444 replies to this topic

[zebulon]

Board order has shipped, am expecting them in 2 weeks or so.

[Lynny]

Board order has shipped, am expecting them in 2 weeks or so.

Zebulon,

Excellent work on this, I know you've heard that a few times by now, lol..but it is, really nice. Put me in for 2 high power, bare boards when they arrive. Just let me know when and where to pay..

I may never need them..but if I ever do..I want to be ready.

I have an LedWiz just sitting in the package, and right now I just wanna hook up a kicker solenoid I robbed from an old machine..still looking for a shaker to rob from something.

Peace,
Lynny

[Dazz]

I got both the Medium and High power boards. I can't wait until I can find the time to get around to getting my cabinet re-wired. Special thanks goes out to Zebulon and Maxsinner!

[zebulon]

Board order has shipped, am expecting them in 2 weeks or so.

Zebulon,

Excellent work on this, I know you've heard that a few times by now, lol..but it is, really nice. Put me in for 2 high power, bare boards when they arrive. Just let me know when and where to pay..

I may never need them..but if I ever do..I want to be ready.

I have an LedWiz just sitting in the package, and right now I just wanna hook up a kicker solenoid I robbed from an old machine..still looking for a shaker to rob from something.

Peace,
Lynny

Thanks Lynny, I'll let you know when they come in.

I got both the Medium and High power boards. I can't wait until I can find the time to get around to getting my cabinet re-wired. Special thanks goes out to Zebulon and Maxsinner!

Glad to hear that you got everything Dazz, thanks again to Maxx for making that happen.

[maxxsinner]

I got both the Medium and High power boards. I can't wait until I can find the time to get around to getting my cabinet re-wired. Special thanks goes out to Zebulon and Maxsinner!

Glad to hear that you got everything Dazz, thanks again to Maxx for making that happen.

Great to hear your all sorted now Dazz. Thanks to you Zeb for these awesome boards!

[zebulon]

Got an update on shipping and I expect to receive the board order in the coming week.

Have ordered a second batch as the 1st batch to arrive have almost been completely spoken for.

Thanks all!!

[Spektre]

Hey Zebulon,

This is a design philosophy question.

Why did you decide to continue the active low design of the LED Wiz with your booster board?

From an EE perspective, this switching method seems bass-ackwards to me.

The (IMO) standard method of switching would be to run a common Ground to all devices (LEDs, motors, etc.) and to current source.

The current LEDWiz method (followed with the booster board) is to current sink.

If we were dealing with very low power logic chips I'd get it, here not so much.

This method requires all the various devices to be floating in the cabinet and the various voltages they operate at. Mistaken bridging in this situation of two devices operating at different voltages (even when NOT active) can result in failure.

Doesn't affect a great design for a needed device, but curious if you have a reason why the LEDWiz and your booster board follow this (IMO strange) current sinking method.

Spek

[Spektre]

Also a question,

With the N MOSFET you are using in this design, there is no need under most ANY reason to use more than just 5V for the bank selections on the LEDWiz for banks destined for your board right? In other words, if I have a 24V device, I can switch it at 5V on the LEDWiz and do the 24V switching on your board.

It also let's you do some cool stuff like run some LEDs @12V off the same LEDWiz PWM signal that is running others at 5V!

Would you mind posting a board schematic Zeb. It might stop some future questions

Edited by Spektre, 02 July 2012 - 12:07 AM.

[zebulon]

Hey Zebulon,

This is a design philosophy question.

Why did you decide to continue the active low design of the LED Wiz with your booster board?

From an EE perspective, this switching method seems bass-ackwards to me.

The (IMO) standard method of switching would be to run a common Ground to all devices (LEDs, motors, etc.) and to current source.

The current LEDWiz method (followed with the booster board) is to current sink.

If we were dealing with very low power logic chips I'd get it, here not so much.

This method requires all the various devices to be floating in the cabinet and the various voltages they operate at. Mistaken bridging in this situation of two devices operating at different voltages (even when NOT active) can result in failure.

Doesn't affect a great design for a needed device, but curious if you have a reason why the LEDWiz and your booster board follow this (IMO strange) current sinking method.

