Here I place schematics of our devices for frequency, inductance and capacitance measure.

Frequency meter v3.1 (1Hz-1000MHz) (2003-2007)
Frequency function meter v2.4 F1-(1Hz-1000MHz), F2 (1Hz-50MHz) and F3(1Hz-50MHz) (2004-2005)
Frequency (1Hz-60MHz) and LC meter v1.2 (0.01pF - 150nF)(150nF - 1uF)(0.001uHy-100mHy)(2005-2008)

If you have interest in some of the meters we can build it for your own use.
For prices and time of building the device please contact us: LZ2GL

Brief history of first frequency meter. We start to make device with PIC16F84A by schematics from internet, ASM program I wrote too by materials from Microchip and other source code, which I found in WWW. Working on device started in the beginning of 2003 and in the end of March same year we finish ed the first variant. It measured quite well, in spite of small errors in my ASM code.

Next year 2004 we decided to improve frequency meter in fact to make other device which we called frequency function meter. Idea behind it was to measure sequential three different frequencies and to make a little calculation between them. One important calculation is F1 - (F2 + F3), where F1 - is frequency of VFO, F2 is BFO/VCO frequency and F3 is IF frequency. With this device we can measure RF for favorite factory transceivers.

During year 2005 after short research and with existing experience while making our new transceiver and its program, I made improvements in software of our two types of frequency meters. I improved code for reading keyboard, fix small error in main cycle for measure time. This error make following anomaly in precisions of 10 Hz -> 10.000.01 Hz last digit flowing between 0 and 1, which was normal but by going to less precisions like 10 kHz -> 10.02kHz here the last digit flowing between 1 and 2 instead of 0 and 1. The program mistake was that I was not count one ASM instruction of PIC16 which was combination between half instruction to open and half to close Freq Gate. The main cycle for time is developed by me with 4 nested levels. With this cycle I can make a lot of various combination of times which helps to use dividers of frequency on 64 or 256 in front of our device, which allows to measure frequency up to 1000~1500Mhz. 

After this we decide to make LC meter, after research we found that we need microcontroller to measure frequency and LC generator and the rest are only calculations. Formulas and schematics for LC generator have in many places on internet. One good place is http://my.integritynet.com.au/purdic/lc-meter-project.htm.
ASM code was developed by me, I use my program for frequency meter for my four nested cycle for time. I needed to use calculations for floating point from Microchip AN575 and the ASM code exceed 1Kb code page for PIC16F84 so I decide to use PIC16F88(PIC16F628/648).

After the device construction it was calibrated with standard capacitors and inductors from nation laboratory for calibration in Veliko Tyrnovo. After this error of device reach 1% in 1pF-100nF and 1% for 1uHy-1mHy, and for other diapasons 1-2% error.

During 2007 we upgrade frequency meter to v3.1. We remove 74HC164 to save power consumption and make 4 bit interface to LCD. Also we change our prescaler and start using PMB2313T for our UHF input. This prescaler is in SMD format and is with very good parameter in range 50MHz - 1.1GHz. We redesign PCB to fit in small box and we star using most of components in SMD format.

During 2008 we upgrade LC meter to v1.2. We redesign PCB to fit in small box and we star using most of components in SMD format. As optional we test with 74AC132 and reach a very good maximum frequence, up to 60MHz without high frequency prescaler.

Here are the schematics:

Frequency meter v3.1 ( as PDF)
(1Hz-50MHz) and (10MHz-1100MHz)

Frequency function meter v2.4 ( as PDF)
F1 (1Hz-1000MHz), F2 (1Hz-50MHz) and F3(1Hz-50MHz)

Frequency (1Hz-50MHz) and LC meter v1.2 ( as PDF)
(1Hz-60MHz), (0.01pF - 150nF), (150nF - 1uF) and (0.001uHy-100mHy)