push-push on/off switch

What? And what does it do ?:-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

Cool.

A sort of oscillator?

VLV

I think if you hold in the button, the negative feed back will bias the mosfet half-on (destroying it if load is too heavy).

Is this an "I can't believe nobody else has thought of that yet" moment?

Thanks, Rich

No, but if someone holds the button long enough it'll be a "Phsssst - pop - crackle - KABLOUIE" moment.

It works as a dimmer, too.

It's interesting to play with.

John

Why would it oscillate? No, it's a push-push on/off switch.

John

...Jim Thompson

Bwahahahahaha!

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

--- Not according to LTSPICE:

Version 4 SHEET 1 880 680 WIRE 208 -352 -272 -352 WIRE 208 -288 208 -352 WIRE -272 -176 -272 -352 WIRE 0 -176 -32 -176 WIRE 208 -176 208 -208 WIRE 208 -176 80 -176 WIRE 208 -112 208 -176 WIRE -32 -32 -32 -176 WIRE 32 -32 -32 -32 WIRE 160 -32 112 -32 WIRE 48 16 -176 16 WIRE -176 48 -176 16 WIRE -32 64 -32 -32 WIRE -272 160 -272 -96 WIRE -176 160 -176 128 WIRE -176 160 -272 160 WIRE -32 160 -32 128 WIRE -32 160 -176 160 WIRE 96 160 96 16 WIRE 96 160 -32 160 WIRE 208 160 208 -16 WIRE 208 160 96 160 WIRE -272 208 -272 160 FLAG -272 208 0 SYMBOL nmos 160 -112 R0 SYMATTR InstName M1 SYMATTR Value FDC637AN SYMBOL res 192 -304 R0 SYMATTR InstName R1 SYMATTR Value 12 SYMBOL res 96 -192 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R2 SYMATTR Value 1000 SYMBOL cap -48 64 R0 SYMATTR InstName C1 SYMATTR Value 1e-7 SYMBOL voltage -272 -192 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 12 SYMBOL voltage -176 32 R0 WINDOW 0 -53 5 Left 0 WINDOW 3 -242 110 Invisible 0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value PULSE(0 1 2 1E-6 1E-6 1 2) SYMBOL sw 128 -32 M270 WINDOW 0 32 15 Left 0 WINDOW 3 32 44 Left 0 SYMATTR InstName S1 TEXT -184 232 Left 0 !.model SW SW(Ron=1 Roff=10Meg Vt=0.5Vh=0) TEXT -184 200 Left 0 !.tran 10

Or maybe I picked the wrong parts. Got some values that work?

-- JF

My sincere apologies to LTSPICE, but it does work.

Try, say, 1M and 0.47 uF.

John

Yep, It will work for optimal button-press times. Then it will leak one way or 'nother ;-)

It's fun that it works, but otherwise useless.

...Jim Thompson

Does everything that's fun have to be useful?

John

No. But a stable-state switch would be more interesting.

...Jim Thompson

Fry when it eventually drifts into the linear region?

Best regards, Spehro Pefhany

Your sketch, for the permanent record,

,---/\\/\\----+----o LOAD o-- +V | | | |--' | ___ ||>>> A sort of oscillator?

A 0.5-s time constant. Should work with most modest pushbutton presses. My experiments show modern power MOSFETs can hold their gate voltage for days, if not weeks. But surely you remember out long-running thread that completed the simple circuit with a 2nd transistor making a flip flop.

The problem is that there is NO stable state to start from. A true F-F is the only way to go.

...Jim Thompson