Need a way to energize a coil based when 4 switches go down...

[patrick99e99]

I have a 4 switch circuit that has 8 pin outs:

STB, SW1, SW2, SW3, SW4, GND, GND, +5V.

STB has 4.6v constantly
SW1-SW-4 are 0.15v when off, and 0.65v when down.

I am looking for a way to make it so that when SW1, SW2, SW3, SW4 are all equal to 0.65v each (so 0.65v * 4, or 2.6v), then I want to trigger sending 50v to a coil for 1 second, and then cut off the 50v.

So, I am wondering what my options for this are? Do I want to use transistors to construct AND gates, to detect when all 4 switches are ON? Or is there an easier way to do this? I also am unsure what my options are for limiting the 50v for a one-time 1 second time interval.

I'd love to hear whatever creative ideas you guys might have on this...

Thanks!

 

[alec_t]

so 0.65v * 4, or 2.6v

Are you sure? Aren't all of SW1-SW4 at 0.65V relative to GND when 'on'?

 

[dougy83]

You can connect the 4 switch outputs through resistors together to form a summer, then feed this to a comparator with a set point just below 0.65V, and some hysteresis. The output of the comparator can feed into a monostable multivibrator which can control a transistor to turn on your coil.