Does exist on the market a differentiator device? Basically connected to a multiway switching to output a pulse of defined length everytime the deviator changes position on/off?
- Thread starter tireminnanzi
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I understand what you want to achieve and I would have expected to find a product but cannot immediately see a single unit that does this out of the box. To clarify:
You can certainly get edge-triggered relays that will output a pulse on either the rising or falling edge, and connect one of each in parallel. But there would be no control of the behaviour for multiple transitions - a single longer pulse would be the unavoidable result.
What is the application?
- A single output is to be pulsed on both the rising and the falling transitions of the input?
- What should the output do if multiple input transitions occur within the pulse duration?
You can certainly get edge-triggered relays that will output a pulse on either the rising or falling edge, and connect one of each in parallel. But there would be no control of the behaviour for multiple transitions - a single longer pulse would be the unavoidable result.
What is the application?
can be configured to do what you require.
I was thinking more in the £1 category! Obviously it's easy to design and build with discrete logic if one is electronically minded, but perhaps if we know the application we'll get a clearer idea of what level of engineering the OP is looking at.
very fast answering, this blog is really amazing.
Yes something simple in the budget. We are using this new line of products from Bticino brand where the push button is missing, only the multyway switch (great aestetics but poor technics...) so I was evaluating to setup a small differential circuitry, but first I wanted to double-check what is on the market. No problem on multiple pulses management because it's a house-gate opener impulse that doesn't need accuracy in pulse length. I think the edge-triggered relay is a great idea and can fit this application, now I search for one. @James: I think a PLC it's too much in complexity/cost, but thanks for the answer too.
Yes something simple in the budget. We are using this new line of products from Bticino brand where the push button is missing, only the multyway switch (great aestetics but poor technics...) so I was evaluating to setup a small differential circuitry, but first I wanted to double-check what is on the market. No problem on multiple pulses management because it's a house-gate opener impulse that doesn't need accuracy in pulse length. I think the edge-triggered relay is a great idea and can fit this application, now I search for one. @James: I think a PLC it's too much in complexity/cost, but thanks for the answer too.
As an alternative, perhaps you could take a standard Bticino switch mechanism and modify it to include a momentary contact? Or modify the 'click' mechanism or install a spring inside to return the original contact to the 'off' position? Modifications would invalidate the safety approval for electrical power usage, but if you are only operating an extra-low voltage trigger for the gate that might not be a problem.
it's not low voltage it's 230Vac, I found some candidates, but I think they only trigger at the rising edge not at the decreasing edge:
Also it seems that the input signal is a dc, and can't be the 230Vac, I think I need to build it up analogically.
Also it seems that the input signal is a dc, and can't be the 230Vac, I think I need to build it up analogically.
The circuit can be very simple if there is a suitable DC supply of a few milliamps available. Is there a 5, 12 or 24V DC supply on the unit e.g. for a radio receiver, that can be used for the pulse circuit? Can you build small electronic circuits on perforated board? It's going to need about 10 components.
I'm thinking a good old fashioned 555 would probably be suitable.
The trick I think the OP is looking for here is to trigger on both the opening and closing of the switch, so that you just flip it once to open the gate. The 555 is a useful collection of bits that can be assembled to do many things (including what it does best, short the supply rails together when changing state) but I can't immediately see how to make it respond to both switch edges without extra active components.
Does the switch range from Bticino include intermediate switches (4-terminal switches for lighting control with more than two switch positions?) If so, take a look at this possibility:
C needs to be large enough for the unit to reliably respond.
R1 might not be needed, depending on minimum pulse length and threshold voltage of the input. E.g. if the trigger current is much less than the short-circuit current, R1 can be used to extend the pulse available from a given capacitor size.
R2 is only a nicety to prevent the caps being dead shorted by the switch, R2C = 0.1 seconds.
Does the switch range from Bticino include intermediate switches (4-terminal switches for lighting control with more than two switch positions?) If so, take a look at this possibility:
C needs to be large enough for the unit to reliably respond.
R1 might not be needed, depending on minimum pulse length and threshold voltage of the input. E.g. if the trigger current is much less than the short-circuit current, R1 can be used to extend the pulse available from a given capacitor size.
R2 is only a nicety to prevent the caps being dead shorted by the switch, R2C = 0.1 seconds.
Must admit I didn't read the full detail of the question.
Using the above capacitor gadget to trigger a monostable (which could be implemented using a 555) would make the control circuit independent of the characteristics of the controller. Using passives only, the trigger input resistance and threshold are important, whereas if the monostable pulls solidly up or down it will work with any input. OTOH a transistor driving a relay might be even more universal still.
Here is my attempt at a differentiator or dual edge triggered detector. If I can find some mains rated opto coupled isolators in my man shed I will swap the red spst dip switch for a mains switch operating a lamp. This would be tomorrow though.
It uses three quad 2 input nand ics. I had to hand some 4011s.
?
It uses three quad 2 input nand ics. I had to hand some 4011s.
?
Excellent toolbox parts solution. I have in mind a single-package solution using an LM339 - a=input buffer, b=inverter, a couple of diodes and c + d=window detector.
I have to admit that many of my quick solutions these days are just PICs. As much as I like to design circuits, I can usually get there faster by programming. On one occasion I had so little time to make a gizmo to send abroad, I built the hardware and sent an in-circuit programming cable with it, then while it was in transit built a copy, programmed and debugged it and then sent the hex file for the end user to upload. At the moment of dispatch I hadn't actually worked out any of the logic or math, and there was quite a lot of floating point that I didn't have a hope of programming in time. By building generic hardware, I didn't need to think about it at that stage.
But I do like tricky hardware solutions. I am seeing an opto-isolator inside a bridge rectifier, maybe a unijunction transistor. How about a couple of ECC82s? What about triggering on the transit time of a C/O relay contact? Two mercury switches connected by a spring?
I have to admit that many of my quick solutions these days are just PICs. As much as I like to design circuits, I can usually get there faster by programming. On one occasion I had so little time to make a gizmo to send abroad, I built the hardware and sent an in-circuit programming cable with it, then while it was in transit built a copy, programmed and debugged it and then sent the hex file for the end user to upload. At the moment of dispatch I hadn't actually worked out any of the logic or math, and there was quite a lot of floating point that I didn't have a hope of programming in time. By building generic hardware, I didn't need to think about it at that stage.
But I do like tricky hardware solutions. I am seeing an opto-isolator inside a bridge rectifier, maybe a unijunction transistor. How about a couple of ECC82s? What about triggering on the transit time of a C/O relay contact? Two mercury switches connected by a spring?
What do you think of such acircuit:
where V1 represent the full rectified and buffered sinusoidal and R2 is a simple relay coil.
From simulation the lenght of the pulse of the coil is 0.5s, I hope it's enough, or the capacitor value will need to be even higher than 470uF.
where V1 represent the full rectified and buffered sinusoidal and R2 is a simple relay coil.
From simulation the lenght of the pulse of the coil is 0.5s, I hope it's enough, or the capacitor value will need to be even higher than 470uF.
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