Whooshtronics Clust-o-matic

I won one of these in the raffle at LDRS XXX in Argonia, and really like the idea, so I sent off an order for a few more. One is going in my two-stage Seahawk, so I can use two igniters to light the upper stage motor. Two more are going in "Featured Scientist" to light up to 8 ematches. (airstarting perimeter motors). The question I have is "how would you connect the circuit board to an avionics sled (3/16" plywood or 1/8" G-10) if the circuit board has no holes to accommodate stand-offs. You guys with electronics experience... can I / should I just epoxy it to the sled, or try and drill new holes in the circuit board, double-sided tape, etc. What works, hasn't worked, voids the warranty, etc. Thanks. Sather

https://www.whooshtronics.com/products-t83/clust-o-matic.aspx

[video=youtube_share;E_xT1SjAtN8]https://youtu.be/E_xT1SjAtN8[/video]

You could try a snap-in or drillable card guide like those at vaisis.com or richco-inc.com. Digi-Key or Mouser might have them in small quantities.

It looks like there is enough room on the board in at least two corners with no traces. I would drill #4 through holes in those open areas and mount the board. I definitely would not epoxy it.

Plastic zip ties!

Adrian

Very nice product. I have always wanted on of there apogee detectors.

I would design my own pcb in Eagle with mounting holes and get the boards made with solder mask, silkscreen and properly sized traces not undersized traces with gobs of solder added to it. If I were you, I would just drill out the top corners from your image. The backside looks clear of traces in those places. I'm not sure you'll fit a #4 standoff without touching a trace. Ideally you'd use a pcb drill which is like a Dremel on a quill but being careful on a drill press should be fine. All your traces are on the surface so if they crack it'll be readily apparent.

Thanks, guys. Yeah, it gets a little more frustrating than that. One of my three is a pre-production version, like the one shown on their website, the green printed circuit board with solder added to the woefully small traces. The other two are production models with black PCBs. You can find my opinion on opaque G-10 in various places around TRF... I am not a big fan of it - only because you can't see thru it.

There is basically no edge to be able to use a card guide, and no usable surface area to drill holes. I like the zip-tie idea, as it is easy to do and reversible. ("UNDO" was my favorite feature when the Mac came out in 1984.) Also, there are terminal blocks on three sides of the PCB, so if I use heavy wire, the PCB would be held down like Gulliver in his travels. Still thinking there has to be a better way to do this. Why would they have designed a circuit board, intended to be used in a rocket, without a way to secure it?

velcro?

cwbullet said:

Very nice product. I have always wanted on of their apogee detectors.

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A nice bunch of guys from down under, and they do make great products. Interestingly, they did include mounting holes on the uMAD... possibly of note because it has to be installed upside down here in the northern hemisphere. :smile:

cwbullet said:

velcro?

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That is the leading candidate right now. I found some velcro with really sticky backing on the other sides, which might be sufficient to hold the circuit board under "G".

You could use a piece of prototboard to create a motherboard/daughterboard arrangement with the clusto-matic board. The protoboard would provide a place for standoffs to mount this assembly to your rocket. You'd be stacking the clusto-matic on top of protoboard and connecting them by replacing the two smaller terminal blocks with male headers which mate with female sockets on the protoboard. This would also serve to bring the electrical connections down to the protoboard where you'd install new terminal blocks and jumper the terminals to the female socket.

Look at how these two boards are attached to see how this works.

cwbullet said:

velcro?

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I didn't know this until today, but Velcro has some static electricity issues. Found this while catching up on other threads, so back to the drawing board...

blackjack2564 said:

Velcro can store and release static electricity.....the bane and destroyer of many types of electronics.

That is the issue.... not how secure it can hold.

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I'm going to give this a try. It sounds like some really strong double-sided tape.

r1dermon said:

There is a 3m material available at walmart, or if you have an ez pass, you can get new strips for free. It holds very strong and doesnt let go, its not velcro, I cant imagine it would have the same elecrostatic properties as velcro. Alternatively just use zip ties.

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SMR said:

I'm going to give this a try. It sounds like some really strong double-sided tape.

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I don't think it's double sided tape. The stuff on my ipass is detachable like velcro but the connection is formed with an array of little plastic balls on flexible stems that interlock. Radioshack carries it by the zip ties and such.

I would be hesitant to trust this, as the interaction between the two strips could produce static electricity, much like Velcro...

G.D.

Naw, I wasn't planning on the I-Pass version of Velcro... I have an I-Pass and wouldn't have needed to go to Walmart. But he mentioned "3M", which got me thinking. Adhesives and abrasives are 3M's claim to fame, surely they must have something suitable for this. Behold - their permanent mounting tape. It is relatively thick for tape, 3/32" or so, with a soft foam-like core that could cushion some vibration. And with an advertised hold strength of 2 pounds per square inch, (which isn't defined it as shear or tension), would hold the 2 square inch, 0.6 ounce Clust-o-matic to over 106 G's. (More. actually, since the wiring adds some physical structure as well.) I got two versions, will test and use the stronger one.

Sather...I just post a link to your thread on the Ozzie's forum:https://www.ausrocketry.com/forum/viewtopic.php?f=32&t=4252


Hopefully you will get an answer as to how thy use them soon. CJ

What about zip ties? I'll try to make up more words which might describe what I'm thinking.

Take a block of ply about the size of the board. On one side cut groves (datos) running the length and width of it which are big enough to hold your zip tie. Screw this board to your av bay. Then wire up the board, place it over this piece of ply, then use zip ties which pass over the board and under the ply through the groves you've cut. The zip tie would be sandwitched between the ply and your av bay board.

Kevin

Thanks, CJ. I had tried emailing sales at Whooshtronics, but it didn't go thru. Then I wrote one of the Aussies I met at LDRS XXX, who was going to pass my question along but haven't heard back yet. Aussie forum was a great idea. Sather

kruland said:

What about zip ties? I'll try to make up more words which might describe what I'm thinking.

Take a block of ply about the size of the board. On one side cut groves (datos) running the length and width of it which are big enough to hold your zip tie. Screw this board to your av bay. Then wire up the board, place it over this piece of ply, then use zip ties which pass over the board and under the ply through the groves you've cut. The zip tie would be sandwitched between the ply and your av bay board.

Kevin

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Thanks, Kevin. Zip ties were looked at, but I was worried that anything they hit or touch might damage the electronics on the top side of the board. Like picking up a child by the hair. (Okay, that was a disturbing analogy, but you get what I mean.) The bottom of the board is relatively smooth, so I'm still leaning towards the super sticky tape. Sather