Table 1
Part |
Description |
Radio Shack |
Digi Key |
Notes |
IC1 |
LM555 timer/oscillator |
276-1723 |
|
NE555, etc. |
Q1 |
2N3904 transistor |
|
|
NPN-50V-150mA |
R1* |
3M3 resistor |
|
3M3QBK-ND |
orange orange green gold |
R2 |
1K resistor |
|
1KQBK-ND |
brown black red gold |
C1* |
220µF, 16V capacitor |
|
|
electrolytic (see text) |
C2 |
220µF, 16V capacitor |
|
|
electrolytic |
A Couple of Final Notes:
o All partnumbers are Radio Shack/Tandy or DigiKey unless otherwise indicated.
o All resistors are minimum 5%, 1/4 watt, carbon, unless otherwise indicated. It's okay to use metal film or other
precision types. 3M3(R1) is the same as 3.3M
o With this circuit you can find your aircraft easily in high grass, corn fields, soybeans or whatever. As soon as
you power on your receiver the timer will start to count down.
o If you power the unit via the receiver battery, make sure to purchase a 3 - 6 volt buzzer! Remember that in
the case of a crash (heaven forbid!) the receiver may loose its power from the battery pack because of the
force of impact. It would be safer to provide the ADL with a 9-volt Alkaline battery + on/off switch and wrap
the whole thing in 1/4" SIG latex rubber.
o The timer, with the components shown above, goes off in about 18 minutes at 9-volt. To increase the delay, increase
the value of R1. Also, R1 could be made adjustable with a 5-Mega-ohm trimpot
of the proper wattage.
o A CMOS version of the 555 timer is available (MC1455P1), and
preferred, which will cut the powerdrain on battery powered circuits. The MC1455P1 is pin-compatible with the
NE555, and most other 555 chips. C1 and C2 are electrolytic capacitors (or tantalum) so watch the '+' and '-' orientation.
Q1 (2N3904) can be most any substitute so it's not critical; just watch the position of the emitter/collector as
some european type have them reversed (like the BC types).
o The ADL can be used for all forms of R/C equipment, the only thing needed may be to adjust the delay to tailor
your needs.
o This device is tested for interference with JR, Futaba, HiTec, Airtronics, Hobbico, and ACE radio equipment. None
were found and none are expected when used with other brands of Radio equipment.
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Copyright © 1996, Tony van Roon