DC 1.5V-9V FM Wireless Microphone DIY Electronic Learning Kits 80MHz-108MHz

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Visit store<br>Items for sale<br>About us<br>Product Details<br>Enhanced wireless microphone, FM FM work, good sound quality, with ordinary radio to listen. Microphone to the sound signal into an electrical signal, the first level of audio voltage amplifier to send modulation level, so you can pick up farther and weaker sound. After the oscillation of the modulation of the high-frequency signal and then by a tuning power amplifier to send the antenna to launch, launch distance farther and reduce the impact of the antenna to the oscillation level, reduce harmonics. According to the circuit installed, the frequency of about 83MHz or so, just turn the coil L to a little bit, so that the oscillation frequency of work in the 88MHz-108MHz can be, with any FM radio to receive the high-frequency signal, And the sound signal is restored from the high frequency signal. Also equipped with an external audio socket and adjustable resistance to adjust the input audio signal attenuation.<br>the performance parameters:<br>Frequency range: 80MHz-103MHz (according to the circuit diagram parameters, only adjust the coil pitch)<br>Working voltage: 1.5V -9V<br>Radius: more than 100 meters 4.5V voltage, the general radio to receive, wireless microphone antenna for the 50cm long thin wire, in the high-rise residential area to do the experiment)<br>MIC will be the natural sound signal into audio signal, the C2 coupling to the base of Q to be modulated, when there is a sound signal, the transistor junction capacitance will change → oscillation frequency changes, complete the frequency modulation, that is, FM The And then by the C6 coupling to the high-frequency tuning amplifier circuit has been modulated high-frequency signal amplification, and then through the C12, L3 and antenna TX out of the frequency of the sound signal changes with the changes in high-frequency electromagnetic waves.<br>Where R1 is the microphone MIC bias resistance, generally selected in the 2K-5.6K. R4 is the collector resistance. R5 is the base resistor, providing a bias current to Q1. R7, R8, C5, L1, C8, C7 to form a high-frequency oscillation circuit, R7 to the Q2 base to provide bias, C5 and L1 oscillation circuit, Q3, R9, R10, L2, C10, C11 constitute a high-frequency power amplifier circuit. C8 is a feedback capacitor, R8 from the stability of Q2 DC operating point, C7 DC output AC capacitor; R9 to the power transistor Q3 to provide the base current, C10 and L2 amplification tuning circuit, and the oscillation circuit C5 and L1 tuning at the same frequency to get the maximum output power, the emission distance farthest.<br>We will launch the frequency of the FM radio band, so you can cooperate with any FM radio to receive the high-frequency signal, and from the high-frequency signal to restore the sound signal to complete a variety of purposes.<br>Package Include:<br>1 x  DC 1.5V-9V FM Wireless Microphone DIY Electronic Learning Kits 80MHz-108MHz<br>Payment Method<br>Shipping Policy<br>Returns & Refund Policy<br>Feedback<br>Payment Method<br>EBAY Managed Payment.<br>But we only<br>Accept<br>your<br>Ebay Address<br>, please Make sure it's 100% right.<br>Payment must be received in 5 business days of auction closing.<br>Please leave note for your special request (e.g. Colors or Size) in PayPal when you pay the order.<br>Any special request cannot be accepted after 24 hours of payment, because most of orders will be processed instantly and same day dispatched.<br>Shipping Policy<br>1. We only ship to the confirmed address provided by eBay. please make sure your ebay address is 100% matches the address you would like us to ship to. If not, please let us know before we sent you the package, or we will not be responsible for any loss. hope you could understand.<br>2. Orders will be processed instantly and dispatched within 1-3 business days except hoilday, so we do NOT accept any email/message note after you place orders.<br>3. All package need to wait 30 days,Please take care it.Less than 30 days,we can't take a refund.<br>Returns & Refund Policy<br>All package need to<br>wait 30 days<br>(US only n<br>eed 7-10 days)<br>,<br>Please take care it.Less than 30 days,we can't take a refund<br>.<br>If the item is defect when you receive it or you are not satisfied with it, please return it within 14 days for a replacement or money back. But the items must be back in factory