Animal
08-25-2006, 09:19 PM
So I got a little bored a few nights ago, started playin around with VoIP. As cool as it is, I kinda hate having to sit in front of teh computer with headphones on during the length of the conversation. So.... I started googling and playing around.
1761
Sweet. Separated audio in and out from the asynchronous telco signal. Circuit draws about 15mA @ 9VDC (Telcos use a current switch to turn the line on/off. I use this switching property further on, so keep it in mind.)
Headed on over to Radio Shark and picked up a protoboard and stuck parts to it for a permanent circuit.
1762
Used some old parts I had collected over the years (This is why I don't throw non-working electronics away. I pillage components off them for use in later projects). Total cost was about $8, but i'm sure you could get it for about $4 if you don't go to radio shark.
Add some zipties, a battery, and a phone cord....
1763
The circuit doesn't draw any current when the phone is on-hook (Handset on "Standby"). The phone goes into a high-impedance (About 600Ω) state and waits for either a call (approx. 49VAC from telco) or for the handset to pick up (Switches to low-impedance closed-circuit state). This allows me to keep the battery attached and not run it down when i'm not using it.
1764
Phone base. Old $20 cordless I bought when I was at UW. Since I don't need a landline anymore, this thing's been sittin in my closet for several years now. White cable to the right with the red velcro strap on it is 120VAC that powers my computer.
1765
And in use on my computer. Mic in, headphones out. And it works great. I'm told there's a little bit of echo on the line, but that's due to the telco using an asynchronous line. Volume and clarity on far-end is just as good as using my computer's mic, same with audio on near-end.
Don't even think about pluggin' this sucker into the wall jack though. It'll sit there idle till someone called you, and then it'd probably explode.
yea... it's cool :D
1761
Sweet. Separated audio in and out from the asynchronous telco signal. Circuit draws about 15mA @ 9VDC (Telcos use a current switch to turn the line on/off. I use this switching property further on, so keep it in mind.)
Headed on over to Radio Shark and picked up a protoboard and stuck parts to it for a permanent circuit.
1762
Used some old parts I had collected over the years (This is why I don't throw non-working electronics away. I pillage components off them for use in later projects). Total cost was about $8, but i'm sure you could get it for about $4 if you don't go to radio shark.
Add some zipties, a battery, and a phone cord....
1763
The circuit doesn't draw any current when the phone is on-hook (Handset on "Standby"). The phone goes into a high-impedance (About 600Ω) state and waits for either a call (approx. 49VAC from telco) or for the handset to pick up (Switches to low-impedance closed-circuit state). This allows me to keep the battery attached and not run it down when i'm not using it.
1764
Phone base. Old $20 cordless I bought when I was at UW. Since I don't need a landline anymore, this thing's been sittin in my closet for several years now. White cable to the right with the red velcro strap on it is 120VAC that powers my computer.
1765
And in use on my computer. Mic in, headphones out. And it works great. I'm told there's a little bit of echo on the line, but that's due to the telco using an asynchronous line. Volume and clarity on far-end is just as good as using my computer's mic, same with audio on near-end.
Don't even think about pluggin' this sucker into the wall jack though. It'll sit there idle till someone called you, and then it'd probably explode.
yea... it's cool :D