ARDF timer

ON7YD
ARDF

timer

Select :
Partlist	Scematics	Functional description
PCB	Download	DIP switch selections

Partlist
IC1 : PIC16C54XT ^*	IC2 : 78L05	Q1 : 3.2768MHz	T1/2 : BC547c
C1/2 : 22p	C3/4 : 100n	C5/6 : 100p	C7/8 : 100n
C9 : 10µF/10V	R1 : 470	R2/3 : 4k7	R4/5 : 3k3
R6/7 : 1k8	R8 : 8x47k	S1 : DIP switch (8)	D1/2 : LED 3mm

* : PIC16C54XT can be replaced by PIC16C84 or PIC16F84

DIP switch selections (S1)

Switch 1-3 : identification
Sw 1	Sw 2	Sw 3	Identification
off	off	off	MOE (1st min. of 5 min. cycle)
on	off	off	MOI (2nd min. of 5 min. cycle)
off	on	off	MOS (3rd min. of 5 min. cycle)
on	on	off	MOE (4rd min. of 5 min. cycle)
off	off	on	MOI (5th min. of 5 min. cycle)
on	off	on	MO (continue)
off	on	on	MOE (1st min. of 2 min. cycle)
on	on	on	MOI (2nd min. of 2 min. cycle)

Switch 4-8 : delay (value for each switch, add values)
Sw 4 : 30 min.	Sw 5 : 1 hour	Sw 6 : 2 hours	Sw 7 : 4 hours	Sw 8 : 8 hours

Functional description

This timer controls ARDF transmitters in accordance to the international ARDF rules. It can be used with 3.5MHz and 144MHz transmitters. Although it is small (PCB is 48x36mm), low cost and has a low power consumption (less than 5mA at 9 to 15V) it is a complete ARDF timer.

Identification (S1-1/3)
In addition to MOE- MO5 in a 5 minute cycle and MO (continious), a MOE and MOI in a 2 minute cycle are available (for training purposes).

Delay (S1-4/8)
A delay time up to 15.5 hours is programable. The delay starts after synchronisation and during this delay the timer will not drive the TX. This allows the organiser to hide the transmitters up to 15.5 hours prior to the first start, keeping the TX positions hidden for the competitors and saving the batteries.

RESET
After reset (pull RESET to ground) the timer will start with the active minute of the programmed TX, the delay-time is ignored. Switching the power on will have the same effect as reset. The processor reads the DIP-switches after reset (or power on), later changes of the switches will NOT AFFECT the programming !

SYNC
This input can de used to synchronise multiple timers. Pulling the SYNC input to ground for at least 1 second will 'alert' the synchronisation. The timers are synchronised when the ground connection is interrupted !
After synchronisation the SYNC input is disabled, so in order to permorm another synchronisation the timer has to be reset (or switched off).

TX
This output is pulled to ground when the TX should be active, otherwise it is 'open'. The voltages applied to the TX or KEY output should not exceed 30V, the current should not exceed 50mA.

KEY
This output is pulled to ground when the TX should be 'key-down' (3.5MHz) or modulated (144MHz), otherwise it is 'open'.

LED D1
Diode 1 has a double function. During synchronisation it will light as soon as SYNC is pulled low for at least 1 second (the timer is ready for synchronisation). During the 'delay time' D1 will light during the first second of the active minute, this allows a control of the synchonisation.

LED D2
When the TX is active D2 will light in the rythm of the modulation. If the voltage (from the TX) applied to KEY exceeds 15V a diode (eg.1N4148) in series with D2 is recommended.

+12V

The timer needs a supply voltage between 9 and 15V, the power consumption is less than 5mA (no LEDs lighting).

Scematic diagram

The scematic diagram is included in the download package.

Printed Circuit Board

The exact dimensions of the PCB are 1.9 x 1.4 inch (48.3 x 35.6 mm).
A high resolution TIFF file of the PCB is included in the download package.

Download

Click here to download a ZIP-file that contains :

high resolution Printed Circuit Board (TIFF file)
PCB component layout (GIF file)
complete functional description and manual, including scematic diagram (WORD document)
software for PIC16C54XT (HEX file)
software for PIC16C84 and PIC16F84 (HEX file)
terms of usage and disclaimer (ASCII file)

You are visitor number

since 21 feb. 2000