Monthly Archives: March 2018

VCA LN

Posted on by
VCA LN: populated PCB

VCA LN: populated PCB

A well known way to reduce noise in VCA is using the VCA’s in parallel. Here is my approach. A LM13700 used in parallel reduces the noise floor around 3dB.
Specs and features
• VCA with reduced noise floor
• Runs on +/-15V and +/-12V (with some resistors changed)

The documentation for download can be found in my website.

VCA LN: Schematic 01

VCA LN: Schematic 01

Nothing special here. Just two plain forward designed VCA with LM13700. With the signals added together.

VCA LN: Schematic 02

VCA LN: Schematic 02

Standard circuitry for Iabc and level control.

Divide and add

Posted on by
Divide and add front

Divide and add front

An interesting module to add more color to your sounds. The input signal triggers the 4024 binary counter whenever the signal crosses zero. Therefore you can use nearly any input signal not only squares. The outputs of the 4024 is are added together in two ways. One weighted the other with equal values. The weighted output gives you a more triangle shaped output. You can add lots of harmonics in widely adjustable different combinations.

Specs and features
• Divides nearly any signal
• Weighted and unweighted added output signal
• Add widely adjustable harmonics to you signal
• Runs on +/-15V and +/-12V

The documentation for download can be found in my website.

Divide and add: schematic

Divide and add: schematic

On every zero crossing the input signal triggers the binary counter 4024. The outputs of the counter are adjustable added together weighted and unweighted and the two signals are brought out.

Divide and add: populated PCB

Divide and add: populated PCB

Divide and add: back view

Divide and add: back view

Sequential Switch

Posted on by
Sequential Switch: Front view

Sequential Switch: Front view

This Module is build around the counter 4017. It provides you with with 8 bidirectional toggle switches. The active switch is signaled with a LED. All switches are brought out to the front panel, so you can patch this module with maximum flexibility. Audio signals are switched as well as control voltages. This module is clocked external and can be clocked with high frequencies. Way above the audio range if needed. You can select the stepped sequence length between 2..8 steps with a rotary switch. The reset input is brought out as well.
Specs and features
• Sequential switch with 2..8 steps
• Bidirectional toggle switches
• Audio and control voltages switchable
• External clock way above audio range
• Runs on +/-15V and +/-12V

The documentation for download can be found in my website.

Sequential Switch: Schematic

Sequential Switch: Schematic

The 4017 is clocked through the clock input with IC5C and IC5D. RS1 selects the sequence length. The DG419 toggle switches are successive toggled with the every active step of the 4017. The LED signals the active step.

Sequential Switch: Populated PCB

Sequential Switch: Populated PCB

Sequential Switch: Back view

Sequential Switch: Back view