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matthew where near that where near that
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Re: clust-o-matic

Postby matthew » Sun Nov 25, 2018 4:26 pm

CATO wrote:Hi Matt,

matthew wrote:Does the LED actually do anything useful?.

If you don't like it, don't include it, but when I connect the e-matches to the terminals I would like a visual indication that the circuit is not in a triggered state...

Great, that's useful info. I was thinking that no-one would have their avionics powered up when connecting igniters, but I guess there's always the possibility of misconfigured wiring. Easy enough to have them (one per input in my case).

matthew wrote:I'm also looking at a layout that should greatly increase the current available to each igniter simultaneously. Probably this will entail a solder on fly lead for connecting the battery rather than screw terminals. Is that a deal breaker for most people? It isn't a problem for me, but I know how to solder...

How much current do you need? Each FET is capable of 14~15A depending on the version, the trace is calculated for 30A (80 deg)...

I think with the bus style of the Clust-o-matic, it shares that 30A amongst all 4 FETs. In particular, that first part of the trace as it leaves the battery terminals could be a bottleneck in a 4x 15A continuous scenario. I want to make the 15A available to each FET at a lower temp. Temp means resistance which means a voltage drop across the trace, reducing the voltage across the e-match/igniter (also wasted energy from an already small battery). I'm thinking of the dead-short scenario: if one or more FETs is switching 15A, then it reduces the current available to the others.

My limited searching for 5.08mm pitch screw mounting terminals has only been able to turn up parts that are rated to a max of 16A. As a battery connection, that creates a limit. By going with a solder on tail, I'm hoping to be able to transfer that amount of current (4x 15A) to the board reliably.

That all said, I'm not aware of any issues anyone has had with the Clust-o-matic and there's no doubt in my mind that what I'm doing is likely overkill. I'm just taking the opportunity to see if an already good design can be taken another step or two with a fresh look. I'm also thinking about possible further applications, like at the pad. No relay contacts to burn out or getting welded together. :)
Matthew Small
AMRS #33 L3
TRA #11466 L3
QRS #133

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Mr Smiley
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Location: Sydney, NSW

Re: clust-o-matic

Postby CATO » Sun Nov 25, 2018 5:08 pm

Good luck with you build Matt......
"In thrust we trust"

AMRS 21 L3
TRA 07459 L3

2018: 14,767 Ns (44% N)
Ns 17: 5,973; 16: 34,558; 15: 35,955; 14: 6,016; 13: 10,208
PB - Gorilla N2717WC, H: 10,260', S: 1.14M

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