sON/Off switch schematic

[blort1961]

It SHOULD be a easy schematic to find ONLINE, but I'm having a difficult time finding one
I require a schematic for a switch that alternates between a on and off state every time a reed switch is activated.*
-needs to run off a dc supply between 4 and 12 VDC
-always power up in a OFF state
If you show me something with a Mosfet output, that would be great, but a relay is ok as well
Thanks in advance
*= Im only asking about using a reed switch because SOMEHOW I acquired a bag of 50 of 'em... I gotta use them in somehow...unless I start making Jewellery

 

[alec_t]

Google "toggle schematic mosfet". Several hits.

 

[blort1961]

Google "toggle schematic mosfet". Several hits.

I cant find one that states that it will power up in a OFF state, most seem to power up in a ON state

 

[alec_t]

Link us to one you fancy and perhaps we can suggest a modification, or an alternative.

 

[crutschow]

Below is the LTspice simulation of an alternate action high-side MOSFET switch that should always come up in the OFF state.
V1 with S1 simulate your reed switch.
It's shown operating for voltages from 3V to 15V.

Edit: After further simulations, I determined that my original circuit would not necessarily come up in the OFF state.
The alternate circuit below uses a CMOS flip-flop with a power-on reset so it always comes up in the OFF state (Q output high).
Note that to operate at a supply voltage of 4V, M1 needs to be a logic-level type MOSFET the fully turns on at a Vgs of 4V (specified for the Rds test voltage in data sheet).

 

[Grossel]

A series of SR latches, like a very basic PLD. That's what I would have tried.

 

[crutschow]

See my updated circuit in post #5.

 

[AnalogKid]

Here are a few examples. All of them present power up consistently in the same state and have complimentary outputs, so your output FET can be connected to either power-on state. A common feature is that the next toggle action is not available until the capacitor has charged up or down, but this delay is milliseconds. My fav is Toggle-20096.

ak

**broken link removed**

 

[crutschow]

Here is an LTspice simulation of AK's circuit as shown in his attachment, connected to a high-side MOSFET driver for supply voltages of 3V to 15V.
C1 pulls the input to U2 low at the start which insures that the circuit always powers up in the MOSFET OFF state [V(G1) high].
(It's not clear to me that the other circuits that AK posted will reliably come up in a known state, expect perhaps the first one).