robotmaker
I design alot of circuils been electronic engineer and was look at are using using switching transistors to turn on lights ,relays and more
Transistors are mostly old school design ,before mosfets came out,if you look at the h-bridges now that use mostfets instead of transisors
For a few reasons one is low RDS on ,with meens they can handle higher wattage and not get hot using transistors ,plus less voltage
The most common is n-channel and have 3 pins ,GATE witch goes to digital output with a current drive resistor then SOURCE witch is the load and DRAIN is ground
Now for protection for mosfets most have a diode that protect it from EMF or inductive kickback
MOST i see use diode on transistors from collector to emitter ,NOT a good idea manly it does suppress or stop the inductive kickback and if using a microprocessor or circuits with will get resets and more induce in th system
so where the diode goes is always across the coil with cathode (black line ) to postive and NO inductive kickback
DIODES are only needed for inductive loads ,motors and relays or coils
Not for resistance loads ,lights or heaters ,leds will put up a simple circuit
second part will be how to control AC products,RELAYS are also not good slow switching and as noises on the contacts that does resets but wull give info on how to fix them
HOPE this is easy to understand if not just ask a question
Last one is a circuit like RICH is using with correct place to put the diode.
Doesnt meen that where RICH has the diode wont work it will protect only the transistor.
But like all links say is called a flyback diode fior inductive kickbacks ,with diode across the coil no kickbacks,but on the transistor still will have it,it doesnt block the inductive kickback.
Pretty easy to see why.
TROY see any bad grammar on this post.
Don't tempt people to pull you up on your bad grammar by a question that doesn't end with a question mark...
Removed sarcastic correction - I do not wish to rock the boat further.
As Troy said, when posting a tutorial ensure it is clear, easy to read and as free from spelling mistakes as possible. Spelling tutorial incorrectly in the title isn't a good sign of what's to follow... And writing fast, or not liking to write is not an excuse, if that is the case then don't do it. If you had flagged up this method in my switching transistor tutorial I would have looked in to it and given the option for using Darlington transistors or Mosfets, the circuit is practically the same anyway.
It is not an attack on you so please refrain from getting defensive or taking offence. You must understand that a lot of people who read these posts may not have the same knowledge as you and they may not be able to understand what you are posting. Minor spelling mistakes and punctuation errors are neither here nor there, they can be overlooked but if it just doesn't make sense or isn't clear enough then people will struggle.
I'm sorry you missed the point about perception. You aren't being graded. That isn't the case. People are trying to understand you. It's pretty important when writing about technical things to a varying audience of technical experience. True or false? We do want to be helpful to the entire EZB community don't we? It's not about misspelling "meens" or using "witch" instead of which. Those thing are easily overlooked. Most times it's the missing word or part of a sentence that is confusing even before getting to a technical part. For the record, English was my worst subject in high school. I also haven't trained formally in component level electronics in 23 years but I do a bit of signal flow troubleshooting for all of that time. I will leave it at that. I'm trying to be helpful to you Fred. It's clear that you are taking offense even when you say you aren't so I will stop helping. Hopefully someone else will explain it better as I seem to have clearly failed.
TROY i understand what you are trying to do,but this post is not about bad grammar ,same with RICH trying to help me .
We need to stick to what this post it about adding the the comments even if you are trying to help makes me look bad
Comments like that should be off line or in a email ,then it doesnt make a person look bad
WHAT happen is you are in my place ,and you was the engineer and had bad grammar and you havent dint any writing in a long time and i said the comments to you
SOME say that the mosfet is not better then darlington how do the know that.
DATASHEETS and links can always show the proof,on using darlingtons they are used alot and have about the same info on the internet at mosfets and well known.
BUT doesnt make them better
IN about 2weeks when i get back can make some tests to show how its a better device but really is not needed,all you need is basic math and resistance of the dievices under test
Almost if not everyone never really use mosfets that much,i been using them for a very long time and used darlington transistors too
great example is H-BRIDGE before they used darlington transistors to turn on and off a motor load and now every design now uses a mosfet ,why ?
BACK to the tutorial what this is mainly about
I ordered 25 mosfets at less then $1 each and with 1 (1k)resistor whole circuit can be made for about $1
MOSFET has a built-in diode ,and alot smaller with higher wattage rating then TIP120 darlington.
So you save space,higher current (wattage ) and lower cost
And when i get back in 9 days will make a few boards and post them.
Hooking it up is the same as using a TIP120 DARLINGTON TRANSISTOR
As already explained and covered in the updated information (from a couple of days ago) on the TIP120/122 tutorial under additional information in post #1 of page 1.
This not about USING TIP120 its about using a MOSFET JUST another idea thats a little cheaper and handles a bigger load
Second i see you took credit for the mosfet by adding to your tutorial.
Again, perhaps a little clearer so you don't miss it this time. Using a Mosfet is included in the TIP120/TIP122 Tutorial
Information about the mosfet and where it fits in to the circuit has been added to the original post under additional information.