Igor Burger has touted the simplicity and low cost of his timer, and rightly so. It is a marvel of compact, low-cost, lightweight design. However, he cannot cost-effectively provide it for U.S. flyers from the Slovak Republic where he lives—but he has made available, through the Internet, the binary code for his microcontroller and visual instructions for making the soldering connections to the 3-pin connector (four of the eight pins are clipped off, the remaining four pins are bent around and soldered to the 3-pin connector).
     The timer can be programmed by switching off the power lead after about one second. The next time the timer is turned on, the pulse width gradually increases from the “off” throttle setting; when the RPM or power reaches the desired level, the power must be switched off and this power level is stored in non-volatile memory. The next time the timer is switched on, it must be left on for as long as the desired flight time. From then on, until re-programmed, the timer will use these power and flight time parameters. Igor has also noted that one can use the Jeti Spin programming box.
     I have built a couple of these timers, and they perform as promised. For example, I programmed one for a pulse width of about 1.32 milliseconds and a flight time of five and a half minutes. Looking at the output on an oscilloscope, the pulse width varied between about 1.32 and 1.35 milliseconds at a frequency of 76 Hz (higher than the nominal value of 50 Hz) and then went to an off throttle setting of 0.90 milliseconds after the programmed flight time.
     The microcontroller and connector cost $2.31 plus postage/handling charges, in single quantities. I can provide a programmed microcontroller and the connector for $4, postpaid in the U.S.—if you want to solder it together, following Igor’s instructions. Alternately, I have a printed circuit board that allows me to make the connections in a more conventional manner. I am making this available to U.S. flyers for $10 postpaid. I’ll pre-program it for the power/RPM and the flight time, if you wish. (I still prefer my own timer for most applications, but this timer works as advertised and is certainly the low-cost champ. It also weighs less than 0.2 ounce!)
     The following picture shows a timer constructed using Igor’s method, the printed circuit board version, and (for size comparison) a dime.
             Will Hubin, 719 Cuyahoga St., Kent, OH 44240. whubin@kent.edu

Yes that timer needs 5V power supply on red line. But its consumption is very low and you can make very simple unit making 5V from one 7805 chip directly from power battery. Or even one resistor on 5V zener diode will work as well.

Igor has kindly provided updated software, with two important improvements: 1. There is now a 30 second delay after the button is pushed (to enable the flyer to get to the circle in a contest environment) and 2. the pulse width is now very stable during the flight time (within a few microseconds, anyway).