Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Digital tachometer for my turntable
Digital tachometer for my turntable
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old Yesterday, 03:36 PM   #1
JosM is offline JosM  Netherlands
diyAudio Member
Join Date: Feb 2008
Location: The Hague
Default Digital tachometer for my turntable

Dear friends,

I would like to built a digital tachometer for my turntable. Not with a processor or stuff like that, but with "old fashioned IC's ( TTL or CMOS) and NIXIE tubes. Who Could Help me with a schema or article? Thank you.
  Reply With Quote
Old Yesterday, 04:53 PM   #2
Pyramid is offline Pyramid  United States
diyAudio Member
Pyramid's Avatar
Join Date: May 2006
Location: Behind the Cheddar Curtain
Difficult to do with any accuracy without using math (uP).

For high frequency signals, a counter is used with a defined gate period. The slower the input frequency, the longer the gate period becomes especially as the accuracy (to the right of the decimal point) increases. To measure a frequency of 60Hz using a 1 second gate to count pulses would produce a result 60, with 1 Hz resolution. To get 0.1Hz resolution would require a gate time of 10 Sec which produces a count of 600 and the decimal is put between the two zeros.

A turntable platter is slow moving; counting single pulses per revolution would have a gate time of 60 Sec for a resolution of 1RPM. If you use a rotary encoder to produce many pulses per rev, you will need one with thousands of pulses per rev, or do some math: An encoder with 6K PPR will give a count of 3333 with a 1 second gate with resolution of 0.01 RPM at 33 RPM and a count of 4500 with a 1 sec gate at 45 RPM:

Count=RPM*PPR*Gate/60 where gate is in seconds.

If you have an encoder with 2560 PPR, your gate time would be 2.34375 Sec for both 33 & 45 RPM and produce counts of 3333 and 4500.

To get resolution 3 places to the right of the decimal would require an encoder with 10's of thousands of PPR or a gate time of 10's of seconds.

You could also preload a counter with 78333 and count down at 25K pulses/sec using 1 revolution as a gate. This will give you accurate results for 45.000 and 33.333, but inaccurate results the farther away you get from either of those 2 numbers. The 74C192 counter IC is a BCD 10 up/down counter with preset inputs and could be used for this application. 7447 BCD to 7 Seg decoders could drive the digits.

Last edited by Pyramid; Yesterday at 05:05 PM.
  Reply With Quote


Digital tachometer for my turntableHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Digital Tachometer for record player (LCD display) JOHNNYCR100 Analogue Source 298 8th October 2018 09:47 PM
Turntable in digital system Gats80 Analogue Source 1 12th January 2018 07:54 AM
Digital Turntable Tachometer and DDS based PSU Pyramid Vendor's Bazaar 234 6th November 2017 01:57 AM
Have you discovered a digital source, that satisfies you, as much as your Turntable? Joel Wesseling The Lounge 1493 16th October 2015 03:23 AM
a digital turntable????!!!!! Daniel-A Analogue Source 2 15th May 2004 06:59 PM

New To Site? Need Help?

All times are GMT. The time now is 07:47 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio