Manchester decoding isn't as simple though, at least I couldn't find a simple sollution after a couple minutes of googling. Perhaps you'd care to share a simple clock/data decoding circuit from manchester Data? I'm curious as I'm going to want to use Manchester encoding at some point. Encoding is simple, no idea how to decode though.

__________________

 

Yes, that's my problem too.
For example, the data is 10010011 (start from the left), so the coded data should be: 1001011001011010. How does the microcontroller read this? How does the microcontroller know that which one is the start bit? Will the coded data be read like this:0100101100101101? (The 1st bit is 0)

Thanks

__________________
bananasiong

 

It doesn't, that seems to be the trouble with decoding manchester. A Preamble packet should solve that though. Known data allows you to figure out where the bit transistion occurs.

__________________

 

Why google?, why not just click on the link in my signature and look at my PIC tutorials?.

One of them implements Manchester coding/decoding - it's not my actual routines though, I got them off the net (and modifed them) - and as you say, it takes a LOT of finding.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Hi,
If I replace the oscillator transistor with 2N3663 or 2N5770, is there any problem? The purpose of doing this is because the transistor from the hobby kit is C9018 which is not available here.
And for the receiver, another transistor c945p, which I found that is just a general purpose npn transistor, so I can use 2N3904?
There is also a IC, kia567p. I think it is a phase lock loop and can be replaced by ne567n?
For the rfc at both transmitter and receiver, can I use 41uH instead of 1uH? I couldn't find it too.

Sorry, I can't find the schematic for the receiver yet, maybe I can't expect much without the schematic.

Thanks

__________________
bananasiong

 

You can't find the schematics and can't find the parts. Make something from a schematic and you can get the parts.

__________________
Uncle $crooge

 

How about the transmitter? I have the schematic but don't have the parts. Can I replace those components?
I think the c9018 is KTC9018, if I want to replace with another transistor, which rating between them should be the same? Is it the frequency? What about the value of rfc?

Thanks

__________________
bananasiong

 

If you change the transistor then the new one will have different capacitance and gain so the frequency and output level will be different. It looks like its frequency is not adjustable.
Try a different RFC, it will probably work.

__________________
Uncle $crooge

 

Yes, the frequency of the transmitter is not adjustable, the adjustment is being done on the receiver. Must the value of the rfc for both transmitter and receiver be consistent? They are the same for the original circuit, if I change for the transmitter, then I need to change for the receiver as well right?

Maybe I should start replacing a part followed by another part.

Thanks

__________________
bananasiong

 

The RFC doesn't affect the tuned frequency. Its inductive reactance is just a high impedance.

__________________
Uncle $crooge

 

Hi,
The schematic of the transmitter comes with the transmitter, but I found that on the schematic, the oscillator is made by NAND gate, but it is a HEF4001BP, a NOR gate. If it is a NOR gate, then should I change to pull one pin down?

Can I use normal logic gate such as 74ls00 or 74ls02 to do oscillation? I've tried with the same circuit, cannot.

Thanks

__________________
bananasiong

 

The output of a NAND gate goes high if an input goes low.
The output of a NOR gate goes low if an input goes high.

The modulating oscillator is for Cmos logic, not old TTL logic.

__________________
Uncle $crooge

 

Then I have to trust the internet that HEF4001BP is a NOR gate but not a NAND gate. I have wasted another PCB which has already been drilled and ready to solder..

__________________
bananasiong

 

A CD4011 or a HEF4011 is a Cmos quad NAND gate package. Its pins have the same layout as a 4001.

__________________
Uncle $crooge

 

Oh, then I can remain to use the design for NAND gate, thanks.

This is the receiver circuit that I've just done. The IC is LM567/NE567 phase lock loop.

This receiver circuit is designed for 12 volts, but I plan to use only 9 volts then I have to change to 9v relay. How about the zener diode?
From the schematic, I think when the signal is received, pin 8 of the phase lock loop gives a low, to turn the LED on and also the relay. If I don't want to use a relay, then I replace it with a resistor, and pin 8 to the microcontroller, can I?
I know the coil paralleled with the trimmer cap is to oscillate at 300MHz, but what's the purpose of the coil and the resistor at the antenna side? From the board, these coils are located near to each other.

Thanks

Attached Thumbnails

 

__________________
bananasiong