Guest badai

detector prototype

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Guest badai

I want to design a detector to detect residual electricity power in the electrical appliances. As we know many of the electrical appliances consist capacitive and inductive inside it. My idea is using am receiver circuit (need some modification). Anyone have any idea to help me??......... ;D

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Guest badai

nice idea.......here i state what the my project objective

for many electrical appliances, although we have switched off the main switches, an amount of residual electricity power remains to be in the appliances as long as the wire is not unplugged. this phenemenon is because of the capacitive and inductive components inside many of the electrical appliances today......this is what i'm looking for to design the detector to detect the residual electricity power in any electrical appliances.....(related with EMI)
ex: when you use a handphone close with radio(tune radio), the radio will detect a noise what we call electromagnetic interference
so, is it suitable for this problem with the device you suggested to me???

can you explain more about the funtion this meter, so i can learn more about this.......



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Badai,
The Field Strength Meter is a simple untuned AM detector just like part of an AM radio. It is used to measure the radio-waves strength of a nearby radio transmitter. It might be sensitive enough to also detect nearby live mains wiring.
What do you expect to measure from an appliance that is not turned on? It might have "risidual" electricity that is stored in a charged capacitor, but that voltage is a steady DC without any electromagnetic radiation (radio-waves). The power in an inductor is dissipated within milliseconds after turning off the power. Motors that produce spinning magnetic fields and maybe sparking, have stopped and therefore no longer produce radiation.
You say that residual power remains in the appliance as long as the mains wire is not unplugged, which is true only if the appliance has continuous power, even when switched off, for a function requiring power like remote control or a clock.
You also say that a handphone (cell or wireless?) causes interference to a nearby radio, of course it will because it is an operating radio transmitter. A field strength meter will measure its radio-waves strength. The radio-waves (interference) stop when the handphone is turned off.
Good-luck with your detector of something that does not occur. As you can see from the links, perhaps you should change your objective to detecting active EMI.

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Guest badai

okay, i accept your comment......and it is true....actually i was assigned to do this project under my lecturer....below this i state what my lecturer looking for from this project......

Objective: (a) To study the residual power in the switch-off-but-unplugged electrical appliances.
(b) To design and to prepare a hardware prototype to detect the existence of the residual electricity power in the electrical appliances.
© To provide security as well as to help estimate the electricity bills that could be saved.
Description: This project requires one Final Year Project (FYP) undergraduate candidate.
The whole project involves both the theoretical studies and hardware prototype development.

For many electrical appliances, although we have swithed off the main switches, an amount of residual electricity power remains to be in the appliances as long as the wire is not unplugged. This phenomenon is because of the the capacitive and inductive components inside many of the electrical appliances today.

The FYP undergraduate candidate is expected to study this phenomenon and then to propose a hardware prototype to detect the residual electricity power in any electrical appliance. One is also required to estimate the electricity bills that we can save between the scenario of plugged and unplugged situations for various types of electrical appliances.

In case the time factor of this FYP allows, one is also required to study the security level of the switched-off-but-unplugged electrical appliances.
(*1st suggestion from my lecture is using am/fm receiver circuit)

i hope after read this, anyone know about this can give any comment about this either is it possible or not

so, maybe it will help me to decide what circuit will be used, then i can prepare for my hardware

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Badai,
Before you said that the appliances are switched-off and NOT unplugged from the mains. Now your objective says that they are switched-off-but-unplugged.
Are they plugged or not?
I think that your lecturer is crazy to believe that appliances can produce EMI when switched-off, regardless about whether they are plugged-in.
Good-luck, again.

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A detector will tell you how noisy an appliance is, but will not let you measure the power being consumed. You may be better off trying to find a non-invasive way of sensing the current through the power cord, though I suspect that will be difficult and you will have an easier time plugging the appliance into (through) a current monitoring device.

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Guest badai

my project must go on.......so now i'm using am/fm receiver circuit to design my hardware.....the problem now to there are too many circuit that i searched in internet......the important part to decide the frequency range.....my hardware is want to detect the noise from electrical appliances like motor, air-con, fan and etc. anyone can help????.............

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Badai,
You can build an EMI detector to prove to your crazy lecturer that only OPERATING appliances emit EMI, and maybe get bonus marks (or get expelled).
You need a very-low-frequency AM receiver circuit. A normal AM broadcast band receiver will pick-up a bit of EMI when tuned to a quiet spot between radio-stations near the low end of the dial. It will be much better if you can pick-up frequencies that are much lower than that.
Have you tried the simple Field Strength Meter circuit, but using a much bigger RFC (or 1K resistor) so that it picks-up lower frequencies?
Our Projects Section has an Electronic Eavesdropping Detector project that may be suitable if you use much bigger capacitors for C4 and C6 (marked D1 by mistake) so that it picks-up lower frequencies. The project is here:
http://www.electronics-lab.com/projects/rf/005/index.html
But if you have any near-by radio or TV stations then the above circuits will pick them up instead, since they are not tuned.

