Serial DRAM non voltizer


Posted on Feb 6, 2014

This device contains a ringing generator and a tone oscillator. The tone oscillator is set to either 350 or 440 Hz. The ringing generator is a potted module delivering 86 Vac at 20 Hz. It is available from a source listed in the reference. (View) At the instant that power is applied to the 555 astable, timing capacitor C1 is initially discharged,


Serial DRAM non voltizer
Click here to download the full size of the above Circuit.

causing the output of the chip output at pin 3 to be high. Once C1 has charged to about 2/3 of the supply voltage, its output goes low, and the discharge transistor turns on, draining the charge on C1. (View) The telephone audio interface-essentially, a simple isolation/couple circuit-isolates the phone line from any connected audio circuit without presenting any danger to the phone line, the equip-rnent, or the user. (View) Positive feedback is provided by resistor R4, which causes the latching. A positive pulse at the set input causes the output to go high and a reset positive pulse will return the output to es-sentially 0 Vdc. (View) The AD537 is well-suited for frequency-shift modulator and demodulator applications. Requir-ing little power, it is especially appropriate for using phone-line power. The Bell-System 202 data en-coder shown here delivers the mark frequency of 1. 2 kHz with the data input low. When the input goes high, the timing current increases to 165 A and generates the space frequency of 2. 2 kHz. The trim shown provides a ±10% range of frequency adjustment. The output goes to the required band-pass filter before transmission over a public telephone line. A complementary demodulator is easy to implement. (View) This circuit is designed to restrict phone calls with the area codes: 900, 976, and 540. This device uses a microcontroller to compare the DTMF decoded tones with telephone numbers stored in...




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Servo tester with PIC12F675
    Arduino Audio DAC Options
    The CUSB-36R Christmas Light Circuit
    programming pen usb interface
    Three-State Continuity Tester
    Police siren using NE555
    FM transmitter circuit diagram
    Dynamic Mic Preamplifier Circuit
    Solid State Tesla Coil/High Voltage Generator
    FM Wireless Microphone
    Practical sound level monitor circuit diagram
    With self-locking function of the forward start circuit
    Direct Box (instant music recording instrument for Musicians)



    Top