Scubasteve said:
Oh, I see what you want now. If you want a toggling function, you will need a flipflop in the configuration as you suggested, there is no way around that. I am curious to see why you have chosen that particular zener diode in place of a regulator, which isn't any more complex then a zener/resistor and will offer superior performance.
As for your scheme to drive the flipflop, it will not work all of the time! You need to debounce this switch or else it will be a game to which state it will be after you pressed the switch. There are several circuits and even chips that will do this function effectively.
You cannot find a chip for every application, especially uncommon tasks such as what you are doing. If you gave us your actual application we probably could suggest something better for you. Until then, good luck
Steve
Why would curiousity arise?! Zener diodes are cheaper.
This is to be used in several products and it will probably be changed a little here and there but basically the same. Cost is a factor. Only if I was given free components I would have used other types.
The supply voltage to the f/f is of course not critical. I tried 50k for the resistor and "7.5 V" zener which gave ca 5 Volts. And the micropower references cost a lot lot more than the standard models. But why waste money at all? The voltage at the transistor emitter gets to around 4 Volts when using a darlington, which is a condition in order not to draw too much current from the flip/flop which otherwise might lower the voltage below 2 Volts. Maybe it could do anyway because the flip/flop did the job even at 1 Volt. But the darlingtons available as cheap as standard transistors so I rather use them.
As I said, the f/f-circuit shall draw as little power as possible as long as Q=L, shunted to the zener voltage circuit. I measured some 0.2 mA which
could be ok.
The RC-combination i tried as a first try was 1 MOhm and 39nf. If the resistor is too low it will affect the zener voltage when pressing down the switch.
There is no need for de-bouncing circuits. Just a big waste of time, space and money! The capacitor filters out most micro spikes. It worked quite well even cable-to-cable. Since small switches today are of a non bouncing type they can almost be used without a capacitor. Now, with a switch type as that and the capacitor, it worked with no bouncing at all. I tried i
t hundreds of times. No bouncing. And never in earlier projects either.
This type of application is indeed very veeeery common. How do you think????????????? Have you never seen all these countless low quality stereo equipment and even more expensive gear using micro switch-toggling-power-on-circuitry, having that little red led besides?!
My actual applications? Did you ask for what comes after the regulator?
Well, that is not within the thread here and it would not affect the design. The circuit discussed here does not know what it feeds so...
Yet still, I´m looking forward to seeing better suggestions than mine.
There could be other ways, like combining a triac with something else to get the toggling function.