Döpfer A110-1 - Standard VCO

Provides VCO, Sawtooth, Sine, Square, Triangle, PWM, FM

A voltage controlled oscillator with a frequency range of about eight octaves (ca. 15Hz ... 8kHz). It can produce four waveforms simultaneously: rectangle, sawtooth, triangle, and sine wave. The output levels are typically 8Vpp for saw and rectangle, and 10Vpp for triangle and sine.

10 HP (51 mm), 90 mA @ +12V, 20 mA @ -12V, 0 mA @ +5V

Made by Döpfer.

Front panel

SYNC     Range
CV1      Tune
CV2      CV2
Saw  Sqr  Tri  Sin

Labels of switch positions and rotary detents

Range (rotary switch, clockwise)
0, 1, 2, 3, 4, 5, 6, 7, 8, 9


The frequency or pitch of the VCO is determined by the position of the octave (Range) switch and tuning (Tune) knob, and by the voltage present at the CV inputs. Footage (the octave of the fundamental) is set by the Range control in five steps, and Fine tuning controlled by the Tune knob. The tune knob range is about +/- 1/2 octave.

Pulse width of the square wave can be controlled via a knob (PW) and via the voltage present at the PW-CV1 (without attenuatior) and PW-CV2 (with attenuator) input.


The core is a sawtooth oscillator. The other waveforms are derived from the sawtooth by internal waveform converters. As the sawtooth reset (i.e. the back-to-zero slope) is not infinite fast but takes a little bit of time the derived waveforms triangle and sine are not perfect! At the top of the waveform they have a small glitch or notch that is caused by the sawtooth reset and cannot be eliminated by the waveform converters. The sine is derived from the triangle by a simple diode-based converter and the sine shape is not perfect (only a rounded triangle).

External links

See the homepage for more details.

Schneiders Laden has a page about this module.