This is a FM transmitter circuit using Maxim semiconductors IC MAX2606. In the circuit the nominal frequency is set to 100 Mhz by inductor L1, (390nH) . The left and right channel audio signals from your source are added by R3 and R4, and attenuated by the POT R2. R2 can be used as a volume control .POT R1 can be used to select a channel of transmission between 88Mhz and 108Mhz.Use 80 cm long wire as the antena.
* An FM antenna from a old radio is a better option than the wire antenna.
IC MAX2606 Description
The MAX2605-MAX2609 are compact, high-performance intermediate-frequency (IF) voltage-controlled oscillators (VCOs) designed specifically for demanding portable wireless communication systems. They combine monolithic construction with low-noise, low-power operation in a tiny 6-pin SOT23 package.
These low-noise VCOs feature an on-chip varactor and feedback capacitors that eliminate the need for external tuning elements, making the MAX2605-MAX2609 ideal for portable systems. Only an external inductor is required to set the oscillation frequency. In addition, an integrated differential output buffer is provided for driving a mixer or prescaler. The buffer output is capable of supplying up to -8dBm (differential) with a simple power match. It also provides isolation from load impedance variations.
The MAX2605-MAX2609 operate from a single +2.7V to +5.5V supply and offer low current consumption. These IF oscillators can cover the 45MHz to 650MHz frequency range.
IC MAX2606 Absolute Maximum Rating
- VCC to GND..............................................................-0.3V to +6V
- IND to GND ................................................-0.6V to (VCC + 0.3V)
- TUNE to GND .............................................-0.3V to (VCC + 0.3V)
- OUT+, OUT- to GND ..................................-0.3V to (VCC + 0.6V)
- Continuous Power Dissipation (TA = +85°C)
- 6-Pin SOT23 (derate 8.7mW/°C above +70°C)...........696mW
- Operating Temperature Range ...........................-40°C to +85°C
- Junction Temperature......................................................+150°C
- Storage Temperature Range .............................-65°C to +150°C
- Lead Temperature (soldering, 10s) .................................+300°C
