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digital switch

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smitchell82

New Member
Hi,

Im wondering if anybody knows of a simple digital switch that will connect 2 pins on a low input and put a huge resistance between the two on a high input (just a normal digital switch).

or is there a circuit that can do the same thing?

Its for an oscillator circuit operating at up to 1kHz so if a circuit is suggested, it probably should be relatively fast. thanks a lot.

Sam
 

smitchell82

New Member
Hi, the on resistance of the switch seems to be a huge problem. the circuit i am looking at making is for a voltage controlled oscillator, where a capacitor is connected to ground once the switch is closed and discharges. with a 100ohm resistance, the capacitor doesn't discharge.

any other idea's?
 

Exo

Active Member
You could use an N-channel FET as a switch, there are fet's out there with an Ron of only few milliohms. Problem with these is that when turned off; they have quite a large capacitiy (approx 1 or more nF) between drain and source wich might also be a problem (cause small signals will still get trough due to the capacitance)

only thing besides that would be a QS3384 bus switch (10 switches)
Ron is 4 to 5 ohm and capacitance is very small. But they're only available in small SMD packages and not so cheap (over here anyway).

http://www.idt.com/docs/QS3384_DS_27540.pdf
 
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