Difference between revisions of "Frequency Counter"

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** [https://owenduffy.net/blog/?p=11386 DL4YHF 50MHz counter on a Chinese TB-244746 PCB]
 
** [https://owenduffy.net/blog/?p=11386 DL4YHF 50MHz counter on a Chinese TB-244746 PCB]
 
* Frequency range: 1 Hz-50 MHz
 
* Frequency range: 1 Hz-50 MHz
−
* Crystal Test Range: 4 MHz-48 MHz - Replaced with pre-amp circuit
+
* Crystal Test Range: 4 MHz-48 MHz
 +
** Mods to replace crystal checker with sensitive pre-amp
 +
** [https://github.com/TheHWcave/PIC-freq.counter-modification/ PIC-freq.counter-modification]
 
* PCB size：8*5.3cm
 
* PCB size：8*5.3cm
 
** Fits in 100 x 60 x 25 mm enclosure
 
** Fits in 100 x 60 x 25 mm enclosure
 
* Source - [https://www.aliexpress.com/item/4001262793719.html?spm=a2g0o.productlist.0.0.a6a57b558PTLGq&algo_pvid=77bddd5c-6ae2-4082-8837-73945f792fae&algo_expid=77bddd5c-6ae2-4082-8837-73945f792fae-0&btsid=0bb0622f16000865130548256e846c&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_ AliExpress Frequency Counter] - Very inexpensive
 
* Source - [https://www.aliexpress.com/item/4001262793719.html?spm=a2g0o.productlist.0.0.a6a57b558PTLGq&algo_pvid=77bddd5c-6ae2-4082-8837-73945f792fae&algo_expid=77bddd5c-6ae2-4082-8837-73945f792fae-0&btsid=0bb0622f16000865130548256e846c&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_ AliExpress Frequency Counter] - Very inexpensive
−
* [https://github.com/TheHWcave/PIC-freq.counter-modification/ PIC-freq.counter-modification]
 
  
−
== Case ==
+
== Built into case ==
  
 
* P-Touch white on black labels
 
* P-Touch white on black labels
  
−
[[File:FreqCounterLabels.jpg]]
+
[[File:FreqCounter-P181-720px.jpg]]
  
−
* Inexpensive plastic case
+
* [https://www.ebay.com/itm/5pcs-100x60x25mm-Black-Plastic-Electronic-Project-Box-Enclosure-Instrument-Case/184015618380?hash=item2ad82f814c:g:iewAAOSwt6RduhdS 100x60x25mm Black Plastic Electronic Project Box Enclosure Instrument Case] - Inexpensive plastic case
 
** Plastic Waterproof Cover Electronic Project Instrument Enclosure DIY Box Case Junction Box Housing 100 x 60 x 25 mm Black
 
** Plastic Waterproof Cover Electronic Project Instrument Enclosure DIY Box Case Junction Box Housing 100 x 60 x 25 mm Black
 +
 +
[[File:Plastic_100x60x25mm-720px.jpg]]
 +
 +
* [https://www.ebay.com/itm/USA-12-PCS-5-5-MMX-2-1-MM-CHASSIS-PANEL-MOUNT-FEMALE-POWER-JACK-SOCKETS-NEW/264838025913?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 5.1mm Chassis mount power connector]
 +
 +
[[File:Power_5-1mm.PNG]]
 +
 +
* 7-9V in
 +
* Right angle header pins pointing to inside of card
 +
* 4-40 x 3/16” Machine Screws
 +
* 4-40 Standoffs
 +
 
* [https://www.aliexpress.com/item/32833340145.html?spm=a2g0o.productlist.0.0.68406390LYz5Rw&algo_pvid=0bbf736e-a88e-4ac7-9adc-03df1259669a&algo_expid=0bbf736e-a88e-4ac7-9adc-03df1259669a-0&btsid=0bb0622a16017274930362968ef528&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_ BNC connector - female chassis mount]
 
* [https://www.aliexpress.com/item/32833340145.html?spm=a2g0o.productlist.0.0.68406390LYz5Rw&algo_pvid=0bbf736e-a88e-4ac7-9adc-03df1259669a&algo_expid=0bbf736e-a88e-4ac7-9adc-03df1259669a-0&btsid=0bb0622a16017274930362968ef528&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_ BNC connector - female chassis mount]
−
* 5.1mm Chassis mount power connector
+
 
−
** 7-9V in
+
[[File:FreqCounter-Case-11-720px.jpg]]
  
 
== Rework - Add Pre-Amp ==
 
== Rework - Add Pre-Amp ==
  
 
* Re-uses extra HF transistor that would have been used by crystal tester oscillator
 
* Re-uses extra HF transistor that would have been used by crystal tester oscillator
 +
* AC coupled input
 
* Based on  
 
* Based on  
  
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=== Cuts/Jumpers ===
 
=== Cuts/Jumpers ===
  
−
* Front side cuts - blue
+
* Four cuts
 +
** Blue = 1 front side cut
 +
** Green =  3 back side cuts
 
* Jumpers Red
 
* Jumpers Red
  
 
[[File:FreqCounter_Rework_PCB_Front.PNG]]
 
[[File:FreqCounter_Rework_PCB_Front.PNG]]
  
