Need help creating cellphone mute

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Equinox2355
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Need help creating cellphone mute

Post by Equinox2355 » Sun Jun 20, 2004 4:33 pm

Ive done some research and ive found out that I can use the cellphone mute function of my aftermarket stereo, all i need to find out is how to set it up in a way that a circit can detect the cellphone signal, and mute the radio. Now i know that to make it mute it needs to be grounded, but i saw somewhere else to put a 147-ohm series resistor in there to make it work. Any ideas would be greatly appreciated. Thank you<p>-Mike

Mike
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Re: Need help creating cellphone mute

Post by Mike » Sun Jun 20, 2004 5:15 pm

are you saying that you want the cellphone signal to activate the mute? thats not how they work. they are designed so that when a call comes through, all you need to do is press a button and it mutes.<p>a cellphone is always sending out and recieving a signal so it wouldn't work.<p>-Mike

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Re: Need help creating cellphone mute

Post by Equinox2355 » Sun Jun 20, 2004 5:27 pm

I know there has to be a way because there are cell phone holders that flash when you get a call, because it picks up a certain cell phone signal. What I need is a way to have a device that will detect the signal much like the cell phone holders and ground the wire with or without that resistor.<p>-Mike

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Re: Need help creating cellphone mute

Post by dyarker » Sun Jun 20, 2004 8:13 pm

With the info you've given so far, Mike is correct.<p>If you mean cordless phone, or cell phone with maybe a Blue Tooth link to a base, then something can be done. Like a photo transistor mounted over the LED on the base.
Dale Y

Equinox2355
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Re: Need help creating cellphone mute

Post by Equinox2355 » Mon Jun 21, 2004 10:51 am

well im not sure you guys are understanding me, below is a link to a product that detects cellphone signal and makes lights go off.
http://www.cellphoneshop.net/fluncephhoad.html i need a circuit like that that will detect it but instead of lighting up LEDs ground a wire (or ground it with a resistor)<p>-Mike

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Re: Need help creating cellphone mute

Post by Equinox2355 » Mon Jun 21, 2004 11:08 am

I forgot that it also needs to run off of 12VDC for a car

myp71
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Re: Need help creating cellphone mute

Post by myp71 » Mon Jun 21, 2004 11:44 am

Then you should Buy that cell phone holder and do what Dale Y said. That would be the easy way to do it. :) <p>My-p71

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Dave Dixon
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Re: Need help creating cellphone mute

Post by Dave Dixon » Mon Jun 21, 2004 11:49 am

My-P71,
Wouldn't you need a latch circuit as well?
Otherwise I would expect the mute to only happen
intermittently with the ringing/flashing. Some
sort of reset switch would be required as well.
That's if I understand the thread correctly.
Later,
Dave

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jwax
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Re: Need help creating cellphone mute

Post by jwax » Mon Jun 21, 2004 6:31 pm

I say buy it, Eq! Hey! "HOL-FLAUNIRegular price: US$43.99Sale price: US$7.90", you not only get the device you need, you get to tell us how it works! It may just have a microphone/amp/rectifier driving the lamp, with power borrowed from the cradled phone.
We'd like to know! :D

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Re: Need help creating cellphone mute

Post by dyarker » Mon Jun 21, 2004 6:37 pm

That holder probably gets a signal from the contacts on the bottom of the cell phone, or a microphone, or a vibration sensor; any would require the phone to be in the holder. Must work well, price reduced from $44 to $8! :p <p>To do what you want would amount to building a receive only cell base station that listens for the digital signaling from your cell phone.<p>Cheers,<p>[ typing same time as jwax ]<p>[ June 21, 2004: Message edited by: Dale Y ]</p>
Dale Y

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Edd
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Re: Need help creating cellphone mute

Post by Edd » Mon Jun 21, 2004 6:46 pm

Solar/Lunar Equinox:<p>I’m assuming that this is for mobile
installation. So initially you need to try that mute interconnect point on the system and see/confirm exactly what value of shunt resistor to ground is needed. Initially, take your specified 147 ohm value and confirm that it actually works on muting the system when brought to ground level.
Then it would be a matter of then constructing a circuit for detection of a cellular incoming NAM handshake signal:<p>http://www.techlib.com/electronics/cellhelp.htm<p>Two options of circuitry given here, if using the first circuit, start with a value of ~1 ufd paper[no electrolytyics] on the gate of the VN10 to ground added to that circuit to establish enough on-hang time between NAM queries.
If you opt for the preferred second circuit, the 4401’s collector circuitry would perform the mute function grounding for you, pending proper circuit to circuit voltage isolation. If that should present a problem then insert a reed relay from 12v to the 4401’s collector, with coil shunt damping diode, and use its isolated reed relay to do the mute switching function.
F.I.O…At cell freq’s a sampling ¼ wave antenna stub wire would be in the order of 3.5 inches.<p>73's de Edd
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;) ;)<p>[ June 21, 2004: Message edited by: Edd Whatley ]</p>

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Re: Need help creating cellphone mute

Post by Equinox2355 » Tue Jun 22, 2004 8:48 am

Thank you Edd you seem to be the only one that really understood what i ment and how the device detected it. I was getting a little frustrated but i figured someone would know. This is exactly the curcuit i needed. Also do you know if it runs off of 12 volts and if it doesnt where i could get the diagram for a converter to bring it to the correct voltage needed for those cell phone signal detectors? Thank you again Edd, you saved me.<p>-Mike

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Re: Need help creating cellphone mute

Post by myp71 » Tue Jun 22, 2004 9:18 am

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by Dave Dixon:
My-P71,
Wouldn't you need a latch circuit as well?
Otherwise I would expect the mute to only happen
intermittently with the ringing/flashing. Some
sort of reset switch would be required as well.
That's if I understand the thread correctly.
Later,
Dave
<hr></blockquote><p>Oh, Yeah you would need a latch circuit and/or something to run the photo transistor.You really can't just put hook it up like a swich without somekind of control circuit.The photo transistor changes the resistance across the leads when it's dark or light.<p>Hope that helps a little bit<p>My-p71 :cool:

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Edd
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Re: Need help creating cellphone mute

Post by Edd » Tue Jun 22, 2004 10:26 am

On the second circuit with its more commonly available parts you will find it using a 12VDC supply. Personally I would triple filter that supply line, e.g. supplementing that sole 1ufd line filtering capacitor with an additional shunt 470 ufd as well as a short lead .1ufd disc ceramic, considering the RFI encountered in modern day autos.
On the first circuit , [unless you are an avid experimenter with a well filled junque box],it may be harder to find that LM10 ultra low voltage/low power amp as well as the TO-92 encased VN10 FET. Multiple options to get 9VDC , just a series dropping resistor from the 12VDC and then to a 1W 9V zener diode and electrolytic cap filtering by the existant electrolytic in the circuitry.Or use a 3 term regulator LM7809 or a 7805 and use the old trick of setting its gnd terminal up from gnd via a zener diode or even a resistor into fool it into giving more than its spec of 5VDC.Lastly , a waste, but use an adjustable LM317.<p>73's de Edd
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Re: Need help creating cellphone mute

Post by ng2aradiofunk » Mon Jul 19, 2004 5:06 pm

Useful Links..Thanks<p> <a href="http://www.cellphoneshop.net/fluncephhoad.html" target="_blank">http://www.cellphoneshop.net/fluncephhoad.html -
Deep Discounted Cell Phones and Accessories
</a><p>Ref'd here: $7.90 Flashing Universal Cell Phone Holder<p>Equinox2355
New Member
Member # 1989 <p>
http://www.techlib.com
<p>Edd Whatley
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