Thread: Rework of the 5v to 24v relay driver

Originally Posted by Malibu

With Neil being approachable enough to put up an Electronics forum (thanks Neil!) I'm lucky enough to get first crack in the postings...
I don't have any new designs, so I've re-posted the schematic first put into CNC's for the 5 to 24 volt relay.
The original schematic had a comment that it needed back-EMF diodes (quite rightly so, too) so I've redrawn the circuit with the extra diodes, plus a reverse voltage diode on the 24V supply in. This latest version of the circuit is not tested, but the one in use at the moment is working spot on. (the picture is for version 1 of the schematic, no diodes)

Input voltage can easily changed by altering the value of the resistors to the opto's, as can the current output by changing the transistors. The values and componants I used in my prototype is what I had in my 'junk' box.

As mentioned in the first post, this will fit perfect to the C10 breakout board for CNC control, but can easily be adapted to suit any other low voltage isolation drivers for simple on-off control...

Enjoy

G'day Malibu.
Great to see this new forum - just what we needed, and now my other interest is covered here at WWF.
A quick suggestion - I would have put protection diodes across the transistors, from emitter to collector, to stop the emitter voltage skyrocketing on switch-off: -

Edit: I killed the suggestion above - I was half asleep - the emitter in a common collector circuit will have a negative spike on switch-off and not a positive one. (A common emitter circuit would have a positive spike on switch-off.)

Originally Posted by Humphrey9999

G'day Malibu.
Great to see this new forum - just what we needed, and now my other interest is covered here at WWF.

Edit: I killed the suggestion above - I was half asleep - the emitter in a common collector circuit will have a negative spike on switch-off and not a positive one. (A common emitter circuit would have a positive spike on switch-off.)

G'day Humphrey,
Hopefully, it will take off... I suspect there's more electronics tinkerers and people with an active interest out there than what's thought. I'm surprised an electronics forum hasn't been put up earlier.

In regard to your suggestion - As someone who's training in electronics is limited to being an avid reader of (the sadly demised) Electronics Australia as a kid, plus my fair share of popped transistors through many disasters, I'm more than all ears to any suggestions anyone has!
I don't know what the voltage for the 547's is, but for the initial circuit and relays I used, I considered the spike from drop-out to be negligible. As a generic design, I should have known better and considered all possibilities and added diodes. (I guess that's where this part of the forum will be a boon; people like yourself adding finishing touches and good ideas)
This circuit was really just a quick hash-up to get me going with the job I had on hand. I'll work on it a bit more and make it more presentable as a 'project'.

Mark 3 is on its way, once I get a few other things out of the way around the house (Cleaning the workshop for one!) and I'll re-post as a 'project' that may be handy for anyone that might have a use

Originally Posted by Malibu

G'day Humphrey,
Hopefully, it will take off... I suspect there's more electronics tinkerers and people with an active interest out there than what's thought. I'm surprised an electronics forum hasn't been put up earlier.

That's fixed now.

In regard to your suggestion - As someone who's training in electronics is limited to being an avid reader of (the sadly demised) Electronics Australia as a kid, plus my fair share of popped transistors through many disasters, I'm more than all ears to any suggestions anyone has!

Hobbyist electronics is pretty well dead in this country, unfortunately. (And elsewhere, I suspect.) A shame that they killed off EA, but at least Silicon Chip survives. I used to write small articles for both, many years ago.

I don't know what the voltage for the 547's is, but for the initial circuit and relays I used, I considered the spike from drop-out to be negligible. As a generic design, I should have known better and considered all possibilities and added diodes. (I guess that's where this part of the forum will be a boon; people like yourself adding finishing touches and good ideas)
This circuit was really just a quick hash-up to get me going with the job I had on hand. I'll work on it a bit more and make it more presentable as a 'project'.

A 547 can handle 45VDC between the emitter and collector - fine for this circuit. Collector current is 100mA max. (You probably already know that.)

Originally Posted by Humphrey9999

Hobbyist electronics is pretty well dead in this country, unfortunately.

I'll agree in terms of scratch-built hardware design, particularly analog, especially since SMT and BGA devices make it almost impossible to design anything more complicated than a linear power supply or simple audio amp. However, many people are still building (assembling) things, you only need to look at the variety of kits and modules available on ebay - I regularly buy pre-built modules from China - there is simply no way I can design and build it myself for the price.

I've been a professional electronic engineer for nearly 30 years, and the market for any sort of hardware design these days is very small. But the demand for embedded firmware engineers is strong. I've found most companies these days are unwilling to design hardware in-house. They'd rather buy a pre-built board and develop their own custom firmware. In-house design is just too risky, too expensive, and takes too long.

Originally Posted by Humphrey9999

I used to write small articles for both, many years ago.

Me too, but it's probably 10 years or more since I've even looked at a paper magazine.

Originally Posted by sjm

I'll agree in terms of scratch-built hardware design, particularly analog, especially since SMT and BGA devices make it almost impossible to design anything more complicated than a linear power supply or simple audio amp. However, many people are still building (assembling) things, you only need to look at the variety of kits and modules available on ebay - I regularly buy pre-built modules from China - there is simply no way I can design and build it myself for the price.

Exactly my point - bought some RF transceiver modules a little while ago, 1km+ range, about $20 or $30 each and only about 25mm x 15mm. Can't compete with that in DIY design.

When I said hobbyist electronics is dead, I did mean design rather than assembly. I stopped too, when everything went SMT. My eyes aren't up to it. 2.54mm pin spacings are hard enough for me these days.

