Blinking Lights TDOA RDF Antenna Project

This article is a detailed description of how to source and assemble a wonderful little project originally published by Dave NZ1J. It takes a TDOA project documented on this site elsewhere to a new level. The original TDOA, built with a 555 timer, is extremely easy to build, but only gives an audio indication of the direction of the fox.

This project uses a PIC mcu and LED's to indicate the direction to the fox. It requires a bit more hardware to construct, but with a group buy, we were able to source the PCB and parts for around $26 ea.

See this video by Dave NZ1J of a demo ==> https://www.youtube.com/watch?v=mNqUKYkifOo

Below is the schematic and some photos to help with your build.
Note: that the electrolytic Capacitor C2 goes with the ground at the bottom, not according to the symbol, but rather the + sign on the top.

The BOM (Bill of Materials) is the following:

Item	QTY	Part	Digi-key Part Number	References
1	1	PIC Pocessor	PIC16F18324-I/P-ND	U1
2	1	14 Pin Socket	ED3114-ND	U1
3	1	78L05	497-7268-ND	U2
4	2	2N3904	2156-2N3904-FS-ND	Q1, Q2
5	2	PIN Diode	568-1922-1-ND	D1, D4
6	4	Green LED	C503B-GCN-CY0C0792CT-ND	D5, D6, D8, D9
7	1	Red LED	C503B-RCN-CW0Z0AA1-ND	D7
8	4	1k Resistor	1.0KQBK-ND	R3, R6, R13, R17
9	8	4.7k Resistor	4.7KQBK-ND	R2, R5, R10, R11, R12, R14, R15, R16
10	2	470k Resistor	470KQBK-ND	R1, R4
11	1	220pF Cap	399-14053-1-ND	C6
12	1	0.01uF Cap	399-9772-ND	C5
13	3	0.1uF Cap	399-4264-ND	C1, C3, C4
14	1	10uF Cap	493-17435-1-ND	C2 (Note: align according to the + symbol up)
15	1	1uH Inductor	78F 1R0K-TR-RCCT-ND	L1
16	1	Slide Switch	450301014042-ND	SW1
17	1	9V Battery Clip	36-232-ND	TP+

The files that were provided by Dave NZ1J to me so that we could get our own PCB's made and PIC chip programmed are available to our club members by contacting me by email at ve6pds @ this domain (caraham.org)

Also, Here is a blog posting: https://aerobatgeek2.blogspot.com/2022/03/blinky-tdoa-rdf-detector.html