If you had the time and motivation, provide two designs. Requested and Recommended. I know that would blow me away. My philosophy is I always appreciate alternate solutions, but I get to pick the final design.Of course it's also possible they want to see how you perform under pressure, whether you are willing to sacrifice good practice and safety just to satisfy management. Just sayin'.
I've already explained that it's for an interview for an internship. The task is purely to design the circuit, no construction involved.To prevent this thread from being closed (like your thread on another forum), maybe you should clear up what this is for. Paper exercise, model rockets, NASA...?
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Of course it's also possible they want to see how you perform under pressure, whether you are willing to sacrifice good practice and safety just to satisfy management. Just sayin'.
I'd been considering this and I think as it's a task for candidates who aren't expected to have a detailed knowledge of electronics they have probably simplified the problem and are just expecting us to address the brief. However, they could well be expecting stronger candidates to suggest improvements. I think I'm going to try to tackle the given problem first, and if I manage that I could try also talking about changes which could be made to the circuit to make it safer.If you had the time and motivation, provide two designs. Requested and Recommended. I know that would blow me away. My philosophy is I always appreciate alternate solutions, but I get to pick the final design.
Thankyou! That's such a helpful response. I'd already tried to break down my plan so that each aspect was addressed individually, but I'd not even considered the details you'd mentioned and I think they'll be really good things to talk about.Wow, that's a lot of stuff. Ih, this is probably an exercise in thinking more than designing. So think about the problem this way. First, what does it take to fire a squib (pyrotechnic ignitor)? Why did they give me a switch that is normally a short circuit? How can I use that to ensure the squib can't fire accidentally (safety is paramount)? What does the short pulse tell me? Why is it there? Maybe I can latch it so I know it happened, but it doesn't have to drive anything. What does the logic signal tell me? Could it imply a push button that has to be held down long enough for the squib to fire? Could it be a timing window gate? And lastly, when it comes to safety and reliability I have a simple formula....the only thing that will never break is the device that isn't there. So think about how the arming system could be made with the least number of parts, arranged so they are as safe as can be. Hope that helps, and good luck with the interview.
Thanks so much for this but I'm far too new to this to fully understand that circuit. I was going to try to design the circuit so that it had 3 latches that would be set separately by each event. Then, all 3 inputs would go to an AND gate which would initiate the device only when the latches had been set. Does this sound about right to you? I've been doing my research on latched circuits and I think I've got a grasp of how they work and how they can be used, but I'm still unsure about how I would put 3 of them together to get the result I want.Here is a sketch of what a firing circuit might look like.
A Manual NC pushbutton SW.
B Pos. pulse triggers 30 sec. OS.
C Lo to hi logic signal triggers a 30 sec OS
All 3 states are monitored by red & green LED's. If all green we should hear the bang.
Select transistor for current required by squib.
Note that 74AC series can source or sink 24 mA.View attachment 97206