GRBL PWM Inverter Circuit

Here is another quick circuit – this time a GRBL PWM inverter circuit showing how to invert a PWM circuit with only three components. This works great to invert the PWM signal out of GRBL to driver a laser.

PWM Inverter Circuit

PWM Inverter Circuit

As a use example, PWM_In would come from the Spindle Speed output of a GRBLDuino CNC controller and be inverted on PWM`_Out to drive a laser with inverted logic requirements.

GRBL Relay Driver Circuit

Here is a quick relay driver circuit showing how to drive a relay from a microcontroller – specifically, one of my GRBLDuino products.


Microcontroller Relay Driver Circuit

Microcontroller Relay Driver Circuit


The circuit as shown is for a spindle control application but the circuit remains the same for any other use. 5V and GND are self explanatory. SPINEN is the signal coming out of the microcontroller and typically 0v DC or 5v DC. Microcontoller outputs can only switch a few mA before damage occurs, but this circuit allows the transistor Q1 to take the load and switch as much as it is rated.

To create a spindle control relay on GRBLDuino products,┬áSPINEN connects to the Sp EN terminal block (the side labeled +). GND is connected to the other side of this same terminal block. 5V must be connected to a 5v source – the simplest way is to use a wire with a Dupont plug to connect to the high side of the Lim. H/L header.

Here are more GRBLDuino posts!

Market Monday: Bolt Depot

Here is a new feature for the site: Market Monday. Each Monday I will share a supplier of some sort that may be useful to someone. They will be quite varied and all will be useful in some way.

First up is Bolt Depot. They have nearly every kind of hardware imaginable – wood screws, metal screws, hex bolts, carriage bolts, lag bolts, washers, eye bolts, J bolts, U bolts, etc. Next time you need some hardware, check them out.