Spek

Convenience and courtesy explains why I designed them the way I did.

Convenience from the fact that I designed these originally for my cab and didn't want to have to rewire the entire cabinet in order to install them. As everything in my cab was already wired common positive, I saw (and still see) no reason to use PnP switching instead of NpN. The courtesy factor was a nod to another board member whos project involved a board design that he had that uses common ground, I saw no reason to duplicate someone else's work.

As to your question about the ledwiz design, I dunno, I had nothing to with that. If I were to hazard a guess, I'd say that the switching is done that way because they use a Darlington transistor circuit design that inverts the input signal on output. Since the input into the uln2083 chip is positive, the output naturally would be negative. Since the driver handles more than enough current for the originally intended loads, why go to more expense to invert that output to a positive one?

Truth be told, I really see no reason to change the design. Mistaken bridging as you put it is as preventable as wiring a dead short, either of which can happen. I'm sure there are different and better ways to design this circuit, as with everything in electronics, there's always room for improvement. But as it is, there's around 60 sets of these boards in use at the moment and without jinxxing myself, I've yet to have someone contact me with any issues beyond a couple of lost in transit shipments.

Also a question,

With the N MOSFET you are using in this design, there is no need under most ANY reason to use more than just 5V for the bank selections on the LEDWiz for banks destined for your board right? In other words, if I have a 24V device, I can switch it at 5V on the LEDWiz and do the 24V switching on your board.

It also let's you do some cool stuff like run some LEDs @12V off the same LEDWiz PWM signal that is running others at 5V!

Would you mind posting a board schematic Zeb. It might stop some future questions

You really don't even need the 5v at the bank selection on the ledwiz, that just runs the clamping diode built into the ULN2083, and with no inductive field to collapse on the booster board, that diode has no real function.

Yeah, I try to use the enhanced mosfets whenever possible, with the added amperage and voltage rating, they have great flexibility in their usage and how much abuse they can take. I've run them at 5, 12, and 24v simultaneously off the same output driver and input signal. Wasn't my original intention but it's nice to know that it works when necessary.

I sent you a schematic a few months back in you email when you asked for it but I have nothing to hide, I'll post it on the documentation posting.

[maxxsinner]

Spektre, can you post a schematic of your current source design that you are refering to?
Sounds like you have some ideas of another design and some strong opinions and I would love to see for a comparision.

[Spektre]

Spektre, can you post a schematic of your current source design that you are refering to?
Sounds like you have some ideas of another design and some strong opinions and I would love to see for a comparision.

Will do. Strong opinons might be a bit...strong LOL.

I am a big fan of the, "Hey, if you can design better, there's the drawing board." philosophy.

Zeb's board is great and does what it is supposed to. I bought one, and will most likely be getting a second. Being compatible with a table that was already wired to use the LEDWiz and relays is all the design justification I need to hear.

For a brand new unwired cabinet though, a current source design would have some advantages. I'll fire up an art program and draw up what I mean today.

------

For Zeb,

You did indeed send me a schematic a bit back. My memory isn't what I remember it to be. Thanks.

[maxxsinner]

I am a big fan of the, "Hey, if you can design better, there's the drawing board." philosophy.

Could not agree more, hence the request to see what you come up with. Another view point never hurts.

Zeb's board is great and does what it is supposed to. I bought one, and will most likely be getting a second. Being compatible with a table that was already wired to use the LEDWiz and relays is all the design justification I need to hear
For a brand new unwired cabinet though, a current source design would have some advantages. I'll fire up an art program and draw up what I mean today.

Not sure what advantages there could be? In my new cabinets I am building, I am going to have 5 different voltages; 3.9, 2.7-3.9 variable, 5 volts, 12 volts and 24 volts, and if I was current sourcing I would need to run each of these voltages onto the booster board and have all of the signal paths isolated from each other.

In a current sink board, I dont. Straight from the power supply to each device. Bridge the negative outputs together from all of my power supplies to a common point and the booster board does the rest. A common wire to control all of the different voltage devices.

