why must the output of the 555 timer (after the 100R) be connected to the GND (-ve terminal of the battery)? can i connect it to nothing? as an antenna..
I think he's asking if the loop will work without grounding the other end, and I think the answer is, not very well. He could tweak the series resistor (100 ohms) to adjust the sensitivity, once he starts to test it. If it works without the GND, so much the better. He did say he wants less than 10cm range.
I think he's asking if the loop will work without grounding the other end, and I think the answer is, not very well. He could tweak the series resistor (100 ohms) to adjust the sensitivity, once he starts to test it. If it works without the GND, so much the better. He did say he wants less than 10cm range.
Thanks.. Ron H... so u mean... it is better if i don't ground the other end of the antenna.. right? what about the 100R? can it make the range of the detection between the antenna and the receiver less than 10cm?
I think he's asking if the loop will work without grounding the other end, and I think the answer is, not very well. He could tweak the series resistor (100 ohms) to adjust the sensitivity, once he starts to test it. If it works without the GND, so much the better. He did say he wants less than 10cm range.
Thanks.. Ron H... so u mean... it is better if i don't ground the other end of the antenna.. right? what about the 100R? can it make the range of the detection between the antenna and the receiver less than 10cm?
No I definitely did not say that. I thought I was pretty clear.
It might work not grounded. It has a better chance of working if it's grounded. Try it both ways. If it works when not grounded, use it that way. It will save power.
why must the output of the 555 timer (after the 100R) be connected to the GND (-ve terminal of the battery)? can i connect it to nothing? as an antenna..
The output of the 555 timer is the output of the signal generated by the 555 timer.
Connecting a pull-up or a pull-down resistor with a very low value is IMO a bad idea, because current can be wasted that way.
Why not just add a transistor FM transmitter circuit and connect it's "Signal In" to pin 3?
An FM transmitter is also available from antoons Page. See the url that someone posted above as part of their answer.
Connecting a pull-up or a pull-down resistor with a very low value is IMO a bad idea, because current can be wasted that way.
Why not just add a transistor FM transmitter circuit and connect it's "Signal In" to pin 3?
An FM transmitter is also available from antoons Page. See the url that someone posted above as part of their answer.
Connecting a pull-up or a pull-down resistor with a very low value is IMO a bad idea, because current can be wasted that way.
Why not just add a transistor FM transmitter circuit and connect it's "Signal In" to pin 3?
An FM transmitter is also available from antoons Page. See the url that someone posted above as part of their answer.
haa.. yea.. we are talking about the 555 timer as a signal and transmitter but not only the signal.. am i right, akg?
i've already tried this circuit, and it gives response!! but i still need to troubleshoot to get the right frequency and range.. thanks for ur help..
the transmitting frequency is calculated by 1.44/(Ra+2Rb)*C right?
then how about the receiving frequency? is it f = 1/(2*pi*sqr(l*c)) ? by calculating the LC circuit? must these 2 frequencies be the same?
the transmitting frequency is calculated by 1.44/(Ra+2Rb)*C right?
then how about the receiving frequency? is it f = 1/(2*pi*sqr(l*c)) ? by calculating the LC circuit? must these 2 frequencies be the same?
the transmitting frequency is calculated by 1.44/(Ra+2Rb)*C right?
then how about the receiving frequency? is it f = 1/(2*pi*sqr(l*c)) ? by calculating the LC circuit? must these 2 frequencies be the same?
thanks ya... can i know.. if i construct the circuit like what mstechca said.. can it be done? i mean from the transmitter circuit. can i use the same value of LC as in the receiver part so that i get the accurate tx and rx frequency? i just want to know what is going on.. thanks!!
thanks ya... can i know.. if i construct the circuit like what mstechca said.. can it be done? i mean from the transmitter circuit. can i use the same value of LC as in the receiver part so that i get the accurate tx and rx frequency? i just want to know what is going on.. thanks!!
any attention? :lol:
If my answers can generate some success, why not?
But anyways, that LC circuit I designed is intended to prevent newbies from creating shorts (unless of course the antenna is connected to +ve).
The LC network alone without the coupling capacitor, and without the antenna is the LC network used in EVERY radio, unless it has a crystal.
the LC network primarily determines the frequency of the signal. There may be other components in a transmitter that could affect the frequency as well.
As for accuracy, your best bet is to use two trim capacitors for C, one being a small range (for fine tuning), and one being a larger range (for coarse tuning, like adjusting a few dozen megahertz at a time)
u can use low feq , but higher the freq the transmission efficiency and also the voltage induced in the receiver coil will increase.the normal o/p of the ckt is low, when receiving signal , it will give that freq as the o/p
Because you were posting complete rubbish, with no relevence to the posted circuit - and with (obviously) not the faintest idea of how it was supposed to work! (as with most of your posts?).
u can use low feq , but higher the freq the transmission efficiency and also the voltage induced in the receiver coil will increase.the normal o/p of the ckt is low, when receiving signal , it will give that freq as the o/p
The coil is, the system is more a magnetic field system than an RF system, similar to the inductive loop hearing aid systems installed in Post Offices etc.
A parallel tuned circuit is a very high impedance at its tuned frequency. The output impedance of a 555 is a very low impedance and shorts the tuned circuit at the tuned frequency.
Quote audioguru: Posted: Sun Mar 12, 2006 10:59 pm
"A tank circuit is a high impedance parallel resonant circuit. It should be driven from the very high impedance of the collector of a transistor, not the very low impedance output of a 555 where it won't do anything.
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Uncle $crooge"
i've tried this circuit, and i connected a LED to the pin 1 of the op-amp and ground to the cathode of the LED. when there is no signal, the LED is high.