7 replies to this topic

[nevess]

Hi, 

 

I the last couple months I am getting has much information has I can to build a vpincab.

I have read about pinscape expansion boards and it seems to be a very good solution, but it seems that a lot of people is going the route of a pinscape with mosfet, like in the diagram below.

 

I know that there is no rule on how to build a pincab, but can anyone explain what are the differences between the two approaches? And why people is following the second one?

 

 

 

 

[Krodak]

I went the route of building all three at once. I felt at the time, that even though I didn't need it now that I might in the future. One of the common themes is that you never really seem to be done in this hobby so I planned for the future. I think the biggest advantage is smaller footprint and less wiring compared to going with the pinscape KLZ25 and MOSFET power driver boards. Building all three was just a little over 100 dollars + the pinscape board. So it was pretty affordable and a fun part of the build. Plus as a shout out to mjr he has been super helpful with diagnosing a couple of small problems.

 

All in all it has been a great solution so far for me. 

[nevess]

No more comments of advantages or disadvantages of each approach?

[mjr]

 but can anyone explain what are the differences between the two approaches? And why people is following the second one [the pre-built 4-MOSFET booster boards]?

 

The pre-built boards are easier.  You don't have to source the PCBs and all of the other components, and you don't have to solder anything.  They let you build out your system incrementally, in that you can buy four outputs at a time.

 

The pre-built boards are a bit cheaper, especially outside of the US, and especially if you don't need as many ports as the expansion boards have.  If you're in the US, building the main + power board will run you $100 to $150, depending on where you get the parts.  The MOSFET boards run about $10 each, so for the same money you could buy 10 of the pre-built boards.

 

The expansion boards are a bit neater and more compact.  You'd only have 2 or 3 boards overall (connected by tidy little ribbon cables).  The expansion boards also organize the input wiring a bit better, as the GPIO ports on the KL25Z are arranged somewhat randomly - e.g., the button inputs can't be grouped together onto a single header the way they are on the expansion boards.

 

The expansion boards give you the ability to have many more ports overall.  With the pre-built MOSFET boards, you're limited to the GPIO capacity of the KL25Z.   At the absolute most, you can have about 45 output ports - but that assumes you don't want any plunger or button inputs.  If you do want plunger and/or button inputs, you have to trade those against output ports.  In the default standalone KL25Z configuration, 22 ports are allocated for buttons, another several are allocated for the plunger, and about 22 are assigned for outputs.  You can repartition that as you wish, but any output port you add will take away one of the inputs. 

 

And importantly, the KL25Z is limited to 10 PWM-capable ports.  PWM is necessary if you want to be able to dim a light or modulate a motor speed, so it's basically required for all flashers, button lamps, and the shaker and gear motor ports.  10 PWM ports isn't enough for the standard 5-flasher set.  In contrast, the expansion boards give you 16 PWM ports for the flashers on the main board, another 16 PWM ports for low-power LEDs (like flipper button lamps), also on the main board, and 32 additional PWM ports on each power board.  

 

 

So, to summarize the respective trade-offs:

 

MOSFET boards:

  - easier

  - may be cheaper for smaller systems

  - limited to 20-40 ports overall

  - limited to 10 PWM ports

  - output ports trade against input ports

 

Expansion boards:

  - almost unlimited ports

  - almost unlimited PWM ports

  - neater

  - more compact

  - may be cheaper for a large system

[nevess]

Thanks mjr

[mjr]

I should add that you can work around the port and PWM limits in the standalone design by using more than one KL25Z.  That's why they used two KL25Z's in the diagram in the original post.  That works, but of course it makes things a little more complicated to set up, and adds to the cost.

[STV]

We've recently come to find that these red boards have a build flaw.  Namely - the logic GND from the low power signal side is coupled to the GND from the higher power toy side.  The opto-isolation isn't present.  They've hardwired the GNDs together around the optocoupler.  Whether this is a concern great enough to worry is somewhat philosophical.  

 

Check Adam's documentation of the problem here:  https://drive.google...9Bv3gBdO6NDa-q8

 

It's not certain that every red board ever made has this flaw.  Adam shows how to test it in his doc.

 

That being said - I've been using the red boards for a year, no problems.  But I haven't had any toy fail in such a way that would expose the design flaw...  

 

There is a "better" mosfet board that's been around for a while - I'm calling simply  "green board".  These better green boards can be found by searching for "4 Channel Relay Module FET Field-Effect Tube Module NMOS FR1205".  Set the pinscape to negative switching "Active low port" and they work great. 

 

These green boards have a 1k resistor on the signal, they have a protective diode on the output side..   You can put 12V or 24V on em and the voltage stays within spec across the transistor.  Although just barely... 19.5 V  and they're rated for max 20V.

 

Anyway - the best answer is of course to build MJR's pinscape expansion boards.  But if you're not keen on that these green boards work a treat.

Edited by STV, 28 June 2019 - 08:47 PM.

[MikePinball]

I recently looked at building a MOSFET board with SMD components (like the green board). The problem is that it is difficult to provide enough heat dissipation with a SMD MOSFET. The through-hole component is much better, even with just air around. So the green board may be ok for contractors and LEDs but I'm not so sure about solenoids.

 

So far the MJR design is a winner in my book (and much better than relays and other MOSFET boards).