nanoDLP

delaney

Member

Registered: 2018-04-13

Posts: 7

Understanding the Schematic

As a software engineer I'm new to hardware.  Understand most of the except...

E3  What is this part of the circuit doing?
D3  Is the servo / pwm for DLP?  I'm doing an LCD based, is this not needed.  Can I use for a stanard PWM fan?

Thanks!

Last edited by delaney (2018-04-20 23:30:13)

bigfilsing

Member

Registered: 2016-11-20

Posts: 306

Re: Understanding the Schematic

E3 shows 2 circuits. One protects the 5 volt supply rail from over voltage with some filtering and the other filters/ suppresses  the stepper motor supply voltage. Both are needed/ advisable hence them being included.
The PWM (servo) is for when a shutter is used ( typically on a projector) in my case I use it to drive my UV LEDs.
Good luck

delaney

Member

Registered: 2018-04-13

Posts: 7

Re: Understanding the Schematic

Thanks fro the quick response!  The one attached to the stepper motor made sense (included in the Pololu docs). 

Are the recommended BOM/spec for the other components? 
From the diagram it appears to  be a polarized and non polarized set of capacitors?
The diode is suppose to be rated for 5.1v but at what impedence / amperage?
Is there a name for that dual capicator + diode circuit so I can read more about it?

bigfilsing

Member

Registered: 2016-11-20

Posts: 306

Re: Understanding the Schematic

A lot of this can be found in the ramps 1.4 documentation.
The diode is actually a 5.1 volt zenner diode . It clips spikes or surges over 5.1 volts

It might be worth reading up on noise suppression and decoupling capacitor circuits.
I'm no expert but have figured a few things out over the years.
Good luck

delaney

Member

Registered: 2018-04-13

Posts: 7

Re: Understanding the Schematic

Now I'm more confused.  The diodes in the Ramps 1.4 bom are  N4004  but you are saying it more like these?   I'm I just blind looking for the BOM for the nanodlp pcb?

bigfilsing

Member

Registered: 2016-11-20

Posts: 306

Re: Understanding the Schematic

apologies for the confusion re the Ramps 1.4   These are just basic FDM printers expansion boards for Arduino Mega's  Many DLP users use them because they are cheap and have all the hardware need to drive a stepper motor and read an endstop & control a PWM out put.

The diode you talk about isnt a diode its a zenner diode . Just read up on the differences

delaney

Member

Registered: 2018-04-13

Posts: 7

Re: Understanding the Schematic

No problem, just all new to me.  Was planning on going the direct method.  Dealt with Ramps for FDM.  I guess my question still stands, what's the BOM for the direct method/pcb?  Also is the decoupling capacitor circuit necessary if I'm already using a switching power supply for the 5v?

Last edited by delaney (2018-04-20 19:37:20)