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Miscellaneous telephone circuit diagrams
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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 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]
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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