Hello, I was wondering if anyone in here might know how I might be able
to control an analog switch with a wireless button? I would like to
control a 4066 analog switch wirelessly. I'm looking for something
that would have real quick response time from whenever my button is
pressed, and the range doesn't have to be more than a few feet. I
don't know anything about wireless, but just seeing all the wireless
mouses, car alarms, toy cars...etc, makes me think that this might be
possible. I'm just not sure how to get started and where to look.
Unless you're looking for a learning experience, I'd suggest paging through a
magazine such as Nuts & Volts and just buying one of the many
transmitter/receiver combintations sold within. Most of the receivers with
have, e.g., 5V outputs that you can directly use to control your 4066.
Its actually not so much as a learning thing for me, I'm trying to
design something and if i could get a wireless button that would
activate a switch with virtually no time delay and the button be very
compact, and the reciever/transiever be very compact as well, it would
help me get my project done, but I'm not neccesarily trying to build
the wireless part myself. If there's something out there, already made
that can do this, thats what I'm looking for.
I don't know if what I want exist, but I need something where I can
hook up a button that is on momentarily when pressed to a transciever.
And that on the reciever end it enables a switch instanteously only
while the button is pushed. I need to be able to push the button
repeatedly very quickly and have the switch at the reciever end respond
without any noticable delay.
I can't find anything to indicate response time on these circuits at
this link. I think there is a little delay in a typical car door
opening wireless system, but am not sure.
Well, yes. There is, definitely, a little delay, caused by the
wireless part of the system. But you would probably have to measure it
in millionths of a second, or less.
The speed of light being what it is, the delay will also increase, the
farther apart the transmitter and receiver are.
How much delay can you tolerate?
Forget speed of light. Not an issue.
The delay is caused by a number of factors. The reciever might need to apply
AGC to the carrier before it can decode the data, then the reciever will
need to validate the data being sent (CRC or some such trick). The data rate
will also be a lot less than the 433mhz carrier frequency..
Hmmm... if the delay is around 1/10 of a second, that would probally be
fine. I just need to be able to tap the button as fast as I can with
my finger (5 or 6 times a second probally) and the switch turn on and
off along with my tapping, with no noticable delay.
What type of transciever/receiver stuff does this? Do you think the
one's in car alarms are fast enough? Do you know what is in the
These little RS ZIPZAP cars work very well. The receiver is tiney, and
has two outputs in an H-bridge configuration for forward-reverse, and
two open collector outputs for left-right steering. A little external
logic gives you a lot of control options. Adding more wire for the
receiver antenna really extends the range. I haven't done it, but you
could reduce the transmitter size by cutting up the xmtr PCB and getting
rid of the charger circuit.
I used one of these to remote control a gag gift for the departing
President of our college.
Because mechanical switches have contacts that don't just produce one
transition when you press them, they produce many - as the contacts
"bounce", or make several very short intermittent contacts before
finally reaching the desired state. These short intermittent contacts
may be as brief as a fraction of a thousandth of a second - but modern
electronics will respond to them as if you were tapping the button that
Now you don't want your gate to respond to these many intermittent
transition contacts - you just want it to respond to the first contact,
each time you press the button, so the system acts as if you have
pressed the button once, and not as if you had pressed it dozens of
times in the space of a thousandth of a second.
So "debounce" techniques are used.
One is to register the first contact but ignore any other changes for
the next, say, tenth of a second. That is long enough for the switch to
make final contact and so all the intermittent contacts within that
tenth of a second are ignored.
But, if you are pressing and releasing that button more than ten times a
second - the debounce circuit will also ignore your presses during the
tenth of a second after the first press...
So speed is an issue - if you are pressing and releasing the button
faster than the contacts have time to settle, then no "ignore" time will
do. Either the ignore time will be too long - and miss your presses, or
too short and include contact bounces.
There are alternatives though.
Such as having a "pressed" set of contacts and a "released" set of
contacts. When the button goes down, it makes the "press" contacts. When
the button comes up, it releases the "press" contacts, travels enough
distance to make sure that the "press" contacts are well and truly
seperated and then makes a set of "release" contacts.
When you press the button, the circuit responds to the first "press"
contact but ignores all the others as being bounces. When it gets a
"release" contact, it resets waiting for the next "press" contact and
ignores all the subsequent "release" contacts as also being bounces.
Such a circuit can respond to a train of button presses faster than a
simple "ignore" time delay.
Who would have thought something as simple as pressing a button could be
so complicated? However, it is, when electronics are connected to the
So that is why people are wondering why you want to press the button
repeatedly and what the whole project is about. It may then be possible
to suggest a simpler approach that doesn't need you to press the button
that frequently, or even at all..
Just wondering whether using a photo diode (or such) sitting behind a panel
might be a simple way of avoiding the switch bounce problem. In this case your
'button presssing' would actual be placing your finger over a hole in the panel
to change the light impinging on the photo diode/transistor.
Alternatively you could mock up a simple mechanical 'shutter' you press that
controlled the light falling on the diode/transistor
Even photosensors have a tendency to produce more than one transition
for each interruption. Unless designed not to, they can respond to the
changing reflection from fingerprint skin variations as your finger is
brought near the switching point. Similarly with a mechanical shutter,
particularly if there are multiple ambient light sources and especially
if they are ac-driven..
Such things are never quitre as easy as they first might appear..
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