Searching for the chip that produces this tone - Page 1
Forum section: electronics / general

author: nocamig429
author_rank: Newbie
timestamp: March 12, 2024, 01:43:02 pm
content: Hi!I've been intrigued recently on what chip originally produces this sound:https://youtu.be/iNpXCzaWW1sUnhappily all the physical devices I tracked down are using epoxi blobs :/Do anyone have any idea?

author: andy3055
author_rank: Super Contributor
timestamp: March 12, 2024, 02:25:02 pm
content: I have a bedside alarm clock that has the same chime. It is about 30 years old. Made in Japan .. HOSEKI. See photos.

author: nocamig429
author_rank: Newbie
timestamp: March 12, 2024, 04:06:14 pm
content: Thank you so much!I'm researching it now, it seems that this DIP-8 STP2740C is still sold, but most datasheets websites have no idea what it is and redirect to similar identifications that are mosfetsNot even STM (supposedly) seems to remember manufacturing these

author: wraper
author_rank: Unknown
timestamp: March 12, 2024, 04:15:54 pm
content: It's just a generic sound produced by huge number of different clocks and watches. There is no one specific chip that does it, there are hundreds if not thousands of them.

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 12, 2024, 04:31:32 pm
content: Quote from: andy3055 on March 12, 2024, 02:25:02 pmYou meant to say "I had a bedside alarm clock"Quote from: wraper on March 12, 2024, 04:15:54 pmMost will be simple non volatile memory based playback devices. Simple way to mimic it is to record the sound and reduce the amount of data to low sample rate 8 bits per sample and use a small microcontroller with PWM output to play it back.

author: wraper
author_rank: Unknown
timestamp: March 12, 2024, 04:58:28 pm
content: Quote from: pcprogrammer on March 12, 2024, 04:31:32 pmYou don't need PWM or ADC for this. There is no amplitude component in it, it's just a square signal switched on/off. To generate it, you just need to know its frequency and get right time intervals. Both are very easy to figure out.

author: Uunoctium
author_rank: Frequent Contributor
timestamp: March 12, 2024, 05:07:51 pm
content: totally OThttps://youtu.be/DLCkAwVkDlk?t=53

author: andy3055
author_rank: Super Contributor
timestamp: March 12, 2024, 06:34:25 pm
content: "You meant to say "I had a bedside alarm clock"" No, I really meant to say "I have" because it still works! I just dismantled it to get the pictures for the OP. Hope he can find it. It has some sentimental value in that, three of my workmates gave it to me when I left the company and the country as well, with a card that said, "... so that you will remember us for a long time..." The thing is still reminding me of them (all girls) every morning!

author: andy3055
author_rank: Super Contributor
timestamp: March 12, 2024, 06:41:36 pm
content: Found this:

author: soldar
author_rank: Super Contributor
timestamp: March 12, 2024, 08:38:22 pm
content: I analyzed the audio and it is extremely simple.Beeps are 2048 Hz. I suppose anything close will work. Sine or square should work.Beeps are 65 ms in duration followed (or preceded) by 60 ms silence.Four beeps with their silence = 500 ms. Followed by 500 ms silence. Entire long cycle is 1000 ms.This should be extremely simple to generate with software or with hardware.You can probably make both beep and silence equal length, 62.5 ms.It can be done with just a few HW components.You can generate beeps followed by silence continuously and then silence four out of every eight beeps.That youtube audio has way too much noise. It was just recorded with a microphone.I am attaching my own generation.The second file has beeps and silences of 62.5 ms, making the four beeps 500 ms then 500 ms silence.Analyzing the math it turns out 62.5 ms x 2048 hz is 128 cycles (2^11) and the entire sequence is composed of multiples of that so a 2048 Hz oscillator and a few gates will produce that.If I have not made mistakes along the way the diagram design should do it.555 can be used as oscillator although it can be generated many other ways.CD4020 (14 stage counter) or CD4040 (12 stage counter) should work as dividers.CD4073 is three 3-input AND gates. This can also be done easily by combining other gates or with discrete components.

author: nocamig429
author_rank: Newbie
timestamp: March 13, 2024, 06:50:47 pm
content: Amazing o-OThinking about it, it might have something to do with the quartz oscilator on the clock, since you probably can get 2048hz from 32768hz easily. Now I can surely generate it by hand, thank you so much!I'm still researching on the topic, since this became a really weird rabbit hole, I sent some e-mails to Hoseki, since they seem to have a lot of patents related to clocks and circuits, but I can't understand most of them cause they are in Japanese. I'm now wondering on who did this first, I doubt I'll easily find it, but its fun kinda.

author: soldar
author_rank: Super Contributor
timestamp: March 13, 2024, 08:12:57 pm
content: Exactly. 32768 is 2^15 so you just use a chain of 15 counter/dividers to get 1 Hz which is what moves the clockwork. From the same chain of counters you can extract the beeps as shown above.To the AND gate you can add another input to enable/disable the alarm sound.Interestingly I do not see a 15 stage binary counter chip, only the 74HC4020 which is 14 stage and would produce a 2 Hz output with a 32768 Hz input.

author: themadhippy
author_rank: Super Contributor
timestamp: March 13, 2024, 08:33:10 pm
content: hows about a 4060 divider chain and oscillator all in one

author: soldar
author_rank: Super Contributor
timestamp: March 13, 2024, 09:20:51 pm
content: 4060 includes the oscillator but is still only 14 stage counter which would output 2 Hz with a 32768 Hz oscillator.

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 14, 2024, 07:33:20 am
content: Or an ATtiny that can easily do it without any other components apart from maybe a decoupling cap and a rc filter to make the sound a bit nicer than harsh square waves.

author: newbrain
author_rank: Super Contributor
timestamp: March 14, 2024, 08:37:03 am
content: Quote from: andy3055 on March 12, 2024, 06:34:25 pmFor you it's like a precious gem.No spoiler tag here, so...(Pun based on the name Hōseki, ほうせき, meaning precious stone, gem, jewel)

author: EPAIII
author_rank: Super Contributor
timestamp: March 14, 2024, 10:49:16 am
content: I have a kitchen timer (minutes and seconds) that makes that exact sound. I use it to wake me after sleeping for an hour or so because I get uncomfortable after that when in bed. I always thought it was some kind of digital square wave thing which would be an efficient use of the coin cell battery that it uses. Even though I use it every day, that battery lasts for half a year or more.

author: wraper
author_rank: Unknown
timestamp: March 14, 2024, 12:27:47 pm
content: Quote from: pcprogrammer on March 14, 2024, 07:33:20 amI think it will actually sound worse if harmonics are removed.

author: soldar
author_rank: Super Contributor
timestamp: March 14, 2024, 01:11:46 pm
content: For illustration.