hi

I wish to make a wireless transmitter project with a range of about <=20cm

I only need to transmit 1 bit (1 or 0)
I have seen several projects on the net but they are too big and complex for my needs.

The transmitter needs to be very small (3 or 4 small components max)
It will have an input voltage of 6v when i want it to output 1 and 0v when it outputs 0

The reciever can be bigger and will be powered by 2 9v batteries. The reciever must be able to operate a relay when it recieves 1.


There will probably not be a direct line of sight between the two devices.

As an addition i want to allow several of these devices to operate near each other (within 2m) without them interfearing with each other.


Im not sure whether to use IR or RF or even ultrasound!
I really need to minimise the size of the transmitter.

I have done electronics for a few years but i thought id ask the experts before i buy the components.

Any help or suggestions are appreciated.
If anyone knows any good websites with relevant information or simialar projects i will be gratefull too.

Thanks

John

First, ir's out of the question, due to the line of sight issue. Second, will each be hardwired, probably with a set of switches, to be able to choose their transmission and receipt frequencies, or must they pick their own? Without choosing frequencies, as in they're all hardcoded, you're still going to need 3 of caps, and inductor, 2 resistors, an antenna, a diode, a transistor, and a 555 timer, unless you want to use an ic that's designed for such a purpose.

: hi
:
: I wish to make a wireless transmitter project with a range of about <=20cm
:
: I only need to transmit 1 bit (1 or 0)
: I have seen several projects on the net but they are too big and complex for my needs.
:
: The transmitter needs to be very small (3 or 4 small components max)
: It will have an input voltage of 6v when i want it to output 1 and 0v when it outputs 0
:
: The reciever can be bigger and will be powered by 2 9v batteries. The reciever must be able to operate a relay when it recieves 1.
:
:
: There will probably not be a direct line of sight between the two devices.
:
: As an addition i want to allow several of these devices to operate near each other (within 2m) without them interfearing with each other.
:
:
: Im not sure whether to use IR or RF or even ultrasound!
: I really need to minimise the size of the transmitter.
:
: I have done electronics for a few years but i thought id ask the experts before i buy the components.
:
: Any help or suggestions are appreciated.
: If anyone knows any good websites with relevant information or simialar projects i will be gratefull too.
:
: Thanks
:
: John
:

This message was edited by kor at 2003-7-30 8:40:11

---

Actually, I recently found out about hartely oscillators, much like a colpitts oscillators, that will do what you want quite nicely, and you may be able to get away without an amp. All you need is a cap, a tapped inductor, a transistor, and an antenna.

: First, ir's out of the question, due to the line of sight issue. Second, will each be hardwired, probably with a set of switches, to be able to choose their transmission and receipt frequencies, or must they pick their own? Without choosing frequencies, as in they're all hardcoded, you're still going to need 3 of caps, and inductor, 2 resistors, an antenna, a diode, a transistor, and a 555 timer, unless you want to use an ic that's designed for such a purpose.
:
: : hi
: :
: : I wish to make a wireless transmitter project with a range of about <=20cm
: :
: : I only need to transmit 1 bit (1 or 0)
: : I have seen several projects on the net but they are too big and complex for my needs.
: :
: : The transmitter needs to be very small (3 or 4 small components max)
: : It will have an input voltage of 6v when i want it to output 1 and 0v when it outputs 0
: :
: : The reciever can be bigger and will be powered by 2 9v batteries. The reciever must be able to operate a relay when it recieves 1.
: :
: :
: : There will probably not be a direct line of sight between the two devices.
: :
: : As an addition i want to allow several of these devices to operate near each other (within 2m) without them interfearing with each other.
: :
: :
: : Im not sure whether to use IR or RF or even ultrasound!
: : I really need to minimise the size of the transmitter.
: :
: : I have done electronics for a few years but i thought id ask the experts before i buy the components.
: :
: : Any help or suggestions are appreciated.
: : If anyone knows any good websites with relevant information or simialar projects i will be gratefull too.
: :
: : Thanks
: :
: : John
: :
:
:

Thanks for the help, ie scrapped the wireless bit for the moment, its too complicated. Ill try and build that in later.










