push-push on/off switch

Show it ;-)

...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  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

OK here is the ONE active component semiconductor version:

U1 U2

+250 +12 |-- | | | | P1- R2 -- ------ +12V | | | | | |----R4 ----- |_| sync 0V R1 | | | | |--- |-------\\| UJT | |--- |-> o ut | C1 R3 | | /// ///

P1 is a potentiometer that sets the frequency, by controlling the charge current in C1. The generated sawtooth is linear with in few percent, more if U1 is higher. Sync lowers the UJT voltage a bit via R2 / R4 to cause early trigger (normally it runs at f < normal).

This is an old trick to get a linear ramp, and in fact the tube circuit uses it too I think. As C1 charges, the current becomes (U1 - UC1) / (P1 + R1). For a fixed UC1 (about 6 V in this ciruit), much smaller then U1, the charge current IC1 depends mainly on U1 / (P1 + R1). QED.

Can't figure it out?

Actually, it might be possible with one more part.

John

You will not.

Really, that's about the ugliest schematic in human history. If you want to sell your software, that's sure not helping.

John

Add a small-signal MOSFET and a resistor.

Best regards, Spehro Pefhany

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speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Fun, useful, stable-state, and interesting.

(Maybe not so useful as it once was.)

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