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This circuit will detect mains power and indicate this by the LED blinking at about 3 Hz for 50 Hz mains. The antenna is anything from 5 to 25 cm of wire depending on the sensitivity that is needed.

Ante ::)

post-929-14279141626524_thumb.gif

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Ante,
Your circuit has a very good use of the very high input impedance of a CMOS chip. Do you think that it works as a capacitor voltage divider, with its antenna as a plate of a capacitor between the mains voltage and ground?
Try it with an inverter as the input, which connects to a bunch of paralleled inverters that drive a speaker.

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[snip] ...only OPERATING appliances emit EMI... [snip]



Many of the newer appliances have things running even when the appliance is not in use. Most easily recognized is the clock, but some have other devices running caused by microprocessor circuits. In the case of these appliances, even unplugging them would allow the system to run on the back up memory for a small period. Perhaps this is where this "crazy" lecturer is going?

Although this makes no difference in most cases, if one is setting up a solar system for a house, these little draws on the system really add up from appliance to appliance. (Another point of interest)

I think we are sometimes quick to call someone crazy when we do not understand why they do what they do.

MP

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I said that already:



You say that residual power remains in the appliance as long as the mains wire is not unplugged, which is true only if the appliance has continuous power, even when switched off, for a function requiring power like remote control or a clock.
As you can see from the links, perhaps you should change your objective to detecting active EMI.

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i have refer back to my lecturer, he said for switched off electrical appliances, we may need UPS or transformer that have high residual electrical power because my project topic is flexible so it doesn't concentrate to certain device. then now, he want me to try at the beginning stage using mobile phone under this condition (on steadily, on transiently, off steadily and off transiently), so my idea now is using tune radio circuit(am/fm receiver circuit). so after that it can help me to use other appliances and improve my project to get better design. any comments??.......... :)

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Badai,
You may have a problem by using this project:



Our Projects Section has an Electronic Eavesdropping Detector project that may be suitable if you use much bigger capacitors for C4 and C6 (marked D1 by mistake) so that it picks-up lower frequencies.
But if you have any near-by radio or TV stations then the above circuits will pick them up instead, since they are not tuned.



An LM324 will replace the MC3403, and a 1N34A diode will work in this project.

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since my project cover in wide scope, then my supervisor want me to design the detector for detecting cellular phone only. nowadays, we find that some places like in hospital, aeroplane even in exam hall(to cheat) and etc. we does not allow to use the phone to avoid any problem. so, my detector suppose to detect when somebody using their phone in that area. as we know when the phone getting close with the radio, we can detect the noise. is it hard to design my hardware using the tune radio circuit or any possible circuit?

audioguru, in this website http://www.electronics-lab.com/projects/rf/005/index.html , can you explain what the number in circle for, and the pin 4 and 11 how to connect it?

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Badai,
The Eavesdropping Detector project might be sensitive enough to pick-up a nearby transmitting cell phone without tuning, if it isn't overloaded by nearby radio or TV stations.
If you could add some kind of tuning circuit to it, you won't know which cell frequency is used. Some cell phones use "spread spectrum technology" where the frequency continues to change.

The circled numbers on the schematic refer to connections that are external to the PCB, such as antenna, speaker and battery.
Pins 4 and 11 are the power supply pins for the IC, and are already connected on the PCB.

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i've few questions here:

1-some cell phones today using dual band and tri band type. is it make any effects on the circuit?
2-in my country(malaysia) we using some types of network: celcom(900MHz), adam(1800MHz),digi(1800MHz),maxis(900MHz) and tm touch(1800MHz), so can you explain how these operating frequencies is working with this circuit?
3-this circuit is operating on the range of 1-1000MHz frequency. then, let say i'm using digi network, could the circuit detect the cell phone?

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i learn that EMI will occur when these three elements exist, source of emission, coupling path and receptor. so, i'm using cell phone as a source of emission and tune radio as a receptor. anyone can explain about the coupling path under this condition?

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Hi Badai,
Have you built your detector yet?

A good coupling path is short, directionable and without obstacles. Antennas should have the same polarization (turn your AM radio around and hear the difference).
A poor coupling path is from here to the planet Pluto, with the Sun in between! (or with a shield around the source of EMI)

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