Looking for a frequency divider IC with multiple frequency outputs... - Page 1
Forum section: electronics / beginners

author: LinuxHata
author_rank: Frequent Contributor
timestamp: November 04, 2023, 06:38:00 pm
content: Hello.I'm looking for an IC like CD4521, but which will be able to output F/2, F/4, F/8, F/16 at different pins at same time. The operating frequency will be within 20kHz, so not looking something for RF.I know it can be done with CD4017s cascaded, but I'd like to have a single IC solution, if possible.Thanks!

author: kripton2035
author_rank: Super Contributor
timestamp: November 04, 2023, 07:32:35 pm
content: make it with a pic or an arduino, at this low frequency it should do it easy

author: oPossum
author_rank: Super Contributor
timestamp: November 04, 2023, 07:44:27 pm
content: CD4040, 74HC4040, 74HC161

author: CaptDon
author_rank: Super Contributor
timestamp: November 04, 2023, 08:11:39 pm
content: There must be at least 10 different CMOS and 10 different TTL BINARY COUNTERs available. Have you looked?? There are syncronis and ripple styles in both series and 4 stages are typical with more than 4 easily available in a single package. 7493 comes to mind although it is a ripple style.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: November 04, 2023, 08:23:43 pm
content: Thanks!I almost "forgot" that counters can be used as dividers, I was looking for a special, "divider" IC. I Think CD4040 is quite nice.I see it has many outputs in a single packaging, so maybe there's a dual or quad counter, with only 4 outputs, but still, in one physical enclosure?Because I'll need 12 of these, so saving space will be a good thing.

author: edavid
author_rank: Super Contributor
timestamp: November 04, 2023, 08:27:37 pm
content: CD4520 is a dual 4 bit counter in a 16 pin package, so that would save space.Is this for a musical instrument?

author: kripton2035
author_rank: Super Contributor
timestamp: November 04, 2023, 08:39:03 pm
content: you could pack all 12 dividers in ONE single pic, in a tssop package it could be very small...

author: edavid
author_rank: Super Contributor
timestamp: November 04, 2023, 08:50:28 pm
content: Quote from: kripton2035 on November 04, 2023, 08:39:03 pmWhat model of PIC can generate 48 divider outputs?OP hasn't told us how the dividers are clocked, so it might also need 12 inputs.

author: liaifat85
author_rank: Regular Contributor
timestamp: November 05, 2023, 07:36:52 am
content: You can try CD4046.https://www.ti.com/product/CD4046B

author: RJSV
author_rank: Super Contributor
timestamp: November 05, 2023, 08:32:47 am
content: Just be aware, CD4020 skips two of the outputs, of the 14 stages.So, while divide by 4 and by 8 are present, internally, those two are not brought outside the IC, to pins. On IC pins layout, they list Q1, (as first divide) but next is Q4 (through Q14).

author: RJSV
author_rank: Super Contributor
timestamp: November 05, 2023, 08:40:38 am
content: So the 4020 skips having output for input/4 and input/8, so better to use CD4040, if you can get that part.Radio Shack, in the day, seemed to only carry the CD4020 type.

author: kripton2035
author_rank: Super Contributor
timestamp: November 05, 2023, 08:50:21 am
content: Quoteyep that needs some more details from the OP

author: RoGeorge
author_rank: Super Contributor
timestamp: November 05, 2023, 09:08:29 am
content: From the TTL series,SN74x93asynchronous 4 bits counter,SN74x193synchronous up/down counter, where x can be: '', 'F', 'S', 'LS', 'HC', 'HCT', etc.- HC is pin compatible with TTL, but a CMOS, with max supply voltage 6V (typical TTL is 5V)- HCT, same as HC, but with inputs level as in TTL (HC has 0/1 separation at Vcc/2, not like TTLs)This Texas Instruments databook has the TTL family listed by a functional index, counters and/or flip-flops can make frequency dividers:https://archive.org/details/bitsavers_tidataBookVol1_11973959/page/n35/mode/2up

author: LinuxHata
author_rank: Frequent Contributor
timestamp: November 08, 2023, 04:42:32 am
content: PIC is already outputting 12 different frequencies at different pins. Yes this is the kinda of an electric organ.Technically, I can go with TSSOP-64 or even 80 pin case and generate all 48 signals altogether, but this is far beyond my coding abilities

author: RoGeorge
author_rank: Super Contributor
timestamp: November 08, 2023, 05:46:47 am
content: If the dividers are for a polyphonic musical instrument, mixing 2 or more notes might not sound as expected. In classic instruments, the notes are not synchronous, while in a chain of dividers all the notes will be in sync. This might make the mixed audio notes to sound bad.Once I've made a chain of counters (as a FPGA demo), then mixed the output bit of each note in various ways. They didn't sound very well. The following links show the sound of 4 different ways of mix synchronously generated notes:- Mixed with a logic OR gatehttps://youtu.be/lVeGMpV1Lcc- Mixed with a logic XOR gatehttps://youtu.be/hjtxLiOU1Kg- Mixed with a 4 bits adder followed by a Sigma-Delta DAChttps://youtu.be/q9rNk1ID0zU- Mixed with a 4 bits adder followed by a PWM DAChttps://youtu.be/bpaHlp6x54EYou may want to prepare some simulated WAV files at first, to decide in advance if the audio from two or more mixedsynchronouscounters is acceptable or not for the given application.

author: Terry Bites
author_rank: Super Contributor
timestamp: November 08, 2023, 01:30:24 pm
content: CD4017s are decade ripple counters. They are not binary counters and do not have f/2n outputs.Consider CD/HC 4024. If its for a polysynth then you really need separate VCO or code routines to add (pseudo)random phase dither.Electronic organs work ok with a top octave generator and a divider chain, but as noted, the sound tends to be dry.Also consider using your FPGA for an FM synthesis scheme-https://sonicstate.com/news/2020/02/24/build-your-own-fm-synth/