High Speed Switch Contact

[garywhite]

I am currently looking for some circuit ideas for latching an output on with a single switch contact. The problem is that the switch contact will only last for 10 to 20 micro seconds.

The system should preferably be powered from a single or double AA battery.

If anyone out there can point me in the right direction, I would much appreciate it.

Many thanks

Gary

 

[dspDad]

If this is a dc application, an scr might work. Use the mechanical switch to trigger the scr (through a resistor into the gate), which will conduct until disconnected or shorted out. The downside is that scr voltage drops are somewhat high, typically on the order of 1.5 volts.

For low currents, there are low voltage CMOS logic circuits that would work. A typical example from IDT is :

http://www.idt.com/docs/74LVC112A_DS_87847.pdf

This will run on 2.7 volts, sink or source 12 mA, and trigger reliably with a 10 nSec or so signal.

Except for mechanical relays, 20 usec pulses will trigger almost any electronic switch imagineable, and you might
want to provide an r/c filter in front of the triggering input to control transients.

DspDad