![]() The VCO covers only a few MHz without readjustment. It uses a PLL frequency synthesizer built with MC145151, which covers the FM band in 100kHz steps. The PLL transmitter exciter has the functions of providing a stable, low noise, frequency-selectable RF signal and amplify it to a controllable output power sufficient to drive the power amplifier. Published:0 2:00:00 Author:muriel | Keyword: PLL transmitter View full Circuit Diagram | Comments | Reading(1196) PLL transmitter circuit The total current consumption of the entire 1 watt transmitter will be around 500 mA. T4 will have a current consumption of around 150 mA at full power output adjustments. Use a 12Vdc power supply to power up this fm broadcast circuit. The oscillator and buffer stage must be enclosed in a 1 mm copper case, then do the same with the T3 and T4 stages. Then power it off, connect the antenna and make the final adjustments for maximum broadcasting coverage distance. You must adjust it to obtain the maximum multimeter indication. Then connect this rf probe to the output and adjust all the 3 trimmers starting from T3 to output. Initially use 2 x 100 Ω 0.5W resistors in parallel at the RF output. If you decide to use 2N2219 transistor for the final stage of the transmitter you must know that the output rf power will be 0.4W.Īdjust the last 2 trimmers for maximum output power in the antenna. The output power will be lower but you get the idea. If you can’t find any, use a BD139 transistor but only for frequencies lower than 90 MHz. The final stage of the 1W fm transmitter is built with 2N4427 (recommended) or the transistors from the list. You must adjust the trimmer for maximum power. This stage is very important for proper functionality of the entire 1 watt fm transmitter. Connect the power supply and if you adjust the trimmer (variable capacitor) from T3 collector you can see how the fm transmitter power can be varied. If you put a small piece of wire on the T2 emitter you can see that the cover range of the 2 stage transmitter is about 3 meter.Īfter you are sure that your oscillator+buffer stage are working properly, remove the power supply and continue building the T3 resonance stage. This will give you a very stable transmitter frequency.įirst build the oscillator stage and the buffer, power it up and trim the 10k linear potentiometer untill you can here a blank signal on your receiver. ![]() You must use a LM7805 stabilizer for the oscillator diodes and one LM7809 for powering up the T1 oscillator stage. Next is a resonance stage and the final stage built with a minimum 1W transistor which must have a heatsink. It has 4 transistors, one is a very stable oscillator, followed by a buffer stage to prevent frequency variation when you adjust the transmitter. It does not store any personal data.Published:1 2:20:00 Author:muriel | Keyword: 1W, fm transmitterĪ very good 1 watt fm transmitter circuit, very easy to build circuit. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. The cookie is used to store the user consent for the cookies in the category "Performance". ![]() This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other. The cookies is used to store the user consent for the cookies in the category "Necessary". The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". The cookie is used to store the user consent for the cookies in the category "Analytics". These cookies ensure basic functionalities and security features of the website, anonymously. Necessary cookies are absolutely essential for the website to function properly.
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