Your concern of a mistaken bridging between different voltages is more likely if they are all run to a common board IMO. Seperated to each of the devices, a bridge is very unlikely.



Look forward to seeing your design.

[Spektre]

I am a big fan of the, "Hey, if you can design better, there's the drawing board." philosophy.

Could not agree more, hence the request to see what you come up with. Another view point never hurts.

Zeb's board is great and does what it is supposed to. I bought one, and will most likely be getting a second. Being compatible with a table that was already wired to use the LEDWiz and relays is all the design justification I need to hear
For a brand new unwired cabinet though, a current source design would have some advantages. I'll fire up an art program and draw up what I mean today.

Not sure what advantages there could be? In my new cabinets I am building, I am going to have 5 different voltages; 3.9, 2.7-3.9 variable, 5 volts, 12 volts and 24 volts, and if I was current sourcing I would need to run each of these voltages onto the booster board and have all of the signal paths isolated from each other.

In a current sink board, I dont. Straight from the power supply to each device. Bridge the negative outputs together from all of my power supplies to a common point and the booster board does the rest. A common wire to control all of the different voltage devices.

Your concern of a mistaken bridging between different voltages is more likely if they are all run to a common board IMO. Seperated to each of the devices, a bridge is very unlikely.



Look forward to seeing your design.

I think you hit on the exact issue there, but I am not sure how you consider it an advantage.

In the current source design, presumably, you could place your power supply (supplies) in close proximity to your booster board. Each voltage would be run to the booster board and that is that. The various devices could all use a bussed GND in a manner similar to your input switches. (Indeed, it could use the exact same GND bus)

In the current sink design, not only do you need to run a switched line to each device, you also have to bus ALL the various voltages around your cabinet, to devices which, again presumably, are not able to sit right next to each other.

I'm including a block level example of the two designs and you can see the difference in complexity. In the proposed design a GND bus is sent around the cabinet and you tie onto it at various points. When the power to a device is off, it is "off".

In the current (present) method, all the various devices float at the various voltage in the cabinet. When the power to the device is switched off, it is still "ON" if YOU happen to be grounded. More practically though it requires additional wires to be run through the cabinet.

My two cents, from the guy who did not bother to design a booster board. This is not a knock on the current design.

[maxxsinner]

Appreciatethe feedback Spektre.

Not to steal away from Zebulon as obviously this is his design and thread but please allow me to retort.

The main issue I can see with the current source design is you are instantly limited towhat voltage you specify in the board design. i.e. bank of 4 outputs for 5volts, bank of 4 outputs for 12 volts etc, or you would need to run a separate supply for each individual input for the source voltage. More connections, more components, larger board due to the need to isolate traces = more cost in the design.

Floating voltages are not dangerous or even uncommon (unless its mains voltages). We often use sink inputs/outputson our PLCs controlling plant at a power station! So it's far frombass-ackwards as you say.
The correct way to wire a current source design with multiple power supplies isto wire each individual item back to a star point also, so there is no difference in resistance on the ground bus for each power supply or stray voltages can occur.

Personally,I prefer the ground switching method for many reasons.

Apologies if it seemed as if I was on the attack in my previous posts too Spektre. With comments like "bass-ackwards", "design justification that I needed to hear" it did certainly seem antagonistic and as though you were having a dig at the design of someone's hard work and effort that he was willing to share with the community. But you have cleared that up with your last sentence.

Please elaborate on the source design for us, what IC's etc you would use. Really love to see new ideas come to life.

Edited by maxxsinner, 04 July 2012 - 06:02 AM.

[Spektre]

Appreciatethe feedback Spektre.

Not to steal away from Zebulon as obviously this is his design and thread but please allow me to retort.

The main issue I can see with the current source design is you are instantly limited towhat voltage you specify in the board design. i.e. bank of 4 outputs for 5volts, bank of 4 outputs for 12 volts etc, or you would need to run a separate supply for each individual input for the source voltage. More connections, more components, larger board due to the need to isolate traces = more cost in the design.

