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Miscellaneous telephone circuit diagrams

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Telephone Ring Generator Using Switching Supply
Telephone Ring Generator Using Switching Supply
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]

Telephone Ring Generator Using Small Power Transformer
Telephone Ring Generator Using Small Power Transformer
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]

Tel Protection Filter
Tel Protection Filter
April 25, 2010

It is a simple circuit of protection of telephone line from hypertensions. Placed in line and before the telephone appliance. [more]

ADSL Filter for Tel Line
ADSL Filter for Tel Line
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]

ADSL Filter for Tel Line
ADSL Filter for Tel Line
April 14, 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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