−
* Back side cuts
+
* Green = Back side cuts
  
 
[[File:FreqCounter_Rework_PCB_Back.png]]
 
[[File:FreqCounter_Rework_PCB_Back.png]]
 +
 +
* Short etch on one cut
  
 
[[File:FreqCounter_Rework-Cuts-Back.PNG]]
 
[[File:FreqCounter_Rework-Cuts-Back.PNG]]
Line 58: Line 76:
 
* With parts
 
* With parts
  
−
[[File:FreqCounter_Rework-07.PNG]]
+
[[File:FreqCounter-P177-720px.jpg]]
 +
 
 +
* Wire on back
  
−
== Testing ==
+
[[File:FreqCounter_Rework_Wires_Back.PNG]]
 +
 
 +
== Initial Testing ==
  
 
[[File:FreqCounter_InCase.jpg]]
 
[[File:FreqCounter_InCase.jpg]]
  
−
* 4.9152 MHz crystal
+
* 4.9152 MHz crystal oscillator
−
* Scope frequency counter shows 4.19520 MHz
+
** Scope frequency counter shows 4.19520 MHz
−
* Freq Counter displays 4.9747 MHz
+
** Freq Counter displays 4.9747 MHz
−
* Difference = 500 Hz or 0.1% accuracy
+
** Difference = 500 Hz or 0.1% accuracy
 
* Can only adjust the variable capacitor in narrow range
 
* Can only adjust the variable capacitor in narrow range
 +
* Freq = 25,000 MHz - measured = 24.997 MHz
 +
** Error = 3 KHz / 25,000 KHz = 0.012%
 +
* Freq = 10.000 Hz - measured = 9.999 Hz = .01% error
 +
 +
=== Fixing the frequency error ===
 +
 +
* Calibrated using [[VFO-001#Calbration_Using_WWV|VFO-001]] calibrated to WWV
 +
* Replaced 22 pF cap with 2 series 33 pF caps
 +
** Far right near variable cap
 +
 +
[[File:FreqCounter-P177-720px.jpg]]
 +
 +
* Added 22 pF to back of board
 +
** Upper mid right
 +
 +
[[File:FreqCounter-P180-720px.jpg]]
 +
 +
* Why was this an error?
 +
** Perhaps the variable cap is too small for proper loading of the crystal
 +
** Could possible parallel a 10 pF cap with the variable cap?
 +
 +
== Firmware Mods ==
 +
 +
* [https://github.com/TheHWcave/PIC-freq.counter-modification/tree/master/HiRes_Freq_RPM1234_Event_counter HiRes_Freq_RPM1234_Event_counter]
 +
** [https://hackaday.com/2019/04/30/hacking-a-cheap-ebay-frequency-counter/ HACKING A CHEAP EBAY FREQUENCY COUNTER]
  
 
== Reviews / Builds ==
 
== Reviews / Builds ==

Latest revision as of 14:17, 1 November 2020

FreqXounter-Kit-Assembled-02.PNG

Features

Built into case

  • P-Touch white on black labels

FreqCounter-P181-720px.jpg

Plastic 100x60x25mm-720px.jpg

Power 5-1mm.PNG

  • 7-9V in
  • Right angle header pins pointing to inside of card
  • 4-40 x 3/16” Machine Screws
  • 4-40 Standoffs

FreqCounter-Case-11-720px.jpg

Rework - Add Pre-Amp

  • Re-uses extra HF transistor that would have been used by crystal tester oscillator
  • AC coupled input
  • Based on

Pre-Amp schematic

FreqCounter PreAmp Schematic.PNG

When building kit, do not install

FreqCounter DoNotInstallParts.PNG

Cuts/Jumpers

  • Four cuts
    • Blue = 1 front side cut
    • Green = 3 back side cuts
  • Jumpers Red

FreqCounter Rework PCB Front.PNG

  • Green = Back side cuts

FreqCounter Rework PCB Back.png

  • Short etch on one cut

FreqCounter Rework-Cuts-Back.PNG

  • Details of preamp input pin

FreqCounter Rework-06.PNG

  • With parts

FreqCounter-P177-720px.jpg

  • Wire on back

FreqCounter Rework Wires Back.PNG

Initial Testing

FreqCounter InCase.jpg

  • 4.9152 MHz crystal oscillator
    • Scope frequency counter shows 4.19520 MHz
    • Freq Counter displays 4.9747 MHz
    • Difference = 500 Hz or 0.1% accuracy
  • Can only adjust the variable capacitor in narrow range
  • Freq = 25,000 MHz - measured = 24.997 MHz
    • Error = 3 KHz / 25,000 KHz = 0.012%
  • Freq = 10.000 Hz - measured = 9.999 Hz = .01% error

Fixing the frequency error

  • Calibrated using VFO-001 calibrated to WWV
  • Replaced 22 pF cap with 2 series 33 pF caps
    • Far right near variable cap

FreqCounter-P177-720px.jpg

  • Added 22 pF to back of board
    • Upper mid right

FreqCounter-P180-720px.jpg

  • Why was this an error?
    • Perhaps the variable cap is too small for proper loading of the crystal
    • Could possible parallel a 10 pF cap with the variable cap?

Firmware Mods

Reviews / Builds

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