: This message was edited by kor at 2003-7-30 8:40:11

---

: Actually, I recently found out about hartely oscillators, much like a colpitts oscillators, that will do what you want quite nicely, and you may be able to get away without an amp. All you need is a cap, a tapped inductor, a transistor, and an antenna.
:
: : First, ir's out of the question, due to the line of sight issue. Second, will each be hardwired, probably with a set of switches, to be able to choose their transmission and receipt frequencies, or must they pick their own? Without choosing frequencies, as in they're all hardcoded, you're still going to need 3 of caps, and inductor, 2 resistors, an antenna, a diode, a transistor, and a 555 timer, unless you want to use an ic that's designed for such a purpose.
: :
: : : hi
: : :
: : : I wish to make a wireless transmitter project with a range of about <=20cm
: : :
: : : I only need to transmit 1 bit (1 or 0)
: : : I have seen several projects on the net but they are too big and complex for my needs.
: : :
: : : The transmitter needs to be very small (3 or 4 small components max)
: : : It will have an input voltage of 6v when i want it to output 1 and 0v when it outputs 0
: : :
: : : The reciever can be bigger and will be powered by 2 9v batteries. The reciever must be able to operate a relay when it recieves 1.
: : :
: : :
: : : There will probably not be a direct line of sight between the two devices.
: : :
: : : As an addition i want to allow several of these devices to operate near each other (within 2m) without them interfearing with each other.
: : :
: : :
: : : Im not sure whether to use IR or RF or even ultrasound!
: : : I really need to minimise the size of the transmitter.
: : :
: : : I have done electronics for a few years but i thought id ask the experts before i buy the components.
: : :
: : : Any help or suggestions are appreciated.
: : : If anyone knows any good websites with relevant information or simialar projects i will be gratefull too.
: : :
: : : Thanks
: : :
: : : John
: : :
: :
: :
:
:
:
:

: hi
:
: I wish to make a wireless transmitter project with a range of about <=20cm
:
: I only need to transmit 1 bit (1 or 0)
: I have seen several projects on the net but they are too big and complex for my needs.
:
: The transmitter needs to be very small (3 or 4 small components max)
: It will have an input voltage of 6v when i want it to output 1 and 0v when it outputs 0
:
: The reciever can be bigger and will be powered by 2 9v batteries. The reciever must be able to operate a relay when it recieves 1.
:
:
: There will probably not be a direct line of sight between the two devices.
:
: As an addition i want to allow several of these devices to operate near each other (within 2m) without them interfearing with each other.
:
:
: Im not sure whether to use IR or RF or even ultrasound!
: I really need to minimise the size of the transmitter.
:
: I have done electronics for a few years but i thought id ask the experts before i buy the components.
:
: Any help or suggestions are appreciated.
: If anyone knows any good websites with relevant information or simialar projects i will be gratefull too.
:
: Thanks
:
: John
: hi, I go out on a limb, because the wireless issue altogether isn't defined if it's an electromagnetic radiation that has had a higher frequency carrier to get it to the receiver to then have the intended message extracted or it is like an arc lamp or an infrared beam that streams to its intended reciever. Tranmitting a pulse, which is actually about 4.7 volts to signify a 1 has traditionally been done by capitance, like a microphone that amplifies the voice so it travels louder and quicker. But distant doen't seem to be a factor. The generality may lie in the remote control, or garage door opener ideology. Sending a pulse to trip a switch, show a flag, is an algorithm to indicate the status of a process. Getting a response to the source of the pulse is the inverse of the function. y = f(x), then x =f(y). It's unfortunate that many have to grind through advanced signal analysis to try to achieve a basic task. dpghost

: hi
:
: I wish to make a wireless transmitter project with a range of about <=20cm
:
: I only need to transmit 1 bit (1 or 0)
: I have seen several projects on the net but they are too big and complex for my needs.
:
: The transmitter needs to be very small (3 or 4 small components max)
: It will have an input voltage of 6v when i want it to output 1 and 0v when it outputs 0
:
: The reciever can be bigger and will be powered by 2 9v batteries. The reciever must be able to operate a relay when it recieves 1.
:
:
: There will probably not be a direct line of sight between the two devices.
:
: As an addition i want to allow several of these devices to operate near each other (within 2m) without them interfearing with each other.
:
:
: Im not sure whether to use IR or RF or even ultrasound!
: I really need to minimise the size of the transmitter.
:
: I have done electronics for a few years but i thought id ask the experts before i buy the components.
:
: Any help or suggestions are appreciated.
: If anyone knows any good websites with relevant information or simialar projects i will be gratefull too.
:
: Thanks
:
: John
:

check out the ir tutorials on boondog.com ive made both and i can verify that it works. you should base your project on the short range ir that can be used for incremental encoders. the distance of transmitter and receiver can depend on the type of ir transmitter used and also the transistor configuration that would amplify the signal to your ir transmitter. for the output of the receiver you can condition the output signal by using a schmitt trigger and amplify the 5v to 6v that would drive the relay circuit by using a common emmitter amplifier using transistor of course you can use a 2n2222. dont forget the diode at your relay circuit. you can get a simple relay circuit from other electronic sites. if youre good in your pcb arwork you can cramp the pcb's in less than 2inch by 2 inch.

: check out the ir tutorials on boondog.com ive made both and i can verify that it works. you should base your project on the short range ir that can be used for incremental encoders. the distance of transmitter and receiver can depend on the type of ir transmitter used and also the transistor configuration that would amplify the signal to your ir transmitter. for the output of the receiver you can condition the output signal by using a schmitt trigger and amplify the 5v to 6v that would drive the relay circuit by using a common emmitter amplifier using transistor of course you can use a 2n2222. dont forget the diode at your relay circuit. you can get a simple relay circuit from other electronic sites. if youre good in your pcb arwork you can cramp the pcb's in less than 2inch by 2 inch.
:
:
IR requires line of sight, which was not guaranteed.