I've been a professional electronic engineer for nearly 30 years, and the market for any sort of hardware design these days is very small. But the demand for embedded firmware engineers is strong. I've found most companies these days are unwilling to design hardware in-house. They'd rather buy a pre-built board and develop their own custom firmware. In-house design is just too risky, too expensive, and takes too long.

Most of my stuff was PIC-based, doing exactly this sort of thing - motor controllers/drivers etc.

Me too, but it's probably 10 years or more since I've even looked at a paper magazine.

About 13 for me, and over a year since I've done any electronics at all - just woodwork now.

Seems like we all have a real common interest here !
I did electronics/communication for many years, now on demand only...

The other day I went to a jay..r store for some parts (a friend wanted some veroboard assemblies made up)
and people looked at me like I was building nuclear detonators or something !!!

In hindsight, nuclear dets. would have paid better !!!

I also haven't read a paper mag for years........ 15++ ??

So if anyone has questions, feel free to ask..................

Geoff

Lots of good points made, some I agree with, some I don't...
Isn't, though, the point of these forums, promotion and help in being a 'do it your selfer'? I could have bought a driver board from overseas, delivered for a fraction of what it cost for this one in time and money; probably more professional looking and done with the latest in sub-miniature technological components. I could have also bought the machine it went on for a fraction of what it cost me to build one, but I don't see the point in being a 'handy' person, if I don't get my hands on things. Just my opinion

Anyway, here's the latest version... Diodes are in, schematic is up to date and a modified circuit board to suit the new design has been made by isolation routing (a far cry from the old way I used to do prototypes - but that's another story!). The board is populated and already in the machine, working a treat
So far, I've only needed one channel to control the spindle and coolant pump, but there's 3 spare outs that I have plans for later down the track. Maybe for vacuum control and a solenoid for the lubrication.

I'm pretty proud of it even though it's only a simple circuit. Maybe I should say - proudly designed in Australia, made in Australia, built in Australia, by an Australian on Australia Day...
hmmmm.. and no input from China............

Originally Posted by Malibu

Lots of good points made, some I agree with, some I don't...
Isn't, though, the point of these forums, promotion and help in being a 'do it your selfer'? I could have bought a driver board from overseas, delivered for a fraction of what it cost for this one in time and money; probably more professional looking and done with the latest in sub-miniature technological components. I could have also bought the machine it went on for a fraction of what it cost me to build one, but I don't see the point in being a 'handy' person, if I don't get my hands on things. Just my opinion

Anyway, here's the latest version... Diodes are in, schematic is up to date and a modified circuit board to suit the new design has been made by isolation routing (a far cry from the old way I used to do prototypes - but that's another story!). The board is populated and already in the machine, working a treat
So far, I've only needed one channel to control the spindle and coolant pump, but there's 3 spare outs that I have plans for later down the track. Maybe for vacuum control and a solenoid for the lubrication.

I'm pretty proud of it even though it's only a simple circuit. Maybe I should say - proudly designed in Australia, made in Australia, built in Australia, by an Australian on Australia Day...
hmmmm.. and no input from China............

Looks good. Nice job on the board.

Originally Posted by gyropilot

The other day I went to a jay..r store for some parts (a friend wanted some veroboard assemblies made up)
and people looked at me like I was building nuclear detonators or something !!!

In hindsight, nuclear dets. would have paid better !!!

Ha, yeah. I bought a stack of MOSFETS and high current motor driver ICs from Digikey or Mouser in the US a couple of years ago and had to jump through a series of hoops just to have them sent out of the US, for national security reasons. (Might be a terrorist.)

It may even be that some of you can make a little on the side from this board too.

For instance, I have a Huanyang imverter that only works on the input side but not on the output. They seem to be a basically simple design (mostly surface mounted resistors and stuff like that) but I have no idea how they work. Does anyone feel competent to repair it for me at a price that is miserly? Preferrably somebody in the Brisbane southside area but I can post it too.

It may even be that some of you can make a little on the side from this board too.

That's probably a good idea Bob. It seems pretty hard to get electronics stuff fixed now because everything is a disposable design. Maybe it will make a good sub-forum of 'Request For Repair' or something.

For instance, I have a Huanyang imverter that only works on the input side but not on the output. They seem to be a basically simple design (mostly surface mounted resistors and stuff like that) but I have no idea how they work. Does anyone feel competent to repair it for me at a price that is miserly?

Unfortunately, it's not me. I'm not that up with electronics to be able to fix something like that.

Originally Posted by Bob Willson

It may even be that some of you can make a little on the side from this board too.

For instance, I have a Huanyang imverter that only works on the input side but not on the output. They seem to be a basically simple design (mostly surface mounted resistors and stuff like that) but I have no idea how they work. Does anyone feel competent to repair it for me at a price that is miserly? Preferrably somebody in the Brisbane southside area but I can post it too.

Maybe a picture of the unit. A bit more info, too, ie. Functions, number and type of IO etc. Model number might help. (I'm not putting my hand up - I can't see things that small any more. The manual looks like a pretty hefty read, too.)

The design won't be that simple. A microcontroller, motor driver(s) and so on. There's quite a bit going on in these inverters. A quick search tells me that the output IGBTs often fail, possibly a starting point is to check resistances across the IGBT pins. (They shouldn't be shorted.)

Ideally, someone that's familiar with both these units and electronic repair is needed. A separate thread would be a good idea.

The 1GBTs are power transistors aren't they? Does the part have to be removed to test for shorts, because if not, then I can do that fairly easily?

I can't see things that small any more.

I hear ya!
I can hardly see the black cubes, let alone the value on them..............

A separate thread would be a good idea.

Might get a bit more attention that way