What is a snubber diode?

P

phils2um

Phil S
11 Sep 2015
330
114
Ann Arbor, Michigan
This question is directed to Greg but I think the answer may be of general interest. I've read you mention snubber diodes many times. In laymans terms, how does it work and how is it wired into a circuit? Thanks to any who reply.
 
John S

John S

Registered
5 Nov 2017
667
133
Exeter, Devon, UK
Or also known as, kickback diode, commutation diode, freewheeling diode, suppression diode, clamp diode, or catch diode.

Connected, across and as close to an inductive load (between the POS & NEG input supply voltage, silver (or black) band on diode towards the POS side) to eliminate flyback, which is the sudden voltage spike* seen across an inductive load (relay, motor, solenoid, read that as anything with a coil winding) when its supply current is reduced, interrupted, or stopped.

*Voltage spike, if left to it's own devices, can, will, would destroy any electronic component device etc, in the vicinity and nearby surrounding area, bit like having a cattle prod inserted where the sun don't shine!


132492_d109aaa0c890b7b67950b316dd8f0b58.png


Generalising and overview....for types of diodes that can used as "snubber diodes" within our sphere of the hobby.

Signal diode 1N41xx, used for low mA rated applications, HK-19F relay family for instance.

Rectifier diode 1N40xx used to convert AC voltage to DC voltage, DCC usage to covert the Signal/Voltage to DC.
In Analogue, regardless of controller direction, Positive will always be in the same consistent direction.
All round most common general purpose snubber diode, see below, Schottky for alternative.

Schottky diode 1N58xx lower forward voltage drop than a conventional 1N40xx and a very fast switching action.
Best used for heavy inductive loads (Amp's), motors and solenoids for example.
 
Last edited:
Rhinochugger

Rhinochugger

Retired Oik
27 Oct 2009
25,259
554
North West Norfolk
The sort of thing that was referred to as TV interference suppression in my youth ? :nerd::nerd:
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
23,485
491
Tamworth, Staffs.
The sort of thing that was referred to as TV interference suppression in my youth ? :nerd::nerd:
Not really...
That was normally a capacitor.

Think how 'old-school' car ignition systems generated a spark for the ignition.. Sudden collapse of field in the coil caused the spike used to create the spark. :nerd:
 
Rhinochugger

Rhinochugger

Retired Oik
27 Oct 2009
25,259
554
North West Norfolk
Not really...
That was normally a capacitor.

Think how 'old-school' car ignition systems generated a spark for the ignition.. Sudden collapse of field in the coil caused the spike used to create the spark. :nerd:
Ah, never really understood how a coil worked - just knew not to hold the end of the lead. Life was simpler then - if it didn't spark, you changed the points, if that didn't work, you changed the coil :D:D:D
 
Hutch

Hutch

G Gauge, Raising Peaches, Apricots
1 Feb 2012
371
7
Southwest Oklahoma, USA
Occasionally referred to as a damper diode by us Luddites.
---Hutch
 
P

phils2um

Phil S
11 Sep 2015
330
114
Ann Arbor, Michigan
Thanks John, for your very clear feedback (on how the diode is used to suppress undesirable voltage feedback!)