Monday, August 21, 2017

Modular Sequencing: 01 - LFO Gate

A simple LFO can be a useful source for generating a gate signal.

A 40106 hex inverter is used in conjunction with a capacitor and a potentiometer to generate a low frequency square wave. The voltage level is divided in half for a 6V gate signal. The output connection is then protected using a diode and a resistor. An LED displays the output signal.

The supply of the modular case is used as a power source for the circuit. Only the 12V and ground connections are used. 12V can be used directly with the 40106. A 10 pin socket to 10 pin socket modular power cable can be used to wire the power supply bus of the circuit.

The potentiometer and the capacitor can be replaced with different values to change the frequency of the square wave. One 40106 hex inverter can be used to make up to 6 LFOs.

The ratio of the lower 10k resistor compared to the upper 10k resistor determines the output voltage in relation to the supply voltage. If a different supply is used or if a different gate voltage is desired, adjust the voltgae division accordingly.

For example, if the supply voltage is 12V and a gate output of 9V is desired, the upper resistor could be changed to approximately 3k and the lower resistor to approximately 9k, yielding a division of 3k / (3k + 9k).

The two 10k resistors can be omitted if using a 5V supply.