The 556 dual-timer circuit is a high-stability controller that produces accurate time delays or oscillations. The 556 contains two LM555s. The timing function uses an external resistor and capacitor. The two timers share a power supply and ground and operate independently of each other. This circuit can trigger and reset on falling waveforms. The output can sink or supply 200mA. Direct replacement for SE556/NE555; from microsecond to hourly timing; can work in monostable or multi-resonant mode; replace two 555 timers; adjustable duty cycle; output can supply or sink 200mA current; output and power supply Compatible with TTL; temperature stability better than 0.005%/C; normally open and normally off output. The KSPOWER brand 76W~100W DC adapters is one black or white color constant voltage mode, accepts universal input 100-240V AC voltage and provides the complete power transformers solutions covering the single output voltage ranging from 5Volt to 36Volt and the output current ranging from 100ma to 8000ma. The ac dc power adaptor follows high quality level VI energy efficiency and meet IEC/EN/UL 62368-1 safety standard, with UL/cUL CE FCC KC KCC TUV GS RCM CCC SAA C-Tick UKCA RoHS CB PSE PSB safety certificates export for global countries. The limited power source is Class I and Class II power designed with the standard AC outlet of IEC320-C14, IEC320-C6, IEC320-C8 and offers 3 years after-sale customer service. The external ac power adapter accepts various dc connector size for various audio/video and I.T.E applications and protections for short circuit, over load, over voltage and over temperature with green indication light for power on. power adaptor, dc power adapter, dvr adapter, limited power source, power transformers Shenzhenshi Zhenhuan Electronic Co., Ltd , https://www.szzhpower.com
This circuit provides a single tone rate that requires accuracy for the repeater. Half of the 556 dual timers are used as a one-shot MVBR with an ON (work forecast) time of approximately 400ms. The other half is a free oscillator, which does not work when monostable is low. When the talk switch is closed, the transistor begins to send a single tone group. In order to stabilize the frequency, the asterisk resistor must be cermet or wound. R1 is a 15 or 20-turn trimmer potentiometer with a low temperature coefficient and 30 Hz per revolution. 
September 22, 2022