ULN2003A driving IRF540N mosfet

Like this

"Here's one I prepared earlier"

http://www.element14.com/community/groups/internet-of-things/blog/2014/08/05/drive-big-things-with-added-safety-opto-isolators

Regards

Peter

Trust you to have polished your crystal ball. 

I always cringe when expensive hardware is not protected ...

The advantage of the opto-couplers is they can be remote from the processor, and even duplicated.

Mark

I have read through Peter's post linked above.

Very wise indeed.  I think this is a good idea for this project.

Can you suggest a particular model of OPTO Isolator ?  I will need 14 outputs in total, so the more on a single chip the better!   I will probably buy them from Jaycar:  www.jaycar.com.au

On a side note:  What program do you use to draw up all your schematics?  I have tried a few but none of them seem as good as the schematics that are produced on this site and others.

I see he's using an unlicensed copy of Johnny Cad and added his own logo.....This is simply terrible!

Wasn't the optoisolator the preferred method last time this was raised BTW?

unlicensed copy of Johnny Cad

Yes but his isn;t the Johnny version.

Wallarug

I can't recommend any particular one, but you could try the 4 pin versions.

Jaycar only seem to have 6 pin single channel.

Since you are down under you could always try element14.co.au

This one is 16 pin 4 channel and most seems to have Ic = 50mA, and 300% transfer (ie 1mA LED gives 3mA Collector)

http://au.element14.com/vishay/k844p/opto-coupler/dp/1328383

Toshiba have some multi channel higher current but MUCH higher price.

Mark

Wasn't the optoisolator the preferred method last time this was raised BTW?

No.  This is the first time I have heard of a optoisolator.  In the last discussion no-one even suggested them, which is why I was a bit confused when they came up here.

Link to previous discussion:  http://www.element14.com/community/message/113013/l/arduino-and-transistors-question--re-school-musical-production#11301…

I will take a detailed look at everything that everyone has posted on this thread and consider what I might do.

>> I see he's using an unlicensed copy of Johnny Cad and added his own logo.....This is simply terrible!

I don't think any version of Johnny Cad is going to cut it for the project I have in mind.  Is there an more digital alternative to Johnny Cad?

Actually the opto-coupler did come up in reply #105

http://www.element14.com/community/message/114536/l/re-arduino-and-transistors-question--re-school-musical-production#114536

To be fair optoisolator and optocoupler are basically the same device.

Sometimes the 'isolator' can have a mechanical interrupter (ie mouse wheel, door switch, end stop) that breaks the link between the LED and detector.

You have obviously gotten to the point where your skills are being used more and more.

This is the opportunity to plan for the future and make the board/boards able to be multiversal.

If you make the board with an optocoupler and bring out both the Anode and Cathode along with the ability to change the series resistance, then it could be driven by almost anything you want.

Several could even be run in parallel, and at some distance from the controller, or switch bank or whatever.

I did this once with a Jackpot system controller which switched 24vAC and was perfect when one establishement wanted two signs linked together.

Mark

Optoisolator/optocouplers are are used to describe what is basically the same thing.  After a while people may use the wrong exact term but every one knows what they mean (fortunately) I'm sure this goes for many fields of knowledge.

If you go the E14 route I'm sure you can pic up some of the quad packages like this one here:

http://uk.farnell.com/toshiba/tlp620-4-gb/optocoupler-quad-5kv-transtr-o/dp/1225838

This is the UK one but I'm sure you can find the part in the .Au  E14or Farnell

For the cad package have you considered Eagle which has a free version for low complexity boards (this one should be OK).

Or go for completely opensource and go for Kicad

http://www.cadsoftusa.com/

http://www.kicad-pcb.org/display/KICAD/KiCad+EDA+Software+Suite

For faster response time you can use the Darlington output versions, this provides faster rise time on the outputs, these are what I used for the Electronic Referee project

For faster response time you can use the Darlington output versions, this provides faster rise time on the outputs, these are what I used for the Electronic Referee project