... do you launch at bayboro? I think I know your name. You are the club prefect? (Or used to be?)
Answering the easy bits first: I haven't been to Bayboro yet, but hope to get down there soon to watch those with more experience and bigger hobby budgets than mine fly the big stuff. I'm not a Tripoli member, have never been any kind of club official.
The
555 is a venerable integrated circuit timer chip that can (along with a few additional components) generate timing events in the range you mentioned. The IC and the necessary other parts can still be obtained as "through hole" parts (read that as: you can build with it using simple tools compared to more modern, tiny, surface-mount parts). The 555 can handle up to 200ma of current, so you would need a low-current igniter for your ejection charge if you want to try and have time timer fire the charge directly. If you need more power, a MOSFET (or other type of transistor) can be driven by the 555 to provide more current handling.
A 555 and driving a transistor switch are often early on the list of things someone does when beginning to experiment with electronics. There is plenty of documentation and example material on the web. You can probably get everything you need to prototype and test the electronics with a trip to your closest Radio Shack (except igniters).
I want to emphasize again that there are
reasons why deployment electronics "done right" are more complicated than this ... Durability, operational reliability, and safety can all suffer as you try to reduce electronics cost. Arguably the
only benefit to this approach (beyond learning) is having time-driven deployment without having to use mismatched reload components while also keeping electronics cost low enough to be considered, "disposable."
Purchase of a beginning electronics kit (here is
one example, there are many out there) and building something that will reliably fire Quest Q2G2s 17 seconds after being triggered, sitting on your workbench, could be an educational experience. Getting from there to flight hardware that your RSO will approve may give you an entirely new appreciation for how much value the vendors provide in their products.
Knowledge gained is often in direct proportion to equipment lost or destroyed, but do your best to be safe if you decide to take this path.
Cheers,
Alan
