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Electronics => Projects, Designs, and Technical Stuff => Topic started by: Liv on March 05, 2015, 01:27:03 pm

Title: DIY interpolating reciprocal frequency counter FC-510
Post by: Liv on March 05, 2015, 01:27:03 pm

Interpolating reciprocal frequency counter FC-510

Features:

•   reciprocal counting + interpolation (3-rd generation by Pendulum classification)
•   main input frequency range: 0.1 Hz…100 MHz
•   period range    : 10 ns…10 s
•   measured single pulse duration: 100 ns…10 s
•   measured duty cycle   : 0.0000001…0.9999999
•   measured RPM: 6…999999 rpm.
•   measuring interval: 1 ms…10 s
•   analog interpolator resolution: 1 ns
•   average count: 1…100
•   IF range: ±99.9999 MHz
•   math: Fmin, Fmax, dF
•   hold: yes
•   programmed prescaler ratio: 1…1000
•   prescaler frequency range: up to 2 GHz
•   input impedance: 1 MOhm || 30 pF
•   input coupling: DC+AC, AC
•   input attenuator: 1:1, 1:10
•   sensitivity: 100 mV (up to 50 MHz)
•   max input voltage: ±50 V
•   comparator threshold: –0.5…+0.5 V; –5…+5 V
•   optional LPF: 100 kHz
•   reference: TCXO, ±2.5 ppm (-20…+70°C)

Title: Re: DIY interpolating frequency counter FC-510
Post by: Liv on March 05, 2015, 01:29:18 pm

Some photos:

Title: Re: DIY interpolating frequency counter FC-510
Post by: DmitryL on March 05, 2015, 01:45:12 pm

+1. I made this frequency meter about a year ago. Works like a charm.
For clocking I used a standard 10Mhz VTCXO with a trimmer resistor for fine freq. adjustment. Calibrated all thing by 1PPS from a GPS receiver.

Title: Re: DIY interpolating frequency counter FC-510
Post by: Liv on March 05, 2015, 04:03:39 pm

Firmware version 2.x supports 9-digit frequency display (for 1601 and 1602 LCDs) and level meter in second line (for 1602).

Resolution demonstration (sorry for unintelligible language, I will try to fix):

video (https://www.youtube.com/watch?v=VNKCnef-ynU)

Title: Re: DIY interpolating frequency counter FC-510
Post by: DmitryL on March 05, 2015, 04:42:13 pm

BTW, you forgot to mention that it is a _reciprocal_ counter, not a direct count one.
It makes a huge difference from specs perspective. 

Title: Re: DIY interpolating frequency counter FC-510
Post by: Liv on March 05, 2015, 05:02:36 pm

Thank you, I made correction of features list.

Title: Re: DIY interpolating frequency counter FC-510
Post by: DmitryL on March 05, 2015, 05:06:16 pm

Don't forget the topic name, it must be eye-catching! :)

Title: Re: DIY interpolating reciprocal frequency counter FC-510
Post by: Liv on March 05, 2015, 05:13:42 pm

OK, fixed.