The wires must be in series in order to make a loop that has multiple turns.

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Uncle $crooge

 

i thought the CAT has many wires inside, and connect them to the output of 555 as shown in figure below :roll:

Attached Images

555_267.jpg (9.8 KB, 44 views)

 

No, that wouldn't help, wire it so they are all in series, effectively giving a number of turns to the coil.

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sorry, i really don't get it. if i connect them in series, that means there is only one wire connect from the output to the GND. can u show me in picture?

 

Connect the wires in the cable in series, then the magnetic field from the cable is increased.

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loop_of_wires.png (8.2 KB, 40 views)

__________________
Uncle $crooge

 

thanks!! i understand already. :wink: so i can use only the single core wire to turn for a few round, right?
sorry for my poor understanding.

 

yes u can ..but.. as already suggested it would be better to use the cat5 since it has many lines inside (just connect then to become a loop) , rather than using multiple loops of single core

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"Give a man a fish, and he will eat for a day. Teach that man to fish, and he will eat for a lifetime."

 

okay, thanks i will try to find the CAT 5 cable. if i can't find it, i will use my own way :wink:

the CAT 5 can drive how many watt?

 

Telephone cable is available with many wires, use it if you can't find CAT 5 cable.
Wire is rated in AMPS, not in WATTS. 200mA is very low and just about any reasonable wire size can pass it.

__________________
Uncle $crooge

 

oh.. i found the CAT5 already, actually is CAT6 (that's what available at my place). can i connect as shown in below? just a little bit different.

Attached Images

555.PNG (2.6 KB, 6 views)

 

NO! - that will cancel itself out, wire it as you've already been shown!.

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

 

oh! luckily u told me, otherwise i will wire them like what i thought can be done. thanks!

 

Your sketch is missing the current-limiting resistor that should be in series with the loop of wire. The 555 will melt without the resistor because its max current rating is only 200mA, and a loop of wire could be a dead short to it.

__________________
Uncle $crooge

 

yup, i have forgotten to include it.. hehe.
the 555 timer will melt!?!? i didn't know that, it is so serious!! but i will remain the 100R to limit the current, in case the wire cannot support it. since the multiple loop can increase the electromagnetic field

 

hi all,
i'm going to do presentation with this circuit 2 weeks later. if anything goes wrong, correct me ok?

The 555 timer produces a 10kHz(approximately) squarewave output at pin 3 with the combination of R1, R2 and C1. The 'antenna' will produce electromagnetic field on and off in 10kHz.

the resonant frequency of the tank circuit is 10kHz. the 100K resistor creates a gain of a few hundred thousand which is so high that it probably amplifies its own noise and any noise that is around. It might even oscillate.
If a 0.1uF capacitor is added to ground at pin 3 then it won't oscillate. When the signal is received then the output of the receiver should alternate between 0V and Vcc at the frequency of the input. With a 5V supply then the output's min current of only 6mA should be able to saturate good with 5mA from a 1k load.

are these correct? i copied them from urs explaination. is there anything to be explained with this circuit?

edit:
1. what is the purpose of the 0.01uF capacitor from pin5 to GND of the 555?
2. why the 0.1uF capacitor from pin3 to GND at the LM393 can stop it to amplify other noise and its own noise and stop oscilating?
3. what's the different between a comparator and operational amplifier? can a comparator be an op-amp and vice versa?

thanks for helping..

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a.PNG (18.5 KB, 159 views)