT VCF - Visual - Component Mounting	NOT OK
Initial Inspection	SMD VCF - Visual - Component Mounting	NOT OK
Initial Inspection	VCO - Visual - Component Mounting	OK
Initial Technical Test	THT VCF - Base operation	NOT OK
	Knobs	Freq working for LP - Q for HP/BP - CV trim - not ok
Initial Technical Test	SMD VCF	NOT TESTED
Initial Technical Test	VCO - Sine - Triangle - Square	OK
	Trimmers	OK
	Knobs	OK
Initial Product Test	VCO CV from LFO	OK
	VCO Vactrol CV from LFO	no real effect with CV coupling

Secondary validation

Test	Detail	Status
Product Test	VCF
Product Test	VCO	Works nicely - frequency is a bit high
Quality	VCF
Quality	VCO
Long Term Product Test	VCO	OpAmp gets hot - esp if no output is conn to the square
Power Draw	VCO	50-120mA depending on output...

Errata

Errata - THT VCF

• C111 reverse polarity
• R102 should go from +10v to connection between R103 and R106 - and +10v sould not go to Q102 base - Critical

Errata - SMD VCF

• R should go from +10v to connection between R and R - and +10v sould not go to Q base - Critical

Errata - VCO

• 470K values not correct for all resistors
• 0R values not correct - fixed in RevB
• Outputs should not be shorted to GND when not connected

Issues and Notes

VCF THT/SMD

• The filter needs adjustments and the feedback is not stable. a 56k from CV to base of Q102 helps a bit.
• Input circuit for CV needs rework
• Input series resistor and capacitor could be a good addon for the filter inputs
• Frequency adjust seems to work for LP only
• Q adjust is minor and seems to work on HP and a bit on BP

VCO

• Tweak values for better frequency range
• Op Amp can get hot
• Draws more power if nothing is inserted into the Square output?

Physical Construction

Features

SMD VCF Schematic

VCO Schematic

Inspirational sources:

Steiner VCF 1974 THT

Steiner VCF 1974 SMD

Same schematic - different components - half the size

VCO ICL 8083

Based on a Thomas Henry schematic

Details