Frequency Counter Project (Updated April 2007)

The frequency counter design is by JG6DFK and uses a PIC microcontroller - http://www3.justnet.ne.jp/~32lab/products/measure/PIC-FC1/doc_e.htm

Page 1 (Implementation Details)

Page 2 (PCB Component Overlay)

Page 3 (Parts List)

Page 4 (Updated Schematic)

LCD Module Data Sheet - Farnell Order Code 142-608. N.B. VSS=GND, VDD=5VDC, VO=VEE.

N.B. The display will appear blank until VR2 is adjusted for the correct voltage at VO.

LCD Controller Data Sheet - Samsung KS0070B.

Issues with the frequency counter:

1. So far three people who have built the frequency counter have found the 10MHz oscillator to be high. M0BLP found that adjusting the trimmer capacitor would bring the frequency no closer than 10.0005MHz and this corresponded to maximum trimmer capacitance. Those people requiring most accurate results may want to use an external 10MHz oscillator module (with TTL or CMOS output, not sinusoidal) of high stability in which case you should remove C7,C8,TC1 & X1, feed the external oscillator's output into the PIC's OSC1 pin and leave the OSC2 pin unconnected.
2. If the prescaler IC is not fitted it is suggested that you fit a 1KOhm resistor between pins 2&5 of the prescaler socket so that the PIC can correctly sense the state of switch S1b via inverter U1e.

Addition April 2007 by David G6KWA

3. To solve the problem of the reference oscillator being a bit high change C8 to 82pf
4. Should you want to build the prescaler it has been found that a seperate sub-board is necessary at the input socket.

Sub board Prescaler   If you build this then spin it round 90 clockwise so that the input capacitor has shorter leads.

Display shot of my FT290 2M signal

An Up to date link for the project

Files related to the project :
None