Transmit Time Limiter


Posted on Feb 3, 2013

This circuit prevents making transmissions that are too long, which `time out` repeaters and/or tie up a communicatio


Transmit Time Limiter
Click here to download the full size of the above Circuit.

ns channel too long. On transmit, the PTT (push to talk line) from the microphone is at ground. This causes one input of the AND gate (4081) to go high. The 555 is held in the reset mode. An MC1453B monostable multivibrator generates a pulse to the 555 and causes it to produce a gate of length approximately l.liC, where R is selected for desired time delay and C is 100 ¥. The output of pin 3 of the 555 causes the 4081 gate to go high, turns on Ql, and keys the transmitter. At the end of the cycle (1.1/C), the AND gate will lose one input, which turns off Ql and unkeys the transmitter.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

TDA1554 / 22W Stereo Amplifier
Solid state stepping switch
Linear temperature-to-frequency
Lamp flasher circuit
Headlamp dimmer controlled foglamps FORD RAPTOR
Coin Toss Circuit
No headlights new switchswapped relays under hood fuses under
Capacitor charging and discharging
PCB exposure box Based on ATmega8 AVR microcontroller
12kW PFC Boost Converter
Integrated OCL power amplifier circuit composed by the TDA2040
IC OCL power amplifier circuit



Top