7 / 15 watt FM Transmitter PLL stereo digital circuit

A very high quality stereo FM transmitter circuit , thoroughly time tested ,highly reliable, crystal controlled PLL based for zero  frequency drift is reviewed below. The main circuit uses a very popular IC -KT0803L ,to develop two channel stereo audio modulated FM signal from76 MHz to 108 MHz covering the FM band of  88 MHz to 107 MHz feeding  to 3 stage buffering before being fed to the final power amplifier using most commonly used 2SC1971 for 7 watt or MOSFET -RD15HVF1 for 15 watt. But unfortunately most commercially available 2SC1971 or  RD15HVF1 are duplicate. Thus if one ventures trying any circuit with this power Transistor/ MOFET usually are unsuccessful. So I strongly recommend to go for readymade units. Aux audio is directly fed at pin 6 & 7 while for mic input it is amplified by LM358 and then…

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W1209 Temperature Control Switch

Digital Temperature switch

DESCRIPTION The W1209 is a very low cost still highly practical a thermostat controller. With this module, one can control power to most types of electrical loads on the temperature sensor sensed by the supplied NTC temperature sensor. The best part is that for this no programming knowledge is required. 3 push button switches are used for configuring various parameters for on & off a relay triggered by changing temperatures. The relay switch contact handles a maximum of 240V AC at 5A or 14V DC at 10A. The current temperature is displayed in degrees Centigrade via its 3 digit seven segment display and the relay state by an onboard LED.  SPECIFICATION Temperature Control Range: -50 ~ 110 C Resolution at -9.9 to 99.9: 0.1 C Resolution at all other temperatures: 1 C Measurement Accuracy: 0.1 C Control Accuracy: 0.1 C…

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