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Telephone related circuit diagrams
June 22, 2010
This project is aimed to make the low cost intercom system by which eight telephone lines can be interfaced with this hardware. [more]
April 28, 2010
Audio from a telephone line can be obtained using a transformer and capacitor to isolate the line from external equipment. A non-polarized capacitor is placed in series with the transformer line connection to prevent DC... [more]
April 28, 2010
The telephone ring generator shown below generates the needed high voltage from a simple switching mode power supply (SMPS) which employs a CMOS Schmitt Trigger square wave oscillator, 10 mH inductor, high voltage switching transistor... [more]
April 28, 2010
This ring generator will ring a telephone once every 10 seconds. The interval between rings can be lengthened or shortened by varying the value of the 1 Meg resistor. The 70 volt/ 30 Hz ring... [more]
April 25, 2010
It's a very simple circuit, for the follow-up of baby. It can however be also used for other use, as intercom etc. In the place of M1 we can we use a simple electret mic... [more]
April 25, 2010
It is a simple circuit of protection of telephone line from hypertensions. Placed in line and before the telephone appliance. [more]
April 25, 2010
It ιs a simple circuit for the noise reject that exists in the telephone line in ADSL connections. It works in PSTN and ISDN lines, and is placed in line and before the telephone appliance. [more]
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