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Self actuating two terminal voltage switch

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Hello All,

I am looking for circuit ideas/devices or advice/opinion for:

1) A two terminal switch.
2) Switch closes when voltage across switch crosses over a certain threshold say 5V.
3) Switch opens when voltage falls back to a lower threshold say 0.5V or 0V.
4) There is no power supply to run this switch. So no uC's or other conventional switching solutions.
5)The application is a capacitor based relaxation oscillator for energy harvesting from solar cells or piezo-harvestors.

Additional notes:
1) Maximum ON state current: 2mA
2) OFF state leak current has to be less than 100nA.

What I have seen till now:
1) A company called Radent MEMs, makes some 3 terminal MEMs switches, but the actuation voltage is too high (~100V) and shorting the terminal is advised against.

2) A twin BJT based circuit which looks like a thyristor with a resistor between the bases. This works to certain extent :), but, the leakage current is 10uA and the lower threshold voltage is too high (1V) :mad:.

Any advice/comments or opinions is welcome.:confused:



Well-Known Member
Most Helpful Member
Sensitive SCR like a C106???


Well-Known Member
Most Helpful Member
Sensitive SCR like a C106???
The problem is that all SCRs have a two diode forward voltage drop which is above the op's 0.5V limit.

Don't know of any two terminal latch that will stay on below 1V.


Well-Known Member
Time for a circuit redesign. If it is going to need multiple components to build this "2 terminal switch" then just use multiple comonents to build the relaxation oscillator to desired spec.
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