noise from MOSFET?

[SolarTrap]

Hello all,

I want to replace a slide switch with a software controllable MOSFET and found this example (see drawing). I set it up on a breadboard and it works really nice with the ATtiny.

Now I want to use this for my existing circuit to basically replace the slide switch in the read circle and switch GND instead of V+ (see attachment). my circuit is working with audio in via a mic to drive 15x WS1812 LEDs to do some sound driven animation. As soon as the MOSFET (2N7000) is inserted in line between battery and GND I am getting crazy noise on the audio signal.
I am not even adding the rest of the components of the 'low side power switch', just the 2N7000 between battery(S) and GND(D) connected to V+(G)

Any suggestion why and how to fix this?

Thanks,
Markus

 

[3DDave]

At first glance this is using the 2N7000 to complete the circuit that powers the ATtiny and is controlled by the ATtiny. The 2N7000 is listed as limited to 200 mA; each WS1812b can require 60mA, so that looks like a problem.

Redraw the schematic exactly as you have it with the 2N7000 and other components and with the WS1812b LEDs connected. Also, what sort of microphone is being used. We can guess electret type, but it's best to be sure.

 

[SolarTrap]

Yes, the 200mA might be tight but I am running the LEDs on 6% power - that should be ok. There was a typo: LEDs are of type WS2812, also the mic is electret.
here is the updated schema. The GND is the Battery neg pole. I am not showing the LEDs which are also using switchGND:

 

[analogkid2digitalman]

Been over 30 years since I've worked with MOSFETS, but one circuit I devised had hi frequency oscillation on the output, adding a series gate resistor of a few hundred ohms squelched it.

-AK2DM