AM8220 LFO

8 HP | AM8220 LFO & NOISE | User Manual (PDF) | ModularGrid | You Tube

OVERVIEW This module is an accurate and expanded replica of the LFO in the Roland SH-101 analog mono synth which was released in 1982. 

DESCRIPTON The LFO is based on dual Op Amp that generates both triangle and square waves from 0.35Hz to 30Hz. The frequency is controlled by a LED slide potentiometer (the LED flashes at the LFO rate). A range switch has been added to enable the LFO to run at lower and higher frequencies.

The triangle wave is converted to a sine wave and is available as a seperate audio output that is switched on/off by the front panel MOD switch and/or an external gate input. The volume of this sine wave is adjusted iwth the S-MOD slider, the LED illuminates when the sine wave is active. 

The LFO can be locked into an external clock so that the waveforms start at the end of the gate signal. A front panel switch controls whether the LFO is free running or uses the external lock.

The original LFO uses a digitally generated Random signal which we have replaced with a traditional Sample & Hold circuit (from the SH-02), to create a random stepped waveform from sampling the onboard noise signal with the sqaure waveform.

A 4-way rotary switch selects which waveform appears on the main audio output;

• Triangle
• Sqaure
• Noise
• Random
•  

The onboard noise generator creates two outputs; a traditional white noise and a filtered noise for modulation. The noise has a dedicated output and a slide pot for adjusting the level. The modulation noise is selected from the waveform switch and appears on the main output if selected.

There are five 3.5 mm jack sockets on the front panel:

• CLOCK - external clock source
• GATE - traditional +5V gate signal 
• SINE - sine wave output
• OUTPUT - main LFO output
• NOISE - white/pink noise output
•  

The module comes with a set of M3 mounting screws and washers, and a standard Doepfer power cable.

PRODUCT STATUS: IN DEVELOPMENT