hi all
i make project that can detect DTMF/SCK by sm8223 IC,but i want when i recieve call make hook-off to send some command by AVR controller (mega16),
is there method that i can make hook-off ?
thanks alot
A 470 ohm resistor across a North American telephone line will dissipate about only 0.21W which is not a lot. Use a 0.5W resistor in opean air and it will be fairly warm, not hot.
A can of beer "opens", not a phone line.
A phone line goes "off hook".
If a can of beer goes off hook then you are plastered and should not drink any more beer.
But many weird things happen in Syria? Like hardly any alcohol in beer?
A can of beer "opens", not a phone line.
A phone line goes "off hook".
If a can of beer goes off hook then you are plastered and should not drink any more beer.
But many weird things happen in Syria? Like hardly any alcohol in beer?
A 470 ohm resistor across a North American telephone line will dissipate about only 0.21W which is not a lot. Use a 0.5W resistor in opean air and it will be fairly warm, not hot.
Your country is very strange:
No beer.
Extremely high telephone line current.
I won't talk about your religion (Muslim?).
250mA in 680 ohms produces 42.5W which will quickly smoke a 4W resistor. Maybe the current is only 25mA.
Current is measured in series with the load, not "across" the load.
Put your current meter in series with your normal telephone. Then lift the telephone handset and see what the current is. That will tell you the current you need to use to simulate "off hook".
Your country is very strange:
No beer.
Extremely high telephone line current.
I won't talk about your religion (Muslim?).
250mA in 680 ohms produces 42.5W which will quickly smoke a 4W resistor. Maybe the current is only 25mA.
Current is measured in series with the load, not "across" the load.