Impressive no?...
I actually wonder how accurate it is - whether it would even be legal to use (even if you kept it at the proper small power/distance limits) - or if it squirts noise all over the sidebands and such...
I must correct my post, it's not a Transmitter, it's just the FM modulation circuit for a Transmitter.
NE555 stops working at 200 kHz or so.
An FM transmitter for the Audio brodcast 88-108 MHz is not possible.
Perhaps use it for an transmission line for analog signals in an noisy enviroment.
Pelle
That is a highly imperfect FM modulator, as it only alters the ON time. OFF time remains the same. However, you can get rid of that problem by running it at 2x the desired center frequency and running it through a /2 flip flop.
In fact, I've used this very scheme (a current mirror for the charge current) in 555 timer circuits with it wired as a monostable, driven by a separate clock in order to get PWM control. I've used it for AM modulation at low frequencies (CMOS 555 timers can work to 2MHz) and low power, for class D audio amplifiers, PWM to a superbright LED and an infrared LED to send audio over a light beam, SMPS regulators, etc.
Hi , polymorph, yes another member of the LM555 appreciation society.
I have used a 555 as a simple temperature controller, with a thermistor and output relay, using the 1/3, 2/3 vrefs and the flip flop logic.
The LM555 is 43years old and still going well.
Tom...
I've used one when I only need one schmidt (sp?) trigger, for capacitance sensing/measurement, as wired and wireless tachometers, to generate a ramp (using a current mirror), to charge a capacitor for a Xenon flash, in a 16 channel light dimmer/controller, etc. I don't think I can remember all the ways I've used them, in bipolar and MOSFET versions.