Floating voltages are not dangerous or even uncommon (unless its mains voltages). We often use sink inputs/outputson our PLCs controlling plant at a power station! So it's far frombass-ackwards as you say.
The correct way to wire a current source design with multiple power supplies isto wire each individual item back to a star point also, so there is no difference in resistance on the ground bus for each power supply or stray voltages can occur.

Personally,I prefer the ground switching method for many reasons.

Apologies if it seemed as if I was on the attack in my previous posts too Spektre. With comments like "bass-ackwards", "design justification that I needed to hear" it did certainly seem antagonistic and as though you were having a dig at the design of someone's hard work and effort that he was willing to share with the community. But you have cleared that up with your last sentence.

Please elaborate on the source design for us, what IC's etc you would use. Really love to see new ideas come to life.

Apology accepted. If I were criticizing a design, I wouldn't start with phrases like "design philosophy". A designer often has something specific in mind that takes him to his method of skinning a cat. Zeb stated his.

You would indeed need to bring each of your voltages to the booster board, but the board itself need not be designed with the voltages in mind. Simply leave a connection hanging per device. Yes, the booster board would then have to have 3 connections per device instead of its current 2. (Control, Voltage IN, Voltage OUT). No additional components save a screw post per device. The idea of "banks" on the LEDWiz is due to its specific driver IC. In this high power board, there are individual drivers allowing each output to have its own voltage. (By the way, Zeb's drivers work "better" even for lower powered devices. The voltage drop across his "switchs" is less than 0.1V, compared to ~1.2V on the LED Wiz. Less voltage drop = brighter LEDs, cooler boards.)

Floating voltages are only dangerous if you happen to be grounded; a not infrequent occurance.

The "correct" way to wire Ground in a circuit is complex and a one size fits all "always use a star configuration" is only right...well, when its right. For example in radio applications, I would use a star. In networking applications, I would use a bus. (And even both of these general rules have exceptions depending on what your trying to optimize for). Given the application of a pinball cabinet and the typical devices used in such, I would say noise concerns are negligible save for if you are using a DC powered audio amp, and then I would only wire the worrisome component directly back. Lastly remember, when you are switching ground, ground is no longer Ground. It is Ground thru a switch (some voltage >0). Zeb's drivers are quite low voltage when on, but they aren't 0.

All these words for what is not a huge issue. Current sinking works. It works here.

The only design critque I had, I brought up very early in the thread (trace width) and that might be the overspecing engineer coming out in me and would most likely result in a larger board. The drivers Zeb has picked have so much headroom though that you could really drive them hard with bigger traces. The current .012" traces really should only carry ~1.5A. Since most of the outputs are not steady state, that ups this a bit, but I hve concerns my solenoids that draw 4.5A are going to peel traces At the rate my cabinet is getting built, I'll find out in a year or so LOL

Edited by Spektre, 04 July 2012 - 07:46 AM.

[zebulon]

Spektre, does your board have a ground plane printed on the back? If not, you've got one revision back on the boards. It'll still do the 4.5a, but don't let it stick on or you may pop the trace.

The traces that needed to be heavier on the board were bumped up to .024" - .032" and a ground plane was added.

Let me know if you need a heavier board, I can send replacements.

As for the pos switching, I still think that common sense should be a factor in everyone's build. Don't wire your cabinets while the power supplies are hot. I get what you're saying, but it would be a far bigger and more expensive board to pull off.

[zebulon]

Boards arrived today, started assembly for those that are waiting, a quick pic of some of them.... who's idea was assembling by hand anyway???

Should have them all assembled and shipped by the 9th as promised!!

Thanks for being patient!!

[Gigagamesguy]

You only need fuses on the power supplies when using these boards GGG

ok, when i right understand it, i only use a fuse between the meanwell amp plus side to the tools and led's

from my psu amp to the powerboards on the plus5 and plus 12 volt a fuse

i dont understand the fuse problem, pleas help me, with a smal diagramm

[zebulon]

If your power supply has a fuse, rely on that.

[maxxsinner]

As Zeb said, it should have an onboard fuse but Meanwell PSU's also have Overload, short circuit and thermal cutouts so I would not be too concerned GGG