latching

[cole7011]

other then a JK flip / flop (data-latch) what other methods of latching could be used to toggle a remote receiver  relay between an on and off state.

mcole

[Guest Alun]

There're other ways of building a latch like an SCR, or RS flip-flop, but if you want press if once to turn on and again to turn on a JK flip-flop is really the  only way to go.

[audioguru]

Here's a simple circuit that uses a capacitor to debounce the pushbutton's contacts and is a master, and a couple of inverters as a slave. Push for on, push again for off like a JK flip-flop.

[Kevin Weddle]

This circuit drags the voltage to it's one stabile state. Whenever you have a logic circuit, it always helps to decide what the initial state will be. In other words what is the startup condition and will it change. There exists a voltage that the circuit likes best, that is the stabile state voltage. When the capacitors are all charged to whatever voltage they can take on, you have arrived at it's stabile state. Now what about the oscillator. The oscillator has no stabile state because it's logic is in direct defiance and rely's on the capacitor's arrival to the correct voltage which is always going to be alternately high and low. The reason for this lies in the arrangement of the gates. Oscillators have a gate arrangement that says the logic does not produce a steady state. Like an inverter fed back onto itself with a capacitor that will charge to it's next stabile state which will in turn lead to it's next stabile state. If you think about it, the time should be very short depending on the RC. But considering it's linearity, the time should indeed be short with only the voltage having to drop or rise by mere millivolts, but for only the 1.7 volt unknown zone of the logic which leads to slew.

[audioguru]

Kevin,
I don't think my Alternate-Action Pushbutton circuit has a single "preferred" stable state. It has 2 stable states that are both the same due to the symmetrical inputs and outputs of Cmos. I think it will power-up at either stable state in a random fashion. Each time its button is pushed it changes its state to the other.

I can't think of an oscillator with capacitor feedback on an inverter unless the inverter is 2 or 3 of them or unless the inverter is a Schmitt Trigger. Please post a schematic of the oscillator you are talking about.

[Kevin Weddle]

Okay. It is a little difficult to grasp, but so is everything in electronics. The main point to my story is how the voltage will not settle in an oscillator circuit. Which is different than a 1 stabile state circuit. The way I analyze circuits is different because I see the way the capacitor charges to produce the no stabile states.

[audioguru]

Here's a discrete alternate-action circuit that also doesn't use any supply current when it is off. R1 is designed for a 1V supply and must have its value increased with higher supplies.