FM WIRELESS MICROPHONE CIRCUIT DIAGRAM
This FM Wireless Microphone has long been an extremely favorite undertaking with newcomers and experienced constructors alike. It has been utilised within guitars and as the foundation of the remote control process. I do even so, get numerous requests for a greater driven circuit and much better microphone sensitivity. This Substantial Electrical power FM Wireless Microphone incorporates a improved frequency balance, over one Km range and is also very good on microphone sensitivity. This continues to be reached by including an RF amplifier buffer (with 10dB achieve) and an AF preamplifier to boost the modulation slightly. Building is fairly basic. L1 is 3.25 turns in spiral kind and it is an integral part on the PCB foil pattern. The two BC547 transistors might be changed with (almost) any small-signal NPN transistor, for example the 2N2222. The last stage is really a BC557 PNP basic reason device. In case you use different units then you really should opt for the 1M0 resistor for 5-volts DC with the collector of the the initial transistor.
Pick the 47K resistor for three - four volts to the collector on the third transistor. Right here is definitely the V5 part overlay drawing. Be aware that there's a modification: The PCB is 50mm x 25mm, somewhat greater compared to very first version but you can find three phases as opposed to just the a single. The primary prototype is shown over, beside the battery powering it. The output strength is about +10dBm which happens to be about 10dB greater than the first FM Wireless Microphone. This would theoretically give it three.12 instances the assortment (1.6Km) but I have only examined it employing a handheld receiver with the TX laying for the bench indoors. But I obtained a at ease 700 meters (in addition to a number of humorous seems to be from our neighbours). Above it is possible to see the addition of the "gimmick" capacitor added across the 12p tuning capacitor to reduce the frequency of the transmitter. Make the capacitor by twisting two lengths of single core insulated hook-up wire, about 2cm extensive. This tends to reduce the frequency to your bottom conclude of your band. Reduce brief the capacitor to increase the frequency to the desired ultimate frequency. In the event you reduce it a number of KHz too substantial then just twist the gimmick somewhat tighter. The PCB foil pattern and layout are going to be put inside download part of my homepages. Have fun and please bear in mind that the bigger energy of this undertaking may render it ILLEGAL as part of your very own nation. I can take no duty and it is actually as much as you to verify that you simply may legally use it. I'll take NO grievances from any country/state correctional facility.
