I’m new to this forum and electronics so this might be a pretty dumb question. How can I reset a timer (I’m using a 555 timer and a 4017 decade counter) wirelessly using a RF link Transmitter-434MHz and a RF Link 2400bps Receiver-434MHz from SFE(http://www.sparkfun.com/products/8945 this is for the transmitter). I also do not want to sue microcontrollers.
Thanks
Sorry, I spelled use wrong. I did not intend to sue microcontrollers.
I can’t use encoders and decoders either but can I use a 555 timer?
BTW I need answers ASAP, it’s for a school project
Also, can I use a 555 timer to encode and a 567 to decode? If so, how do I do it?Do I use the 555 timer as an astable multivibrator?
Welcome to these boards!
Unfortunately, simple wireless modules like what you have suggested are not useful without additional error detection / correction. Otherwise, you will constantly trigger when you’re not transmitting. Normally, you would use microcontrollers for this, and I encourage you to explore PIC or Atmel microcontrollers (or PICAXE / Arduino or similar).
If you really don’t want to use microcontrollers, try encoder / decoder chips like the RF803, which are often used in garage remote control and similar applications.
BTW, that transmitter is 315MHz, not 434MHz. Obviously, the transmitter and receiver have to be on the same frequency.
Why can't you use encoders / decoders? You can't really use just a 555 to encode a datastream (as it would just give you a squarewave), but you could re-create one I guess with some other circuitry. At the end of the day you'd spend a bunch of time to achieve something a $1.50 encoder / decoder chip could do...The Kid:
I can’t use encoders and decoders either but can I use a 555 timer?
I tested my circuits using LEDs and a switch but the receiver doesn’t receive anything! What’s wrong?
BTW: My transmitter and receiver are on the same frequency. Sorry for the wrong link!
If I use a 555 timer to encode, do I have to use a 567 to decode(found it on another site)? And does it have to be a certain frequency?
Also, I found a keyboard encoder/decoder; a 1 to 8, 3 to 8, and 1 to 16 decoder/demux at my local electronics store(http://www.active123.com) and a 3 to 8 encoder at my school. Will they work?
use a holtek HT12E (encoder) on the transmit side and
a holtek HT12D (decoder) on the RX side.
These are easy to use, and 100% reliable.
The data sheet is straight forward and will have an example schematic diagram to follow.
If you need help with these holtek devices, many here will be able to help you.
Hi newbie123,
I saw the datasheet of the chips and they look pretty awesome but where can I get one? I live in Canada and my project is due on the tenth so I need a source that ships quickly.
PS: I’m also tight on allowance so I need a source that charges low for shipping.
To all that are posting on this thread:
I’m a newbie so if you want to explain an idea, please post a schematic or a very detailed description.
Your help is very appreciated,
The Kid
I tested this circuit again.The Kid:
I tested my circuits using LEDs and a switch but the receiver doesn’t receive anything! What’s wrong?
Can I get some help on this?
The Kid:
I tested this circuit again.The Kid:
I tested my circuits using LEDs and a switch but the receiver doesn’t receive anything! What’s wrong?Can I get some help on this?
We’ve been giving you help (i.e. suggestions). We’re doing this for free because we’re intereted in this stuff, but don’t expect us to do all the work for you.
As per previous suggestions, you need to use encoder / decoder chips, or use a microcontroller to do the same thing. Otherwise, the receiver will likely just go high and low randomly as it looks for a signal.
Newark Canada has the suggested Holtek parts in stock:
Thanks for the Web links :D :D :D . But the receiver doesn't go high, much less going randomly. Is there an explanation to this or is it because my receiver/transmitter is broken? Is it just because the pulses are to quick to be noticed? Am I answering my own questions? :?: :?:MichaelN:
Otherwise, the receiver will likely just go high and low randomly as it looks for a signal.
Great news! My mom let me use arduino for my project. Other than the transmitter/receiver and the arduino, do I need other external components? Since I do not have any experience with microcontrollers, how will I program it? Is it easy to learn and make?
Sorry, I just noticed your schematic. You’ll never get any light out of that LED the way that the transistor is connected. If you give a link to the receiver you’re using I can suggest how you should be connecting it.
http://www.sparkfun.com/products/8949 here it is. I also did some research and found this website:http://www.rentron.com/rf_remote_control.htm. In the driving relays section it’s almost exactly the same thing as my schematic but I omitted the relay because aren’t relays and transistors almost the same thing? I also tried without a transistor but still no flash.
BTW I see RX TX pins on Arduino but how will I do it with a PICAXE 08M? And is Arduino/BASIC hard to learn for an 8th grader?
This is how I’d suggest connecting the LED to the receiver (image modified from the receiver datasheet):
http://users.adam.com.au/mnoble/Wireless_LED.JPG
As for the Arduino / PICAXE, if you’re prepared to spend the time to learn and read instructions you should be able to use either. If you need to do this in a hurry, and you haven’t previously programmed microcontrollers, you’d be better of using encoder / decoder chips such as the Holtek types previously discussed.
So I guess I’ll stick with either PICAXE(because I know a lot of people who can help me w/ BASIC) or encoder/decoders.
I have a schematic that I’m using for the LEDs.I guess I can put where the LED’s cathode is to the timer’s reset pin.
This is my final schematic.
