Building a Simple Remote-Controlled Switch

[jbord39]

Hey all,

I am trying to make a simple remote controlled switch (without any digital IC's) and was wondering if anyone knew of any schematics, etc.

Thanks,

John

 

[berkeman]

Hey all,

I am trying to make a simple remote controlled switch (without any digital IC's) and was wondering if anyone knew of any schematics, etc.

Thanks,

John

Remote controlled via RF, or IR, or laser pointer, or... ?

What is the range? What is the target device?

 

[jbord39]

A radio frequency control. The range would preferably be 100+ yards.

 

[vk6kro]

If you can use it at 100 yards with a simple receiver, it would be detectable at several miles with sensitive receivers.
So, you would need to be operating it in a designated radio control band and it needs to be properly designed for minimum interference to other frequencies.

The easy way would be to visit a toy store and look for a cheap toy with remote control in it. Then remove the electronics from it and use that for your project. I have seen toys for less than $10 that had remote controls in them.

Make sure you photograph it before you wreck it, and make drawings of where all the wires go.

Or, you could just play with the toy. Some of these things are so beautifully made it seems sad to wreck them.

 

[jbord39]

Thanks. Do you know of any actual schematics? I do not want to just move around parts but rather build one from scratch.

 

[vk6kro]

I would have to look around for some, just like you can.

At the top of this page, you will see some links to sites that have a lot of electronic circuits.
See: Useful EE Links and Search Engines

However some of these probably use digital circuits. These have been around for 40 years, so you need to get used to using them.

I don't see much difference between copying someone else's circuit and just buying a circuit already built, except it is probably cheaper to get it already built.

 

[jbord39]

Well I do not want to copy someone elses circuit but using examples is certainly helpful. Since I am doing this to learn about RF in some way it seems silly to buy one already built.

 

[berkeman]

Well I do not want to copy someone elses circuit but using examples is certainly helpful. Since I am doing this to learn about RF in some way it seems silly to buy one already built.

That is good motivation, but please keep this in mind -- if you mess up your RF transmitter, even a little, you can cause harmful interference to other users of the RF spectrum. This is not only obnoxious and sometimes dangerous, it is illegal. That is a reason to use a pre-made RF transmitter, until you have the knowledge and test equipment to be able to make your own legal and safe transmitters.

For example, if your transmitter does not meet the skirt requirements and the harmonic content requirements of the FCC, you may end up splattering interference into police, Fire and EMS bands. You will garner a lot of attention if you do that, and the end result will not be good. (Not to mention that you could interfere with life-safety calls. Not good.)

So for now, please use pre-made (and FCC approved) transmitters, and focus on building your own receivers from scratch. As you learn more, and get familiar with using more complex RF test equipment (like spectrum analyzers, etc.), then you may be in a position to start building and testing your own transmitters.

As you can tell by vk6kro's username, and my signature, you can also learn a tremendous amount by getting your Amateur Radio license (HAM license), and starting to learn about TX/RX circuits in the Amateur bands. There are a lot of fun projects that HAMs build and use, including remote control, TV links, digital "packet" links, and so on. Consider contacting the HAM group in your area to talk about the projects that they have been working on. You might just find some great mentors and learning resources.

 

[vk6kro]

There is a way to be legal with this. It may not be legal in all countries, though, so you would have to check.

There is a small band of frequencies around 433 MHz which is sometimes allocated for short range projects like garage door openers.

You can get small modules that can be connected up simply and these give reasonable range, depending on the antenna used.

Have a look at the following site:
http://www.rentron.com/rf_remote_control.htm
and this one:
http://www.rentron.com/remote_control/remote1.htm
to get an idea of how these things are used.

These modules are ready-built but they avoid the need for you to have thousands of dollars worth of test equipment needed to construct and adjust them yourself.

 

[jbord39]

Thanks for the help I am looking into those now.