Hi All,
Just wants to experiment. I had a spare cellphone boom handsfree laying around. Tried to connect the earphone part to earphone socket of laptop with wires, it worked. But did't work for microphone part . I just heard noise if I used sndrec32.exe to try it.
May be it was just an impedance mismatched between handsfree mike with laptop mike socket. Appreciate if some nice person in this forum shows me how to make it work. Do I need a circuit to bridge the mike and the socket. What kind of circuit it is if it needs.
Thanks in advance.
I dunno much abt such things, but could u try the mic on another stuff, like a stereo for example? You could then check if the mic itself isn't working. If it's, maybe you should measure current flow, then use a normal mic on ur laptop and check if there's any difference...
Sorry for not so detail to described.
FYI, the laptop has one socket for earphone/external speaker and one other for microphone
The boom cellphone handsfree consisted of an earphone and a mike at the end of the boom and has 4 connectors at the jack ( 2 for earphone and 2 others for mike). I tried to connect the earphone/external speaker socket of laptop to earphone connectors of the handsfree and I can hear the music from Media Player. But I could not hear my voice using sndrec32.exe when I spoke thru the mike that I connected to microphone socket of laptop.
Thanks GTAman.
You are right, the jack of cellphone is small (2.5mm) but I connected the jack to 2 larger jacks (3.5mm) for earphone and mike connectors.
Hope you can catch what I meant.
The mic is probably an electret type that needs power.
Maybe you had its two wires reversed so that it had the wrong polarity.
Maybe the laptop circuit is designed for a coil and magnet dynamic type of mic and therefore doesn't provide power for an electret type.
Maybe the mic is wired with 3 wires and one wire is shared with the earphone for power or for ground.
Agent 009, audioguru,zachtheterrible and GTAman,
Thanks for all of your information
May be at the end, I should get a separate headphones and a microphone :wink:
Just to satify my curiosity, how can I tell it's an electret or dynamic type of microphone ?
I know that mic's and speakers r "symmetric", u still can use one in place of the other, to some certain xtent (impedance, powerrating...). But I think for small headset like this one, the earphone could work very close to a microphone, and vice versa...
Which should be (from tip to ring) Ear,Mic, Ground ear, Ground mic.
As I have tried in the past, the microphone is an electric condenser mic, gardern variety minature. However, I think your notebook simply does not provide plug-in-power, as it is referred to.
Try plugging it into a PC and see how it goes.. Sound Blaster cards do provide plug-in power in the middle ring.
Thanks GTAman.
You are right, the jack of cellphone is small (2.5mm) but I connected the jack to 2 larger jacks (3.5mm) for earphone and mike connectors.
Hope you can catch what I meant.
indecided is right, it's a Nokia handsfree.
I have rewired the 2.5mm jack with 2 of 3.5mm jacks and also the order of the rings is like indecided wrote.
I will try to provide the power to the electret mike just like the link by indecided. Rig them on a breadboard and using a 9v battery.
Hi All, back with you again :?
I googled and came up with this link https://www.epanorama.net/circuits/micamp.html.
I did the breadboarding with a 9v battery as power source and tried to connect the circuit to my laptop. When I recorded my voice using sndrec32.exe, I could hear my voice but with background of high pitch noise due to interference.
How can I avoid or minimize the interference? Should I use a screened cable or put the whole circuit in a metal box ?
Your headset microphone probably has a screened cable to avoid interference. You added a resistor to power it. Didn't you use screened cable to feed it to your laptop? Unscreened cable makes a nice antenna for the very sensitive mic input on the laptop. :lol:
Thanks audioguru for your quick reply.
Right, the electret mike got power via a resistor, just like the article in the link I provided. I intended to put the circuit on a PCB, so the output of coupling cap soldered to 3.5mm jack that will be put into laptop mike input socket ( should be no extension wire actually )
The previous story I told you is what I experienced using a breadboard, so I had to use extension unscreened cable
Do you think I need an audio bandpass filter to get rid of interference. If you do, can you provide the link to the audio bandpass filter schematic or article ?
Thanks in advanced.