Mini Commander triacs

Email Gunrunnerjohn, im sure he can give you the part numbers and links to Digikey.

Well, the largest parts on the MC-II are the four diodes, the only parts that appear to be the possible drivers are the two 8-pin parts.  I can't find any reference to the numbers or partial numbers there with a search, so I'm not entirely sure what they are.  Being IR parts, they're likely the drivers.  I don't know if they'd be triacs or FETs, can't find anything on them.  Given the size, I'd be thinking possibly FET parts as they wouldn't be dissipating as much power as triacs.  Pushing an amp or more through a triac of that size would probably get the sucker pretty hot.

Check ALLDATASHEET.COM "F7343".  It has the info your looking for.

As I suspected, they are FET's, I couldn't imagine them being triacs.  I wondered why only two packaages, that was answered in the datasheet.

Mouser and Digikey both have them in stock.

Thanks John - I was thinking of the Mini Commander HC/ACC, not the MC2.  How easy is it to implement variable control of AC with MOSFETs?  Is it the same notion of duty cycle as it is for a triac?

I poked and prodded one of my Mini Commander HCs and was able to pick out the HC triacs as T2322BG.  This raises two questions:

1) The older Mini Commander HC had one T2322B and one beefier triac in a TO-222-2 package for the higher current output. What was the change that permitted use of the smaller T2322B for the same applications? 

2) Is the T322B still a good choice for this kind of application, if we're sticking with triacs? The 2N607 series seems to have a lower on-state voltage and holding current, but I'm not familiar enough with triacs to know if those are good things.

Personally, I'd go for the FETs, they offer very smooth control and are easily driven using PWM from the uP.  FWIW, that's how I vary the smoke fan and the Rule-17 lighting on my Super-Chuffer.  The other bonus is they're very small and low power dissipation.  My only addition would probably be a TVS across the outputs for any spike control.

Professor Chaos posted:

1) The older Mini Commander HC had one T2322B and one beefier triac in a TO-222-2 package for the higher current output. What was the change that permitted use of the smaller T2322B for the same applications? 

AFAIK, there was no "change" that allowed higher current in the smaller package, any of the HC models had the TO-220 triac.  There doesn't appear to be any other changes, they just popped the larger triac into the same holes.

There used to be an option to handle motorized units with the same board that the MC-ACC is based on, so it would be kinda' cool if we could kill two birds with one stone.  Once you have the hardware, just drop in different software.

I will also say, certain motors didn't react well to the MC-ACC, but I never had an issue with the MC-II, another reason I lean to the FET's.

You're right John - I think the original HC had a single TO-220, and the HCv2 added the T2322B as a second HC output.

Can you point me to a FET circuit example?  I can find some mains examples on the web but if you have something for our voltages I'd be much obliged.

My circuit is simply single-ended and not isolated as it wasn't necessary for what I was doing.

There are tons of H-Bridge driver chips that are a one-stop shop, probably an easier way to accomplish the goal.

This one is worth a look, it has a simple interace and only $1.19 quantity one: TI DRV8837DSGR .  The one sticking point is 11 volts max motor voltage, but that's the idea.

Here's a typical H-Bridge circuit for driving a motor, clearly a lot more components.  I'd be researching the drivers.

I found one that should do the trick!  

The TI DRV8871DDAR has a wide operating range and will drive up to 3.6A (peak).  It should easily drive an amp or so and be loafing.

I'm sure with a little looking there are other options as well.

Back on the subject of triacs, can anyone provide a diagram of how to hook up a microcontroller like an Arduino to drive a triac, with phase control being the object?

I've got the zero cross detect working, but all the examples I of microcontroller phase find are using optocouplers and mains voltage. This application note seems to provide an example of a direct connection, but leaves out basic information like whether the gate is driven high or low to activate the triac, where the load should go, and whether there must be (or can be) any connection between the µC ground and the AC line.

Personally, I'd want the triac to be opto-coupled anyway. 

How come John?  It’s an extra component, and the Mini Commander ACC didn’t use it.

I guess I've just had bad luck connecting my logic directly to triacs.

Here's an ap note from TI about interfacing triacs, they have quite a bit of information that applies generally.  I suspect they have a lot more experience with TRIACs than I do.

Low Cost TRIAC Control With MPS430 16-Bit Microcontroller

I'm assuming since you're looking at the MC type of application you will need zero crossing detection to provide variable power, right?

Thanks John - any idea why the TI drive circuits (Figs. 2 & 8) have a 100 nF capacitor in series with the gate?  This note suggests a small series resistor.

The zero crossing was easy; just a series resistor (as described in this note).  100k in this case, about 0.2 mA which should be ok for the clamping diodes. I do have to adjust the timing of the control pulse a little bit because the clamped waveform is not symmetrical between the positive and negative half-cycles. 

The AP Note mentioned a large spike coming back through the gate, I suspect that's what they're doing there.