This is FM transmitter circuit without Coil,using inverter digital IC as main and controlled frequency is precise by crystal. Figure 1 the circuit diagram In Figure 1 is RF oscillator circuit which use a inverter IC1/2 and ceramic crystal filter 10.7 MHz to use drive IC1/4 – IC1/6 by through IC1/3. When inverter in parallel form this impedance output is low thus they can drive directly an antenna. When output of IC1/4 – IC1/6 are square wave which have much more internal harmonic. The harmonic number 9 of frequency 10.7 MHz (96.3 MHz) will take place at the center of …
This circuit is a 1.5V FM transistor circuit that use also two transistors like others circuit before. But this circuit is special that we use a varicap diode. Figure 1 is a schematic diagram – This circuit use the varicap diode number: SD111 or will use number 1S553, 1S85 instead. – The both transistors will be used the 2SC838 or this circuit use many number : 2SC458, 2SC460, 2SC461, 2SC784, 2SC785, FCS9016, FCS9018. -The coil-L is 7 turns of 22 swg wire wound with a inside diameter air core of about 5mm. Then stretch the coil to width of 12 …
Today lets to see the simple FM transmitters,90-100MHz that use two transistors, apply power supply with 1.5V battery The coil-L is 8.5 turns of 22 swg wire wound with a inside diameter air core of about 5mm. Then stretch the coil to width of 9 mm.  Figure 1 The schematic circuit diagram To tap out to the antenna at 3 turns (from input voltage) then adjust the all current of this circuit by Stretching or shrinking the coils and adjustable TC (trimmer) to have the current approximately 3mA the frequency in 90-100 MHz range. Figure 2 the components layout connection …