Transistor Ringing Generator

The transistor ringing current generator converts the DC voltage of 24V into an AC ringing current voltage of 60~90V, which is used to supply the ringing of communication equipment, such as carrier machines, high-frequency terminals, wired telephones, etc.

1. Technical performance

(1) Input power: DC 24V ± 10%;

(2) Rated output: 60~90V AC;

(3) Frequency: 20 Hz ± 5 Hz;

(4) Working conditions: The device can be used continuously for 24 hours in an environment with a temperature of 5℃ to 40℃ and a relative humidity of ≤80%.

2. Component selection

Capacitors Cl and C2 are 1000μ/50V, C3 is 200μ/50V, and C4 is 10μ/150V. Resistor Rl is 200Ω, 1/2W, R2 is 1kΩ, 1W, R3 is 3.6kΩ, 2W, R4 is 5.1kΩ, 1W, and R5 is 20kΩ, 1W. All of the above are metal film resistors. Potentiometer RP is 33Ω, 1W. Zener diode VDl is 2CW75, and VD2 is 2CW73. Diodes VD3 and VD4 are 2CPl3. Transistor VTl is 3AD638, and VT2 and VT3 are 3AD30C. Signal lamp HL uses XDX-24V, 0.5A, and neon lamp uses NH0-4C (60V, 1mA). Power switch SA is KN3-3 (double-pole double-throw switch). The fuse FU is a BGXP-1 type 2A fuse. Transformer T is made of silicon steel sheet material, and the core cross-sectional area is 38×45mm2. N1 and N4 are wound with Φ0.25mm high-strength enameled wire for 39 turns, and N2 and N3 are wound with Φ0.49mm high-strength enameled wire for 189 turns, all of which are wound in parallel. N5 is wound with Φ0.35mm high-strength enameled wire for 840 turns.